With the assistance of peptides, a stable and highly efficient approach for the quick loading of thiol–DNA onto AuNPs is proposed with a high DNA utilization, which is generally applicable to specific DNA detection and diverse AuNP sizes. The maximum efficiency of hybridization reached 93% while the reaction time was shortened to 30 min.

Field and pretreatment-free detection of heavy-metal ions in organic polluted water is important but still challenging in current water pollution emergency response systems. Here we report a polyadenine–DNA-mediated approach for a rationally designed alkyne-coded surface-enhanced Raman scattering (SERS) test kit, enabling rapid and simultaneous detection of Hg2+ and Ag+ by a portable spectrometer, impervious to organic interferences. Because of the formation of thymine (T)–Hg2+–T and cytosine (C)–Ag+–C, highly recognizable SERS signals are rapidly detected when two different alkyne-labeled gold nanoparticles (AuNPs) are induced to undergo controllable bridging upon the addition of low-volume targets. For multiplex detection through a portable spectrometer, the limits of detection reach 0.77 and 0.86 nM for Hg2+ and Ag+, respectively. Of particular significance, the proposed C≡C-containing Raman reporters provide an extremely effective solution for multiplex sensing in a spectral silent region, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm–1) are inevitable under complex ambient conditions.Keywords: alkyne; metal ions; organic-rich water sample; probe; SERS; test kit

The alkyne tags possess unique interference-free Raman emissions but are still hindered for further application in the field of biochemical labels due to its extremely weak spontaneous Raman scattering. With the aid of computational chemistry, herein, an alkyne-modulated surface-enhanced Raman scattering (SERS) palette is constructed based on rationally designed 4-ethynylbenzenethiol derivatives for spectroscopic signature, Au@Ag core for optical enhancement and an encapsulating polyallylamine shell for protection and conjugation. Even for the pigment rich plant cell (e.g., pollen), the alkyne-coded SERS tag can be highly discerned on two-dimension distribution impervious to strong organic interferences originating from resonance-enhanced Raman scattering or autofluorescence. In addition, the alkynyl-containing Raman reporters contribute especially narrow emission, band shift-tunable (2100–2300 cm–1) and tremendously enhanced Raman signals when the alkynyl group locates at para position of mercaptobenzene ring. Depending on only single Raman band, the suggested alkyne-modulated SERS-palette potentially provides a more effective solution for multiplex cellular imaging with vibrant colors, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm–1) are inevitable under complex ambient conditions.

Nitrites (NO2− ions) in food and drink play an important role in human health but require complicated operations before detection. Herein, we present a rationally designed SERS-enabled micro-chamber that comprised a drawn glass capillary with a tiny orifice (∼50 μm) at the distal tip, wherein the gold nanoparticles (Au NPs) are compactly coated on the inner wall surface. In this chamber, nitrites specifically trigger a pH and laser irradiance-dependent diazotization starting from p-aminothiophenol (PATP) absorbed onto the surface of Au NPs to form p,p′-dimercaptoazobenzene (DMAB) molecules, in which the presence of NO2− ions above 30.7 μM (1.38 ppm) in the siphoned liquid sample can be identified relying on SERS peak (1141 cm−1) intensity of the emerging azo moiety. Except for pH conditions, laser irradiance is more important but easily neglected in previous studies, which is capable of preventing generation of errors when the detection sensitivity was pursued through increasing the laser power. In this case, several real samples (rather than simple water samples), including honey, pickled vegetable and fermented bean curd, had been successfully detected accurately through such a convenient sampling micro-chamber. The SERS-enabled device could potentially be facilely incorporated with portable Raman instruments for a special application of food inspection in rapid and field analysis of NO2− ions.

Methane-oxidizing bacteria (MOB) are a unique group of gram-negative bacteria that are proved to be biological indicator for gas prospecting since they utilize methane as a sole source of carbon and energy. Herein the feasibility of a novel and efficient gas prospecting method using Raman spectroscopy is studied. Confocal Raman spectroscopy is utilized to establish a Raman database of 11 species of methanotrophs and other closely related bacteria with similar morphology that generally coexist in the upper soil of natural gas. After strict and consistent spectral preprocessing, Raman spectra from the whole cell area are analyzed using the combination of principal component analysis (PCA) and Mahalanobis distance (MD) that allow unambiguous classification of the different cell types with an accuracy of 95.91%. The discrimination model based on multivariate analysis is further evaluated by classifying Raman spectra from independently cultivated bacteria, and achieves an overall accuracy of 94.04% on species level. Our approach using Raman spectroscopy in combination with statistical analysis of various gas reservoirs related bacteria provides rapid distinction that can potentially play a vital role in gas exploration.

We herein present a simple and surfactant-free synthetic strategy for the preparation of core–shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles (FBNPs) via a combination of galvanic replacement and reagent reduction, in which a chitosan (CS)-mediated epitaxial growth of Pt multi-branches occurs on cresyl violet labeled Au core–Ag shell nanoparticles (NPs) at room temperature. The as-prepared novel nanostructures exhibit an enzyme mimetic activity due to the formation of a Fructus Broussonetia-shaped Pt shell, the absence of surfactants and the positively charged CS molecules intertwined within the outermost Pt NPs. Relying on the high sensitivity of resonance-enhanced Raman scattering and the highly efficient intrinsic peroxidase-like activity of FBNPs, H2O2 was detected with a wide detection window from 10 pM to 100 μM when utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate. Based on the H2O2–TMB catalytic oxidation system a simple, sensitive, selective and universal platform has been extended for the detection of all peroxidase-related analytes. For example, glucose at a concentration range of 1 nM to 200 μM was detected in the presence of glucose oxidase with a limit of detection of 1 nM.

This review (with 139 refs.) gives a fundamental introduction into the sensors and logic gates based on G-quadruplexes (G4s). G4 characterizes vibrant binding activities and topology diversity, which contribute to the multiple signal output modes (including labeled moieties based on distance changes, label-free outputs by employing fluorescent ligands, G4/hemin DNAzyme with catalyzing activity and colorimetric readout using gold nanoparticles) and versatile design strategies (including target-induced G4 formation/disruption, liberation of blocked G4, split G4 probes, polymerase-assisted amplification and G4/hemin enrichment on sensor surface) of G4s-based methods. Following two important trends in logic gates (application of intelligent detection schemes and logic circuit constructions), specific sections review logic sensors and logic circuits based on G4s with several representative examples. We close this review with conclusions and give a perspective that employment of DNA technologies (such as aptamers, DNA junctions/origami, toehold-mediated strand displacement, enzyme-assisted amplification, metal ion-dependent DNAzymes) and various nanomaterials in G4s-based methods results in quite a large potential in terms of logic detection and construction of logic circuits.

Novel three-dimensional (3D) nano-assemblies of noble metal nanoparticle (NP)–infinite coordination polymers (ICPs) are conveniently fabricated through the infiltration of HAuCl4 into hollow Au@Ag@ICPs core–shell nanostructures and its replacement reaction with Au@Ag NPs. The present 3D nano-assemblies exhibit highly efficient and specific intrinsic oxidase-like activity even without adding any cosubstrate.

