Single nucleotide polymorphisms (SNPs) are the most fundamental internal causes for many genetic diseases. However, the location information on SNPs in a specific DNA sequence is not well acquired through current SNPs detection methods, except for accurate DNA sequencing. Here we report a fluorescence enhancement phenomenon in the process of two silver nanoclusters (AgNCs) approaching closely to form a nanocluster dimer (NCD). The fluorescence intensity is sensitive to the distance between two AgNCs; therefore, the NCD lights into different fluorescence intensities upon binding SNPs targets with mismatched bases at different positions. Interestingly, the fluorescence intensities of the NCD decrease linearly when the position of single mismatched base moves gradually from the middle point to the end of the target DNA. The NCD is a single probe acting as a universal platform to pinpoint various SNP positions. With this single probe, we cannot only identify the existence of SNPs but also pinpoint the location of a specific single mismatched base in the adjacent positions. This strategy is feasible to detect specific gene point mutations in clinical samples.

A combinatorial immunoassay method for biomarker detection based on a stable isotope tagging strategy was proposed. A multiplex immunoassay of 12 proteins could be achieved simultaneously and a combinatorial immunoassay was explored, which would be expected to satisfy the requirements of personalized detection.

ICP-MS-based multiplex immunoassays have the advantages of low sample consumption and minimized repetitions of tedious procedures. However, this technique is seldom used in clinical tests because of the complicated matrix effect in clinical samples and the discrimination effect to the target proteins. In this work, we developed an ICP-MS-based magnetic immunoassay by using magnetic beads as highly efficient affinity probes and optimizing the magnetic immunoassay parameters. We applied this method to the simultaneous determination of three crucial gynecological tumor biomarkers that are vital in the prognosis and monitoring of the recurrence of breast cancer and ovarian cancer. The measurable ranges of HER-2, HE4 and CA15-3 were 12–1000 ng mL−1, 8–2000 pmol L−1 and 5–200 U mL−1, with detection limits (3σ) of 3.94 ng mL−1, 2.59 pmol L−1 and 1.62 U mL−1, respectively. The relative standard deviations (RSDs) were 2.61% for HER-2 at 15 ng mL−1, 4.90% for HE4 at 25 pmol L−1 and 6.68% for CA15-3 at 10 U mL−1, indicating good accuracy of the method. The spiking test indicated that the present method had a low matrix effect. Under optimized conditions, the simultaneous detection of HER-2, HE4, and CA15-3 in clinical serum samples was performed and the values correlated well with those obtained by the time resolved fluorescence immunoassay (r2 = 0.9568 for HER-2, 0.9485 for HE4, 0.9133 for CA15-3). The present work shows that the ICP-MS-based magnetic immunoassay meets the requirements for the quantification of three crucial gynecological tumor biomarkers in real clinical tests.

A colorless and nonfluorescent spirolactam derivative, RhB-R12K, was synthesized by amide condensation between the carboxyl group of rhodamine B (RhB) and the amino group of cell-penetrating peptide (CPP). The fluorescence intensity of RhB-R12K sharply increased as the pH value decreased from 8.0 to 4.9, demonstrating sensitive and reversible response to intracellular pH distribution. This CPP probe was completely water soluble, had low cytotoxicity, was membrane permeable, and was suitable for pH measurement in various organelles by choosing organelle-specific CPP sequences. Interestingly, CPPs acted not only as carriers but also as indispensable parts of fluorophores here. The presence of active groups on the peptides potentially allows for modification with additional dyes to construct multifunctional and ratiometric probes for cell imaging.

•The protein synthesis rates and spatial distribution in normal and cancerous cells.•The responding to anticarcinogen stimulation in normal and cancerous cells.•Distinguish cancerous and normal cells, benefit the diagnosis of cancer.•Help to evaluate the curative effect of drugs.Some anticarcinogen could treat cancers through regulating the synthesis and degradation of proteins. Therefore, the rules of newly synthesized proteins would be used to evaluate the effect of anticarcinogen. In this study, we coupled noncanonical amino acid tagging with click reaction to label the newly synthesized proteins in normal cells and cancerous cells. We studied the influence of six different drugs on the protein synthesis. The results showed the differences of protein synthesis rate and spatial distribution in normal cells and cancerous cells, as well as their different responding to anticarcinogen stimulation. This approach could help us to understand the growth of proteins and distinguish cancerous cells from normal cells, which would benefit the diagnosis and monitoring of cancer, as well as evaluating the curative effect of drugs. Based on this strategy, more significant biological process about newly synthesized biomolecules would be studied in-depth.Some anticancer drugs could treat cancers through regulating the synthesis and degradation of proteins. We study the quantity and distribution of newly synthesized proteins and investigate the modulation of anticancer drugs in normal and cancerous cells by click chemistry. The differences in protein synthesis and responding to anticarcinogen stimulating in normal and cancerous cells may provide a new vision to diagnosis and monitoring cancer, as well as evaluate the curative effect of drugs.Figure optionsDownload full-size imageDownload high-quality image (247 K)Download as PowerPoint slide