We report the first microsampling device for reliably quantitative, label-free and separation-free detection of multicomponents of surface organic residues (SORs) by means of a quality controllable surface-enhanced Raman scattering (SERS)-enabled micropipette. The micropipette is comprised of a drawn glass capillary with a tiny orifice (∼50 μm) at the distal tip, where the specially designed nanorattles (NRs) are compactly coated on the inner wall surface. SERS signals of 4-mercapto benzoic acid (MBA) anchored inside the internal gap of NRs could be used to evaluate and control the quality of micropipettes and, therefore, allow us to overcome the limitations of a reliably quantitative SERS assay using traditional substrates without an internal standard. By dropping a trace extraction agent on targeting SORs located on a narrow surface, the capillary and SERS functionalities of these micropipettes allow on-site microsampling via capillary action and subsequent multiplex distinction/detection due to their molecularly narrow Raman peaks. For example, 8 nM thiram (TMTD), 8 nM malachite green (MG), and 1.5 μM (400 ppb) methyl parathion (MPT) on pepper and cucumber peels have been simultaneously detected in a wide detection range. The portable SERS-enabled device could potentially be facilely incorporated with liquid–liquid or solid phase micro-extracting devices for a broader range of applications in rapid and field analysis of food/public/environment security related SORs.

By employing two-dimensional and water-soluble graphene oxide (GO), a turn-on sensor was developed for the label-free detection of Zn2+ based on Zn2+-induced G-quadruplex (G4) formation. Indicated using the G4-binding ligand thiazole orange (TO), the enhanced fluorescent signal could be generated only when the guanine-rich DNA was excluded from the surface of GO due to the formation of a G4 induced by Zn2+. The results have shown that the method can be utilized for the detection of Zn2+ in a linear range from 0–30 μM with a detection limit of 0.71 μM. The real sample testing conducted in serum samples demonstrated its practical potential in biological analysis.

•This label-free assay avoids modification, offers cost efficiency.•No separation procedure is needed for the sensing.•The sensor responses rapidly, and takes 20 min to complete the Cys-sensing.•This “turn-on” sensor shows high sensitivity and selectivity.A Hg2+-mediated fluorescence turn-on sensor for cysteine (Cys) detection was developed using the nucleic acid minor groove binding dye DAPI. In this work, two fully complementary DNA sequences, a T-rich single-stranded molecule (ssDNA) and an A-rich single-stranded molecule, were employed to constitute consecutive “AT/TA” base pairs, which could strongly enhance the fluorescence of DAPI. In the absence of cysteine, Hg2+ reacted with T-rich single-stranded DNA and “T–Hg2+–T” base pairs formed, this seriously disrupted consecutive AT base pairs. As a result, the fluorescence of DAPI was not increased efficiently. However, considering that cysteine binds strongly to Hg2+, the structure of the “T–Hg2+–T” complexes was destroyed in the presence of cysteine, resulting in the re-formation of consecutive AT base pairs and increased DAPI fluorescence. Obviously, the amount of cysteine could be easily measured based on the enhancement of DAPI fluorescence, and it took only 20 min to complete the whole cysteine-sensing process. Therefore, a label-free fluorescent “turn-on” sensor for the rapid detection of cysteine was designed, and the detection limit of this sensor was as low as 2.4 nM, which was much lower than those of the most of the previously reported cysteine sensors.In the absence of Cys, Hg2+ bound to thymine and formed “T–Hg2+–T”, so that AT base pairs between S1 and S2 were seriously disrupted and the fluorescence of DAPI was effectively suppressed. However, the presence of Cys completely changed the situation: Cys removed Hg2+ far away from the structure of “T–Hg2+–T” with its active sulfhydryl group, then AT base pairs appeared and the fluorescence of DAPI was successfully enhanced. Therefore, the amount of Cys could be easily measured according to the fluorescence enhancement of DAPI.

•“Turn-on” SERS-based enzymatic assay is newly proposed.•The method works on catalytic property of trypsin to cleave peptides.•Ultrasensitive detection of target was achieved together with potential as a SERS-based label-free approach.•We proved the universality of the method as a general approach for proteases.We describe herein a novel' “turn-on” SERS-based strategy for protease detection based on surface enhanced Raman scattering (SERS) and the mediation of spacing between 4-mercaptobenzoic acid (4-MBA) labeled gold nanoparticles (AuNPs) through enzyme assays. The method employed non-cross-linking aggregation of 4-MBA-modified AuNPs by peptides after treatment with target protease. Thus, SERS signals of 4-MBA are sharply increased because of the decreased electrostatic stability of AuNPs that initiated gold nanoaggregates incorporating Raman reporter molecules due to the formation of “Hot Spots”. Through this strategy, a novel and facile “turn-on” SERS biosensor for trypsin and thrombin based on enzymatic cleavage activity is established with sensitivity, selectivity and simplicity as AuNPs and peptides are easily accessible. Compared with other methods, this newly proposed method has improved sensitivity. The limit of detection was 85 fM (at the ratio of signal to noise, S/N=3:1) for trypsin. Controlled experiments showed that the method exhibited good selectivity over other proteases. We also proved that this principle could be easily adapted to detection of other proteases such as thrombin. The method demonstrated the capability for application in complex matrix samples. The results also presented the potential and superiority of SERS biosensor as a general approach for proteases based on enzyme activity.

A simple, toehold-mediated two-way input DNA machine has been developed. Utilizing symmetric and asymmetric protector sequences, INH, XOR logic gates and a half-subtractor are designed based on this two-way structure.

Noble metal nanoparticles (NPs) are spontaneously enfolded by aqueous coordination networks generated by reacting 2,5-dimercapto-1,3,4-thiadiazole (DMcT) with silver nanostructures in zero-oxidation state, and finally form novel hollow Au@Ag@infinite coordination polymers core–shell nanostructures (Au@Ag@void@ICPs). In this synthesis, DMcT molecules not only act as the bridging ligands but also directly oxidize Ag0 to Ag+ ions for the formation of amorphous DMcT–Ag ICPs. And, the sizes of the shell and void of Au@Ag@void@ICPs can be facilely tuned by modulating the amount of DMcT and the size ratio of Au@Ag NPs, respectively. Due to the high structural tailorability of DMcT–Ag ICPs, multi-encapsulation of Au@Ag NPs with either small organic molecules or biological macromolecules (e.g., enzymes) can be achieved to fabricate multi-functional core–shell nanostructures. A case in point is that a highly sensitive biosensor of H2O2 with a wider detection window has been constructed based on the prepared metal NPs–ICPs–enzyme composites and resonance Raman scattering. This study provides not only a new template for tailoring hollow core–shell nanomaterials but also a versatile platform for chemical (bio) sensing.

•The aggregation and sedimentation of nanoparticles were prevented.•Two kinds of DNA can be determinated in one tube simultaneously by naked-eye.•A novel chemometrics-based protocol for quantitative analysis was developed.•This sensor can quantify two kinds of DNA simultaneously with a pM level sensitivity.Herein, a one-tube colorimetric platform has been developed for the simultaneous determination of two analytes (DNA as model object) in one tube with picomolar sensitivity. SPR-active nanoparticles are used to encode reporter probes sensitive to oligonucleotides associated with hepatitis A virus Vall7 polyprotein gene (HVA) and hepatitis B virus surface-antigen gene (HVB) respectively and magnetic beads (MBs) serve as the removal tool. In this mixed nanoparticles based biosensor, the addition of target analytes could change the concentration of each nanoparticle, leading to different colors of the supernatant. The influence of spectral overlap has been eliminated by a non-negative matrix factorization (NMF). With the assistance of NMF, the limit of detection (LOD) can be determinated as pM level without amplification. On the whole, this nanosensor boasts the advantages of high sensitivity and low sample consumption. Simultaneous colorimetric detection and quantification of two molecules in one tube are demonstrated.A one-tube colorimetric platform has been developed for the simultaneous determination of two analytes in one tube with picomolar sensitivity. The influence of spectral overlap has been eliminated by the non-negative matrix factorization (NMF). The results of the analysis show the LOD is as low as pM level.

We describe a highly sensitive and spectrally stable surface-enhanced Raman scattering (SERS) tag for live cell imaging based on carbon-encapsulated gold nano-aggregates (CEGNAs). Our findings reveal that controlling the synthesis of the gold nano-aggregate core can be achieved under the mediation of cetyltrimethylammonium bromide (CTAB) through electrostatic forces and hydrophobic interactions, and as the number of particles in the aggregates increase, the relative SERS activity also increases hugely.

In this essay, three novel nonlinear optical (NLO) azo-materials containing indole and sulfonyl based chromophores were studied in-depth by using Fourier transform (FT) IR, FT-Raman spectra and density functional theory (DFT). The scaled theoretical results were shown to be in good agreement with the experimental data. In addition, the computed 1H nuclear magnetic resonance (NMR) and UV–vis absorption wavelengths were also discussed compared with experimental data. The large β values calculated by the DFT methods showed that the studied molecules were good NLO materials, and the molecule which owned a larger substituent group on the indole chromophore moieties had a larger value. Furthermore, simultaneous infrared and Raman activity suggested that intramolecular charges might transfer through the conjugated framework from the electronic donor group to electronic acceptor group. The HOMO–LUMO gap analysis and molecular electrostatic potential (MEP) maps also supported this viewpoint.Graphical abstractThe simultaneous strong Raman and infrared activity of some vibrations suggests that the charge transfer through the conjugated framework from the donor to acceptor group and the HOMO–LUMO analysis gives the supported information.Highlights► FT-IR, FT-Raman, 1H NMR and UV spectra of three novel NLO materials. ► The relationship between structure, β value and NLO properties is discussed. ► The donor and acceptor groups are discussed by vibrational analysis.

Herein we describe a novel “turn-off” biosensing strategy for thrombin detection based on Surface Enhanced Raman scattering (SERS) and the mediation of spacing between 4-mercaptobenzoic acid (4-MBA) labeled gold nanoparticles (AuNPs). The multiple arginine peptides that initiated gold nano-aggregates incorporating Raman reporter molecules due to the formation of “Hot Spots”, are induced to disband by the addition of thrombin in which the peptides are catalytically cleaved into fragments and thus SERS signals of 4-MBA are sharply declined because of the weakened ability of fragments to induce aggregation. Through this strategy, a novel “turn-off” SERS biosensor for thrombin based on enzymatic amplification is established with sensitivity, selectivity and simplicity as AuNPs and peptides are easily accessible. Compared with non-enzymatic amplification based methods, this newly proposed method has improved sensitivity. The limit of detection was 160 fM (at the ratio of signal to noise, S/N=3:1). Further, controlled experiments showed that the method exhibited good selectivity over other proteases. The method demonstrated the capability and the potential for application in complex matrix and future biomarker development. The results also presented the potential and superiority of SERS biosensor based on signal amplification.Highlights► “Turn-off” SERS-based enzymatic assay is newly proposed. ► The method works on catalytic property of thrombin to cleave multi-arginine peptides. ► Ultrasensitive detection of target was achieved together with potential of use in complex matrix.

•This novel strategy is based on ligand-responsive G-quadruplex formation.•The assay is label free for rapid DNA detection.•This probe is simple and cost-efficiency in design and operation.A facile and label-free assay with label-free molecular beacons (MBs) and fluorescent dye N-methyl mesoporphyrin IX (NMM) was developed for the detection of specific single-stranded DNA sequences. It was demonstrated by a reverse transcription oligonucleotide sequence (target DNA, 20 bases) of RNA fragment of human immunodeficiency virus (HIV) as model systems. In the absence of target DNA, the MBs were in the stem-closed form, the G-quadruplex structure could not form and the fluorescence signal of NMM was very low. In the presence of target DNA the MBs turned “Off” to “On”, thus promoting the formation of G-quadruplex which could greatly enhance the fluorescence of NMM. This biosensor was simple in design, fast in operation, and more convenient and promising than other methods. It took less than 30 min to finish and its detection limit was 1.4 nM. No sophisticated experimental techniques or chemical modification for DNA sequences were required. This new approach could be widely applied to sensitive and selective nucleic acids detection.

A selective and sensitive fluorescence biosensor for Ag+ ions and cysteine (Cys) was developed based on the chelation actions between Ag+ ions and guanine bases of G-rich fluorogenic oligonucleotide (FAM-ssDNA) and the different electrostatic affinity between FAM-ssDNA and graphene oxide (GO). FAM-ssDNA adsorbed onto the surface of GO through π–π stacking interaction between the ring structure in the nucleobases and the hexagonal cells of GO, and the fluorescence of the dye was quenched. In the presence of Ag+ ions, the random coil structure changed into a G-Ag+ architecture. As a result, the binding released FAM-ssDNA signal probe from the surface of GO, which disrupted the energy transfer from FAM-ssDNA to GO, recovering the fluorescence emission of FAM-ssDNA. On the other hand, because Cys was a strong Ag+ ions binder, it could deactivate the sensor fluorescence by rewrapping FAM-ssDNA around GO. In this way, these changes in fluorescence intensity allowed the selective detection of Ag+ ions and Cys.Highlights► The positive effect of Ag+ on fluorescence of FAM-ssDNA was first proposed. ► A turn-on fluorometric assay for Ag+ and turn-off assay for cysteine were designed. ► The more G units of ssDNA, the stronger enhancement of fluorescence.

The manuscript has investigated the application of near-infrared (NIR) spectroscopy for differentiation gastric cancer. The 90 spectra from cancerous and normal tissues were collected from a total of 30 surgical specimens using Fourier transform near-infrared spectroscopy (FT-NIR) equipped with a fiber-optic probe. Major spectral differences were observed in the CH-stretching second overtone (9000–7000 cm−1), CH-stretching first overtone (6000–5200 cm−1), and CH-stretching combination (4500–4000 cm−1) regions. By use of unsupervised pattern recognition, such as principal component analysis (PCA) and cluster analysis (CA), all spectra were classified into cancerous and normal tissue groups with accuracy up to 81.1%. The sensitivity and specificity was 100% and 68.2%, respectively. These present results indicate that CH-stretching first, combination band and second overtone regions can serve as diagnostic markers for gastric cancer.Graphical abstractHighlights► Major spectral differences were observed in three regions. ► Unsupervised pattern recognition techniques (PCA and CA) were used. ► The sensitivity, specificity and accuracy were 100%, 68.2% and 81.1%, respectively.

In the present study, silica nanoparticles with resonance Raman scattering (RRS) properties were utilized to construct a novel resonance Raman scattering tag for in vivo cellular imaging. β-Carotene, a native pigment insoluble in water, was for the first time encapsulated in silica nanoparticles through a simple one-step procedure in which β-carotene was enriched in the micelle of cetyltrimethylammonium bromide (CTAB) and simultaneously enclosed during the hydrolysis of tetraethylorthosilicate (TEOS). The particles were characterized by using X-ray diffraction, transmission electron microscopy (TEM), and Raman spectroscopy. Results showed that the size distribution of β-carotene doped silica nanoparticles (CSNPs), which were highly dispersible in aqueous solution, was fairly uniform in the range of 60 to 200 nm. Due to the advantages of highly stable and repeatable RRS signals of doped β-carotene, a simple cellular imaging approach based on this novel Raman tag has been preliminarily achieved. This paper demonstrated that resonance Raman scattering tags are important candidates for biological applications considering their high biocompatibility and spectral stability.

A simple, rapid colorimetry for DNA detection based on non-aggregated gold nanoparticles and magnetic beads has been developed with high selectivity and sensitivity.

A recent study reported by Higuchi's group has shown that Pt–DNA complexes possess peroxidase enzymatic activity similar to natural peroxidases. In this study, we prepared Pt–DNA complexes and demonstrated their use in catalyzing the oxidation of a peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to the oxidized product which provided a colorimetric detection of H2O2. As low as 3.92 × 10−4 mol L−1 H2O2 could be detected with a linear range from 9.79 × 10−4 to 1.76 × 10−2 mol L−1via our method. Furthermore, PVDF membranes were employed to increase sensitivity and decrease the detection limit of H2O2, enabling a two-fold improvement in the detection sensitivity as compared with the above counterparts. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepared Pt–DNA complexes. We realized the test of glucose as low as 10−7 mol L−1 by the color change, which was comparable to or even better than the existing methods, and identified the concentration of glucose in Sprite with the naked eye without referring to any sophisticated apparatus. The detection platforms for H2O2 and glucose developed in the present work showed great potential for applications in the future.

A bi-detection system integrated by laser-induced fluorescence (LIF) and retro-reflected beam interference (RBI) based refractive index was established and applied to simultaneously determine erythrosine and sucrose in candy floss. The system realized separation-free analysis of candy floss without prior concentration steps.

Novel functional oligonucleotides, especially DNAzymes with RNA-cleavage activity, evoke current research interest increasingly due to their potential applications in therapeutics and sensors. One of the most attention-attracting is the lead-specific DNAzyme, which is composed of an enzyme strand 17E and a substrate strand 17S, addition of Pb2+ enables the DNAzyme to cleave its substrate. In this study, we took advantage of the unique optical properties of a water-soluble cationic polythiophene (PT) and designed a fluorometric sensing assay for the detection of Pb2+. A simple “mix-and-detect” approach enabled the detection of Pb2+ within 20 minutes due to the distinguishable optical properties of PT–dsDNA and PT–ssDNA. As low as 10 nM Pb2+ could be detected with a detection range from 10 nM to 100 μM via this method. Furthermore, this method was highly selective and only minimally perturbed by nonspecific metal ions. Since common steps such as modification and separation could be successfully avoided, this simple, sensitive, specific, and cost-effective approach showed great potential applications in environmental monitoring, waste management and clinical toxicology.

In this work, a new platform for effective sensing cysteine (Cys) was developed based on fluorescence resonance energy transfer (FRET) between FAM-tagged single-stranded DNA (FAM-ssDNA) and graphene oxide (GO). Due to the noncovalent assembly between FAM-ssDNA and GO, fluorescence quenching of the FAM took place because of FRET. This method relied on the competitive ligation of Ag+ by Cys and “cytosine–cytosine” (C–C) mismatches in a FAM-labeled DNA strand of the self-hybridizing strand. At first, enough amount of Ag+ was introduced to bind “C–C” mismatches and form double-stranded DNA (dsDNA), which had weak affinity to GO and kept FAM away from GO surface. However, the presence of Cys removed Ag+ away from “cytosine–Ag+–cytosine” (C–Ag+–C) base pairs, leading to the formation of ssDNA again and FRET, and then fluorescence of the FAM-ssDNA was efficiently quenched. The fluorescence intensity decrease was found to be proportional to the increase of concentration of Cys in both aqueous buffer (2–200 nM) and human serum (5–200 nM), and the sensitivity of the proposed method towards Cys was much higher than that of other reported assays for Cys.Highlights► A new platform for fluorescent detecting cysteine was designed. ► FRET between FAM-ssDNA and GO was researched to construct the method. ► Detection of cysteine has been effectively realized in buffer and serum.

A simultaneous laser-induced fluorescence (LIF), coaxial thermal lens spectroscopy (TLS) and retro-reflected beam interference (RBI) detection for capillary electrophoresis (CE), has been described. In its optical scheme, a diode-pump solid-state (DPSS) laser was employed as the pump laser in both LIF detection and coaxial TLS detection, and a He–Ne laser was utilized as the probe laser in coaxial TLS detection and RBI detection. In addition, RBI signals with and without thermal lens had been theoretically compared to ensure the reliability of the RBI signal. Moreover, the focus length of the key lens has been optimized to improve the performance of the proposed detection. The last but not least, several determinations were taken to evaluate its limit of detection, linear range as well as relative standard deviation, all of which indicate no worse results compared with former reports. LIF and coaxial TLS detection owned high sensitivity, and RBI detection indicated versatile property, based on which the reported detection achieved a sensitive and universal detection for CE.Highlights► We realize concurrent fluorescence, thermal lens and interference detection for CE. ► Beam interference signals were theoretically calculated to ensure its reliability. ► The lens focus in the detection scheme has been optimized. ► The reported strategy achieved a sensitive and universal detection for CE.

Laser-based refractive index detection, based upon refractive index changes in micro-channels, is a kind of laser-based optical determination for solutions. As it is capable of label-free determination, it has been regarded as a considerable growth prospect. The key aspect in related researches lay in the development of novel detection configurations, which would possibly result in better sensitivity. Over the past decade, micro-channel laser-based refractive index detection has been significantly improved, resulting in traversed, hologram-based, back-scattered, retro-reflected interference, optical ring resonant, etc., detection configurations. Moreover, laser-based refractive index detection has been combined with other laser-based detection strategies, in order to pursue a universal and sensitive detection. And last but not least, some utilizations of laser-based refractive index detection have been reported, while both advantages and drawbacks exist. In this paper, laser-based refractive index detection for micro-channels will be reviewed in proceeding sequence.

A novel method for simultaneous determination of sucrose and sunset yellow in retail soft drink without separation by combination of retro-reflected beam interference-based refractive index (RBI) and thermal lens (TL) detections was developed. The method proposed here successfully realized individual measurements of sucrose and sunset yellow in one single sample, while their concentrations were thousands of times different in the sample. Under optimized conditions, a separation-free process was carried out so that sucrose and sunset yellow were quantified at the same time. Limits of detection (LODs) of sucrose and sunset yellow were 0. 21 mg ml−1 and 0.23 μg ml−1 and the relative standard deviation (RSDs) were 3.9% and 3.07%. The developed method was successfully applied for the simultaneous analysis of sucrose and sunset yellow in retail soft drink. The soft drink containing 123.6 ± 2.6 mg ml−1 sucrose and 46.6 ± 1.8 μg ml−1 sunset yellow have been simultaneously measured without any separation procedure.

With the technical progress in lasers, charge coupled device detectors, and fiber-optic probes, Raman spectroscopy (RS) is enjoying a strong resurgence in the field of biomedical science, especially in disease diagnosis. During this time we have witnessed more and more in vitro and in vivo applications of RS, and increasingly frequent reports of its utility. RS enables the extraction of biochemical signatures from biological tissues, and in conjunction with different statistic algorithms, the spectral data with various pathologic attributions can be differentiated and classified depending on their spectral differences, e.g., peak area, peak height or peak shape. This makes RS a potential clinical analytical technique for rapid and non-destructive diagnosis of human diseases. This paper is a review of the biomedical applications of Raman spectroscopic techniques in diagnostics. First, a brief illumination of RS instrumentation and algorithms for data analysis is introduced. Then wide utilization of RS in disease diagnosis is reviewed categorized by different tissues and organs, including brain, eye, body surface organs (breast, skin), abdominal organs (stomach, esophagus, colon, liver), thoracic organs (arteries, lung), reproductive and urinary organs (prostate, cervix, bladder) and hard tissue (bone, teeth). Some other work from our group are also introduced.

Three biosurfactant-producing indigenous microorganisms (XDS1, XDS2, XDS3) were isolated from a petroleum reservoir in the Daqing Oilfield (China) after polymer flooding. Their metabolic, biochemical, and oil-degradation characteristics, as well as their oil displacement in the core were studied. These indigenous microorganisms were identified as short rod bacillus bacteria with white color, round shape, a protruding structure, and a rough surface. Strains have peritrichous flagella, are able to produce endospores, are sporangia, and are clearly swollen and terminal. Bacterial cultures show that the oil-spreading values of the fermentation fluid containing all three strains are more than 4.5 cm (diameter) with an approximate 25 mN/m surface tension. The hydrocarbon degradation rates of each of the three strains exceeded 50%, with the highest achieving 84%. Several oil recovery agents were produced following degradation. At the same time, the heavy components of crude oil were degraded into light components, and their flow characteristics were also improved. The surface tension and viscosity of the crude oil decreased after being treated by the three strains of microorganisms. The core-flooding tests showed that the incremental oil recoveries were 4.89–6.96%. Thus, XDS123 treatment may represent a viable method for microbial-enhanced oil recovery.

We have synthesized a stable, sensitive and specific surface-enhanced Raman tag, and demonstrated its application in human α-thrombin detection. The tag consists of aptamer-modified core–shell nanoparticles with hydrophobic Au@Ag as core and silica as shell encapsulating Raman active molecules. By taking advantage of the Raman signal enhancement effect by metallic nanostructures, high stability and robustness of glass-coated core–shell nanostructures and the recognition capabilities of aptamers, we designed a sandwich detection for protein identification with high selectivity and sensitivity. In this way, we realized the ultrasensitive detection of α-thrombin. GDNs (glass-coated, dye-tagged nanoparticles), which were conjugated with oligonucleotides or antibodies, were extremely soluble in water, and had mechanical and chemical stability, easily controllable-size distribution and friendly biocompatibility. Specifically, the glass coating renders the particles amenable to use in many solvents without altering the Raman spectral response and makes agglomeration a nonfactor. All these merits open the door of the real applications in diagnostics or medical investigations in complex biofluids, such as human plasma and serum. Using the aptamer-modified GDNs as Raman tags, we successfully performed the detection of α-thrombin in human plasma. Furthermore, the overall method have been proved effective and selective, and may be implemented for multiplex target analysis simultaneously.

In this study, β-carotene, a resonance Raman active substance, was introduced into the large pore channel of rod-like SBA-15 for the first time. This novel resonance Raman active material has been characterized by small angle X-ray scattering (SAXS) and Brunauer–Emmett–Teller (BET) surface area analysis. The adsorption process did not show any influence on the microstructure of SBA-15 as well as its physicochemical characters. Excited by 514.5 nm laser, the resonance Raman signals of the products were demonstrated as well-defined Raman peaks at 1009, 1158 and 1514 cm−1, which should be assigned to the methyl rock (C–CH3), carbon single-bond stretch (C–C) and carbon double-bond stretch (CC) normal modes, respectively. In addition, the internal standard method was utilized by resonance Raman spectroscopy to determine the adsorption capacity of mesoporous silicas for β-carotene using the results of UV–vis spectroscopy as a reference.

A longitudinal study was established to investigate bone compositional information in spinal cord injury (SCI) rat model.Raman spectroscopy was applied to detect the distal femur and humeri of SCI, sham-operated (SO), and age-matched control (CON) male Sprague-Dawley (SD) rats at first, second, third, and fifth weeks after surgery. One-way ANOVA and Tukey’s HSD post hoc multiple comparison tests were used to analyze the longitudinal data of mineral to matrix ratio and carbonate substitution.Relative mineral decrease was found in SCI group by more than 20% in femur and approximately 12% in humeri compared with CON group. No significant changes in carbonate substitution were observed.Severe bone loss in the early stage of SCI was confirmed by a continuous decrease of the mineral to collagen matrix ratio. The decrease in the humeri suggested hormone level variations might participate in the etiology of SCI-induced osteoporosis.

A simple method of fabricating shape-tunable Au nanopeanuts from Au–Ag core–shell nanoparticles based on both galvanic replacement and reagent reduction is described.

A novel and highly selective optical sensor with molecularly imprinted polymer (MIP) film was fabricated and investigated. The optical sensor head employing a medium finesse molecularly imprinted polymer film has been fabricated and characterised. A blank polymer and formaldehyde imprinted polymer were using methacrylic acid as the functional monomer and the ethylene glycol dimethacrylate as a crosslinker. The transduction mechanism is discussed based on the changes of optical intensity of molecularly imprinted polymer film acting as an optical reflected sensor. Template molecules, which diffused into MIP, could cause film density, and refractive index change, and then induce measurable optical reflective intensity shifts. Based on the reflective intensity shifts, an optical reflection detection of formaldehyde was achieved by illuminating MIP with a laser beam. For the same MIP, the reflective intensity shift was proportional to the amount of template molecule. This optical sensor, based on an artificial recognition system, demonstrates long-time stability and resistance to harsh chemical environments. As the research moves forward gradually, we establish the possibilities of quantitative analysis primly, setting the groundwork to the synthesis of the molecular imprinted optical fiber sensor. The techniques show good reproducibility and sensitivity and will be of significant interest to the MIPcommunity.

We present a novel nuclear targeting nanoprobe based on peptide functionalized gold nanoparticles and its surface-enhanced Raman scattering (SERS) in living cells. For the first time, we probe an original SERS signal from the living cell nucleus by using high-selectivity functionalized gold nanoparticles. The gold nanoparticles conjugated with SV-40 large T nuclear localization signal (NLS) peptide successfully enter the cell nucleus after the incubation with Hela cells and deliver the spatially localized chemical information of the nucleus, as well as the signature of chemicals that intruded subsequently. This new targeted nanoprobe is a nontoxic, biocompatible method for biological research, provided with multiple functions comprising subcellular targeting, intracellular imaging, and real-time SERS detection.

We report a combined experimental and computational study of the large self-assembly complex (CoL)2 [L= bis(2,4,8,10-tetramethyl-9-methoxycarbonylethyldipyrrin-3-yl)methane] containing 172 atoms. An extensive density functional theory (DFT) and time-dependent DFT study of this complex in gas phase and in CH2Cl2 solution was performed, investigating the effect of substitutions of methyl and methyl propionate on the electronic structure and optical properties of this complex. The calculated IR and Raman spectra are in excellent agreement with the experiment, thus allowing a detailed assignment of the vibrational absorption bands. Comparing the vibrational spectrum of (CoL)2 with that of (ZnL′)2 [L′ = bis(2,4-dimethyldipyrrin-3-yl)methane], the substitution of methyl on the Cβ atom results in sizable shifts on the same modes; particularly in the case of mode υ(Cβ−Cβ), the shift is more than 20 cm−1. The lowest 70 singlet−singlet spin-allowed excited states were taken into account for the calculation by TDDFT in gas phase and PCM-TDDFT in CH2Cl2 solution. Theoretical calculations provide a good description on positions of the two band maximums in observed spectrum but predict a contrary relatively intensity for these two bands. In the UV−vis absorption spectrum of (CoL)2 complex, the band maximum at 525.5 nm is mainly attributed to the π→π* transition. The band maximum at 488.1 nm is originated from metal−ligand charge-transfer (MLCT) transition mixed with interligand π→π* transition.

A novel H2O2 biosensor has been fabricated based on the direct electrochemistry and electrocatalysis of myoglobin (Mb) immobilized on silver nanoparticles doped carbon nanotubes film with hybrid sol–gel techniques. A pair of redox peaks with peak separation of 160 mV and formal potential of −0.295 V was observed at this composite film, corresponding to the direct electrochemistry of Mb. The heterogeneous rate constant was estimated to be 0.41 s−1. Under optimum conditions, the amperometric determination of H2O2 was performed with a linear range of 2.0 × 10−6–1.2 × 10−3 mol L−1 and a detection limit of 3.6 × 10−7 mol/L (S/N = 3). The Michealis–Menten constant was also estimated to be 1.62 mmol L−1. The proposed biosensor showed favorable reproducibility, stability, selectivity and accuracy, and has been used to determine H2O2 in real samples with favorable recoveries.

A hydroxyapatite (Hap) monolithic column with micrometer macropores skeleton structure was prepared by sol–gel technique for efficient DNA extraction. The main extraction mechanism of this monolithic column was attributed to the electrostatic interaction between the phosphate groups of DNA and the calcium ions (C site) of Hap. DNA extraction conditions, such as pH, ion concentration, ion type and loading capacity, on the monolithic column were optimized online by capillary electrophoresis with laser-induced fluorescence detection. Under the optimal condition, a 6 cm length monolithic column provided a capacity of 40 ng DNA with an extraction efficiency of 64 ± 6.2% (X ± RSD). As low concentration of salts were used in the extraction procedure, the purified PBE2 plasmid from the Bacillus subtilis crude lysate could be amplified by polymerase chain reaction. This result illustrated that Hap was a potential matrix for DNA purification from complex biological samples which was compatible with the subsequent genetic analysis in miniature format. Since the preparation of this monolithic column was very simple, it was possible to integrate this novel matrix with chip to allow rapid and efficient DNA purification in microscale. This study provided a new attractive solid-phase support for DNA extraction to meet the miniaturized and automated trends of genetic analysis.

A novel optical scheme, which accomplished simultaneous coaxial thermal lens spectroscopy and retro-reflected beam interference detection for capillary electrophoresis, has been described. By a special design, an adjustable pump laser waist relative to the probe laser waist was implemented, while some key elements for both detection modes were optimized. In either detection modes, certain preponderance compared with former reports was indicated. With both coaxial thermal lens spectroscopy and retro-reflected beam interference detection, the reported detection scheme combined high sensitivity and universal property for capillary electrophoresis detection.

Five triphenyl phosphonium salts including N-phenylacetamidyl triphenyl phosphonium chloride (1), N-phenylpropanamidyl triphenyl phosphonium chloride (2), ethyl 2-methylacetatyl triphenyl phosphonium chloride (3), ethyl butyryl triphenyl phosphonium chloride (4) and hexadecyl triphenyl phosphonium bromide (5) were synthesized and then were characterized by FT-Raman spectroscopy. Surface-enhanced Raman spectroscopy (SERS) in conjunction with electronic absorption spectroscopy was employed to study their interaction with DNA. The decreasing of Raman intensity at 1000, 1029, 1103 and 1588 cm−1 from compound 5 indicated that this compound has affinity for DNA. This was probably because compound 5 inserted into DNA and a new conjugated system was formed. The results of electronic absorption spectra were coincident with those of SERS. On the other hand, compound 5 showed a significant higher inhibitory rate on human cervix cancer cells. The targets of the compounds in the anti-cancer process were discussed. The mechanism of the anti-cancer process of compound 5 might be related to its interaction with DNA.

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase (HRP) onto l-glutathione self-assembled monolayers (SAMs). The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of −0.242 V (vs. saturated Ag/AgCl) in pH 7 phosphate buffer solution (PBS), the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s−1. The HRP-SAMs-based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 × 10−6 mol/L to 1.2 × 10−3 mol/L with a detection limit of 4 × 10−7 mol/L. The apparent Michealis–Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.

A novel approach to the study of microwave enhanced alkaline digestion was developed for rapid digestion of silicate samples. By using alkali metal hydroxide solution as microwave digestion solvent, the feasibility and principle of digestion were discussed for the determination of Fe2O3 contents in quartz, kaolin, feldspar and soda-lime-silica glass. The results obtained from four standard samples and six real world samples are in good agreement with the certified values, and are comparable to the predicted results from traditional alkaline digestion method. All the above demonstrates that this new proposed method is precise, accurate and can provide a simple, fast and energy saving procedure for the determination of components in silicate samples.

Self-assembled monolayers (SAMs) have been widely used in studying interfacial phenomena, biological processes, electrochemistry, photoelectrochemistry, photoactivity and molecular interaction. Much research has been carried out in fabricating and removing SAMs on different substrates. In this work, we report for the first time, to our knowledge, that SAMs of thiolates on gold can be removed by immersing SAMs in 0.5 M NaBH4 solution for 10 min. The procedure of removing thiolates was very convenient. Cyclic voltammetry, surface-enhanced Raman spectroscopy, and X-ray photoelectron spectroscopy were used to characterize this process. The results indicated that the SAMs of thiolates on gold can be removed efficiently by NaBH4.

Thirty-two samples from the human gastric mucosa tissue, including 13 normal and 19 malignant tissue samples were measured by confocal Raman microspectroscopy. The low signal-to-background ratio spectra from human gastric mucosa tissues were obtained by this technique without any sample preparation. Raman spectral interferences include a broad featureless sloping background due to fluorescence and noise. They mask most Raman spectral feature and lead to problems with precision and quantitation of the original spectral information. A preprocessed algorithm based on wavelet analysis was used to reduce noise and eliminate background/baseline of Raman spectra. Comparing preprocessed spectra of malignant gastric mucosa tissues with those of counterpart normal ones, there were obvious spectral changes, including intensity increase at ∼1156 cm−1 and intensity decrease at ∼1587 cm−1. The quantitative criterion based upon the intensity ratio of the ∼1156 and ∼1587 cm−1 was extracted for classification of the normal and malignant gastric mucosa tissue samples. This could result in a new diagnostic method, which would assist the early diagnosis of gastric cancer.

A new hybrid algorithm is proposed to eliminate the varying background of spectral signals. The method is based on the use of multi-resolution, which is one of the main advantages provided by wavelet transform. Compared with the analyte signal, the background has a low frequency. The new method firstly split the signals into different frequency components, and then removes the varying low-frequency background. The method is successfully applied to simulated spectral data set and experimental Raman spectral data. The results showed that the wavelet transform technique could handle all kinds of background and low signal-to-background ratio spectra, and required no prior knowledge about the sample composition, no selection of suitable background correction points, and no mathematical assumption of the background distribution. The proposed procedure was illustrated, by processing real spectra, to be an effective and practical tool for background elimination in Raman spectra. In addition, the proposed strategy can be applied to other spectral signals as well.

Confocal Raman microspectroscopy was used to characterize gastric carcinoma cell in both cultured cells and human gastric mucosa tissues. Based on the spectra of single cultured cell, gastric carcinoma cells were screened out in the malignant gastric mucosa successfully and the positive ratio is about 58.06%. The high SNR (signal-to-noise) spectra from human gastric mucosa tissues and cells were obtained by this technique without any sample preparation and the time of detection required less than 3 min. Comparing spectra of malignant gastric mucosa tissues with those of counterpart normal ones, there were obvious spectral changes, including intensity decrease at ∼1587 cm−1 and alteration of peak shape at ∼1660 cm−1 with malignancy. Additionally, spectral features of single cell also differed from those of stomach tissues at ∼1525 and ∼1156 cm−1 where these two bands were assigned to carotenoids. These results demonstrate the possibility of a rapid clinical diagnosis of gastric carcinoma with Raman microspectroscopy in combination with a remote optical probe.

A novel method of curve fitting based on Gaussian function, which is used to resolve the overlapped peaks, is presented in this paper. The resolution of several kinds of overlapped peaks with noise simulated by computer has been performed and discussed in details. This method has been used for resolving of the UV–vis overlapped spectrum. The results indicate that the proposed algorithm can been used to resolve overlapped spectra effectively and satisfactorily.

Despite the increasing number of applications of biosensors in many fields, the construction of a steady biosensor remains still challenging. The high selectivity and stability of molecularly imprinted polymers for the template molecule make them ideal alternatives as recognition elements for sensors. In this work, the fabrication and characterization of biosensor based on molecularly imprinted electrosynthesized polymers is reported as the first case of imprinting sorbitol. A relevant molecularly imprinted film is prepared by o-phenylenediamine (o-PD) using the electrochemical method. Quartz crystal microbalance is employed as a sensitive apparatus of biosensor for the determination of sorbitol. An equation is deduced to characterize the interaction between molecularly imprinted films and the template. A linear relationship between the frequency shift and the concentration of analyte in the range of 1–15 mM was found. The detection limit is about 1 mM.

The Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectra of 2-nitro-tetraphenylporphyrin (2-NO2-TPP), nickel-2-nitro-tetraphenylporphyrin (Ni-2-NO2-TPP), zinc-2-nitro-tetraphenylporphyrin (Zn-2-NO2-TPP) and copper-2-nitro-tetraphenylporphyrin (Cu-2-NO2-TPP) were acquired for the first time and carefully assigned and discussed. The effects of a β-NO2 group and the influence of the central metal on the molecular symmetry and vibrational spectra of the porphyrin macrocycle were also examined. The bands at 1323–1339, 1516–1526 and 961–971 cm−1 were attributed to the symmetric and asymmetric stretching vibration of the NO2 group and to the stretching vibration of the CβN bond, respectively, which connects the NO2 group with the β-carbon of the porphyrin macrocycle. These bands can act as a marker to distinguish β-NO2 TPPs from other β-substituent TPPs. Cu-2-NO2-TPP has a C4ν molecular symmetry, which is different from those of Ni-2-NO2-TPP and Zn-2-NO2-TPP, i.e. D4h.

A highly sensitive piezoelectric HBV DNA biosensor has been developed based on the sensitive mass-transducing function of the quartz crystal microbalance and the speciality of nucleic acid hybridization reaction. HBV nucleic acid probe was immobilized onto the gold electrodes of a 9 MHz AT-cut piezoelectric quartz crystal with the polyethyleneimine adhesion, glutaraldehyde cross-linking (PEI-Glu) method or the physical adsorption method. The coated crystal with the PEI-Glu method to immobilized HBV nucleic acid probe showed the better results than the physical adsorption method with respect to sensitivity reproducibility and stability. The frequency shifts of hybridization have better linear relationship with the amount of HBV DNA, when the amount was in range 0.02–0.14 μg/ml. The crystal could be regenerated nearly five times without perceptible decrease of sensitivity.

The effect of acetonitrile (ACN) on the low-affinity interaction between human serum albumin (HSA) and ibuprofen (IBP) was studied using 1H-NMR techniques. Both chemical shift and relaxation measurements showed the addition of ACN to the solutions decreased the binding affinity of IBP to HSA and reduced the hydrophobic interaction between them. The self-diffusion coefficients of IBP were measured as a function of the drug concentration at different ACN concentrations. The association constant, Ka, for ligand–HSA complexes and the number of binding sites, n, are evaluated by the application of Langmuir isotherm. The results indicated that the value of n was about 38 without ACN, and about 26 with ACN concentration 12% (v/v%). The decreased binding capacity of IBP to HSA in the presence of ACN was mainly attributed to the competition of ACN with IBP to the low-affinity binding sites of HSA molecule.

A needle-electrochemical microsensor measuring system was established in order to study the pO2 characteristics of the acupuncture points. Before being used in vivo, the needle-electrochemical microsensor was tested in the in vitro experiments and was proved stable and good in voltametric characteristics. The in vivo measurements showed that the pO2 in the acupuncture points of rabbits was remarkably higher than that in the non-acupuncture points (1 cm apart from the acupuncture points). The results indicated that the needle-electrochemical microsensor has a good performance in measuring the pO2 in vivo. The work contributes to the study of the needle-electrochemical microsensor for measuring pO2 in vitro and in vivo, and supplies useful information and evidence for the acupuncture and meridian mechanism.

Copper(II), zinc(II), cobalt(II) and cobalt(III) complexes of N-d-glucosamine β-naphthaldehyde (C17H19O6N, NG) and glycine were synthesized. The four novel metal complexes, Cu(II)C19H28O11N2(CuGNG), Zn(II)C19H24O9N2(ZnGNG), Co(II)C19H28O11N2(Co(II)GNG) and Co(III)C21H29O12N2(Co(III)GNG) were characterized by means of infrared (IR), electronic absorption spectroscopy and NMR etc. The surface-enhanced Raman spectra of the four complexes and their interaction with DNA were studied. By comparison of the surface-enhanced Raman spectra (SERS), the information of the four complexes’ SER active sites and adsorption orientation were obtained. Combined with fluorescence spectra of Ethidium bromide (EthBr) DNA system, we concluded that none of the four complexes intercalate into DNA and that the presence of the glycine ligand lowered the anticancer activity of NG series complexes.

The Fourier-transform Raman (FT-Raman), infrared (FT-IR), and UV-visible absorption spectra of four dipyrrinones and two mesobilirubins have been investigated in the solid state and in CH2Cl2 solutions. A detailed spectral analysis, assignment and discussion of these spectra are presented. The bands at 1735–1738, 1691–1707 and 1359–1377 cm−1 which were assigned to the stretching vibrations of the COC and COH and symmetric deformation of CH bonds, respectively, can act as a marker to distinguish the compounds of this class. The striking differences between the spectra of the compounds suggest that mesobilirubin XIIIα is tending to adopt as ridge-tile conformation, rather than linear conformation.

The vibrational spectroscopy of novel biliverdin compounds were studied by Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectroscopy. The effects of type, length and position of substituents at C(8) and C(12) or C(1) and C(19) of tetrapyrroles on FT-Raman and FT-IR spectra of these compounds, are discussed. The marker bands are developed in order to distinguish between etiobiliverdin and mesobiliverdin.

The structure and composition of the yolk spherocrystal, a biomineral developed in the egg yolk sac during the incubation of a chicken embryo, were investigated through various modern analytical methods. Additionally, inside the yolk sac, yolk liquid crystal, a liquid crystalline phase of lipid developed during the incubation of the embryo, was found and investigated. The spherocrystal was found to be a composite composed of calcium carbonate (vaterite and calcite, primarily the former) and the yolk liquid crystal, which is believed to act as an organic template for spherocrystals mineralization, in a concentric multi-layered sphere structure. Moreover, the yolk liquid crystal was found to have a concentric multi-layered spherical structure and a composition consistent with lecithin. We believed that the spherocrystals function as a reservoir for the storage of calcium in the egg yolk sac during the development of the embryo.

•Ag+-triggered aggregation of peptide-AuNPs is newly proposed.•The principle depends on the behavior of Ag+-induced folding structure of peptides.•Ultrasensitive detection of silver ions with potential as practical application in complex water samples.•We present a simple, rapid, original method with excellent selectivity.In this article, we for the first time present an original and ultrasensitive assay to detect Ag+ ions, with which the aggregation of the given peptide-modified gold nanoparticles (peptide-AuNPs) can be triggered by the interaction between peptides and Ag+. The approach has rarely been used in the colorimetric determination of Ag+, because the mechanism of the above-mentioned interaction has not been studied through. In our assay, the principle of this interaction was investigated. Moreover, we applied it in the design of an extremely sensitive sensor for Ag+ detection with great selectivity. It is the Ag+-induced folding structure of the peptides that leads to the aggregation of peptide-AuNPs. The aggregation involves the formation of 4-coordinated complexes between Ag+ and peptides via bonding with the carbonyl oxygen and the nitrogen of the α-amino group in the peptides. The result shows that Ag+ ions can be selectively detected as low as 7.4 nM with a linear range of 10–1000 nM. Compared with other approaches, the proposed approach demonstrates superior simplicity, sensitivity, stability and time-saving. Furthermore, the biosensor excels in the practical application in water samples (e.g., lake, tap and drinking water) owing to its non-interference and on-site rapid determination.

In the present study, silica nanoparticles with resonance Raman scattering (RRS) properties were utilized to construct a novel resonance Raman scattering tag for in vivo cellular imaging. β-Carotene, a native pigment insoluble in water, was for the first time encapsulated in silica nanoparticles through a simple one-step procedure in which β-carotene was enriched in the micelle of cetyltrimethylammonium bromide (CTAB) and simultaneously enclosed during the hydrolysis of tetraethylorthosilicate (TEOS). The particles were characterized by using X-ray diffraction, transmission electron microscopy (TEM), and Raman spectroscopy. Results showed that the size distribution of β-carotene doped silica nanoparticles (CSNPs), which were highly dispersible in aqueous solution, was fairly uniform in the range of 60 to 200 nm. Due to the advantages of highly stable and repeatable RRS signals of doped β-carotene, a simple cellular imaging approach based on this novel Raman tag has been preliminarily achieved. This paper demonstrated that resonance Raman scattering tags are important candidates for biological applications considering their high biocompatibility and spectral stability.

We describe a highly sensitive and spectrally stable surface-enhanced Raman scattering (SERS) tag for live cell imaging based on carbon-encapsulated gold nano-aggregates (CEGNAs). Our findings reveal that controlling the synthesis of the gold nano-aggregate core can be achieved under the mediation of cetyltrimethylammonium bromide (CTAB) through electrostatic forces and hydrophobic interactions, and as the number of particles in the aggregates increase, the relative SERS activity also increases hugely.

A simple method of fabricating shape-tunable Au nanopeanuts from Au–Ag core–shell nanoparticles based on both galvanic replacement and reagent reduction is described.

A simple, toehold-mediated two-way input DNA machine has been developed. Utilizing symmetric and asymmetric protector sequences, INH, XOR logic gates and a half-subtractor are designed based on this two-way structure.

A recent study reported by Higuchi's group has shown that Pt–DNA complexes possess peroxidase enzymatic activity similar to natural peroxidases. In this study, we prepared Pt–DNA complexes and demonstrated their use in catalyzing the oxidation of a peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to the oxidized product which provided a colorimetric detection of H2O2. As low as 3.92 × 10−4 mol L−1 H2O2 could be detected with a linear range from 9.79 × 10−4 to 1.76 × 10−2 mol L−1via our method. Furthermore, PVDF membranes were employed to increase sensitivity and decrease the detection limit of H2O2, enabling a two-fold improvement in the detection sensitivity as compared with the above counterparts. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepared Pt–DNA complexes. We realized the test of glucose as low as 10−7 mol L−1 by the color change, which was comparable to or even better than the existing methods, and identified the concentration of glucose in Sprite with the naked eye without referring to any sophisticated apparatus. The detection platforms for H2O2 and glucose developed in the present work showed great potential for applications in the future.

By employing two-dimensional and water-soluble graphene oxide (GO), a turn-on sensor was developed for the label-free detection of Zn2+ based on Zn2+-induced G-quadruplex (G4) formation. Indicated using the G4-binding ligand thiazole orange (TO), the enhanced fluorescent signal could be generated only when the guanine-rich DNA was excluded from the surface of GO due to the formation of a G4 induced by Zn2+. The results have shown that the method can be utilized for the detection of Zn2+ in a linear range from 0–30 μM with a detection limit of 0.71 μM. The real sample testing conducted in serum samples demonstrated its practical potential in biological analysis.

Novel functional oligonucleotides, especially DNAzymes with RNA-cleavage activity, evoke current research interest increasingly due to their potential applications in therapeutics and sensors. One of the most attention-attracting is the lead-specific DNAzyme, which is composed of an enzyme strand 17E and a substrate strand 17S, addition of Pb2+ enables the DNAzyme to cleave its substrate. In this study, we took advantage of the unique optical properties of a water-soluble cationic polythiophene (PT) and designed a fluorometric sensing assay for the detection of Pb2+. A simple “mix-and-detect” approach enabled the detection of Pb2+ within 20 minutes due to the distinguishable optical properties of PT–dsDNA and PT–ssDNA. As low as 10 nM Pb2+ could be detected with a detection range from 10 nM to 100 μM via this method. Furthermore, this method was highly selective and only minimally perturbed by nonspecific metal ions. Since common steps such as modification and separation could be successfully avoided, this simple, sensitive, specific, and cost-effective approach showed great potential applications in environmental monitoring, waste management and clinical toxicology.

A bi-detection system integrated by laser-induced fluorescence (LIF) and retro-reflected beam interference (RBI) based refractive index was established and applied to simultaneously determine erythrosine and sucrose in candy floss. The system realized separation-free analysis of candy floss without prior concentration steps.

With the technical progress in lasers, charge coupled device detectors, and fiber-optic probes, Raman spectroscopy (RS) is enjoying a strong resurgence in the field of biomedical science, especially in disease diagnosis. During this time we have witnessed more and more in vitro and in vivo applications of RS, and increasingly frequent reports of its utility. RS enables the extraction of biochemical signatures from biological tissues, and in conjunction with different statistic algorithms, the spectral data with various pathologic attributions can be differentiated and classified depending on their spectral differences, e.g., peak area, peak height or peak shape. This makes RS a potential clinical analytical technique for rapid and non-destructive diagnosis of human diseases. This paper is a review of the biomedical applications of Raman spectroscopic techniques in diagnostics. First, a brief illumination of RS instrumentation and algorithms for data analysis is introduced. Then wide utilization of RS in disease diagnosis is reviewed categorized by different tissues and organs, including brain, eye, body surface organs (breast, skin), abdominal organs (stomach, esophagus, colon, liver), thoracic organs (arteries, lung), reproductive and urinary organs (prostate, cervix, bladder) and hard tissue (bone, teeth). Some other work from our group are also introduced.

Novel three-dimensional (3D) nano-assemblies of noble metal nanoparticle (NP)–infinite coordination polymers (ICPs) are conveniently fabricated through the infiltration of HAuCl4 into hollow Au@Ag@ICPs core–shell nanostructures and its replacement reaction with Au@Ag NPs. The present 3D nano-assemblies exhibit highly efficient and specific intrinsic oxidase-like activity even without adding any cosubstrate.

A simple, rapid colorimetry for DNA detection based on non-aggregated gold nanoparticles and magnetic beads has been developed with high selectivity and sensitivity.