•A facile design strategy based on AuNCs is proposed to detect hydrogen sulfide by ratiometric way•The resulting nanohybrid probe shows a broad linear range of 7–100 μM and a low detection limit of 0.73 μM.•The probe possesses high selectivity, stability against pH change and longtime light illumination.•The probe can be applied to detect H2S in biological samples with perfect recoveries.The emergence of ratiometric fluorescent probes have offered more convincing results to the bioanalytical field of research. In particular, using nanoparticles as scaffolds for the construction of ratiometric systems has received increasing attention. In this work, a novel design strategy was implemented for ratiometric sensing of hydrogen sulfide (H2S), in which bovine serum albumin templated gold nanoclusters (BSA-AuNCs) was served as the internal reference fluorophore and HSip-1, a azamacrocyclic Cu2+ complex based fluorescent probe toward H2S, acted as both the signal indicator and specific recognition element. Under single wavelength excitation, the nanohybrid probe HSip-1@AuNC emitted dual fluorescence at 519 and 632 nm, coming from HSip-1 and AuNCs respectively. The effective fluorescence response of organic dye to H2S and constant fluorescence of AuNCs enabled the proposed HSip-1@AuNC to achieve the ratiometric measurement with a dynamic linear range of 7–100 μM and a detection limit of 0.73 μM. This probe also possesses high selectivity, stability against pH change and continuously light illumination. In addition, we provided HSip-1@AuNC as a valuable tool to analyze sulfides in serum samples and perfect recoveries verified its potential in biological applications.Download full-size image

Herein we report a novel strategy for the detection and identification of proteins using unmodified noble metal nanoparticles. Five gold nanoparticles (AuNPs) and two silver nanoparticles (AgNPs) with different sizes were utilized as sensing elements to create a colorimetric sensor array. In the presence of proteins, the UV-vis absorbance of the noble metal nanoparticles changed due to the interactions between the protein and nanoparticles, producing distinct absorbance response patterns which can be visually detected by the naked eye. The color pattern of the array is a unique “fingerprints” for each protein sample, which can be differentiated by linear discriminant analysis (LDA). Ten different proteins at concentrations of 0.5, 5 and 50 μM have be successfully discriminated. Moreover, the array was also able to discriminate different bacteria at a concentration of 0.05 OD in 200 μL, as well as cancer cells at the level of 5000 cells in 200 μL. This work demonstrates that an unmodified noble metal nanoparticle-based protein detection array has potential for applications in medical diagnostics.

A new “turn-on” fluorescent probe, composed of a protected phenol group with a p-nitrobenzyl moiety that functions as a latent donor and conjugated with two benzo[f]indolinium acceptors, was developed and applied for imaging nitroreductase (NTR) in hypoxic tumor cells. Nitrobenzyl moieties on the substrate can be conveniently converted into aminobenzyl groups with a nitroreductase-catalyzed reaction in the presence of reduced nicotinamide adenine dinucleotide (NADH). This is followed by a cleavage reaction and the release of the free phenol moiety, which is manifested in enhanced fluorescence intensity during the detection process. Our experimental results show that the NTR detection ability is over 100 equivalents of other biological reductants (1 mM), whereas the confocal fluorescence imaging of tumor cells indicates the possibility of its application in biomedical research fields for tumor hypoxia diagnosis.

We present a simple, selective and label-free sensor for detecting DNA based on the fluorescence of DNA–silver nanoclusters (DNA–Ag NCs). Two kinds of DNA–Ag NCs with different oligonucleotide sequences can bind together as a DNA–Ag NC pair by hybridization and show strong fluorescence emission at a wavelength of 624 nm. In the presence of the target DNA, the competing reaction of DNA hybridization occurs, and the formed DNA–Ag NC pairs decrease, exhibiting weak fluorescence emission. The fluorescence intensity decreases linearly with the increase of the target DNA concentration in the range of 0.20–10.00 μM with a limit of detection of 0.13 μM. The relative standard deviation (RSD) values obtained from the same batch of H1N1 target DNA were 1.80%, 0.30% and 2.90% at 2.0 × 10−7, 4.0 × 10−7 and 6.0 × 10−7 mol L−1, respectively. The coexisting random DNAs do not interfere with the detection at a concentration of 5.0 × 10−6 mol L−1. With this sensor, we successfully detected H1N1 target DNA and the results indicated that our method is reliable and has the potential for real sample application.

A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

A multiplex DNA assay based on nanoparticle (NP) tags detection utilizing single particle mode inductively coupled plasma mass spectrometry (SP-ICP-MS) as ultrasensitive readout has been demonstrated in the article. Three DNA targets associated with clinical diseases (HIV, HAV, and HBV) down to 1 pM were detected by DNA probes labeled with AuNPs, AgNPs, and PtNPs via DNA sandwich assay. Single nucleotide polymorphisms in genes can also be effectively discriminated. Since our method is unaffected by the sample matrix, it is well-suited for diagnostic applications. Moreover, with the high sensitivity of SP-ICP-MS and the variety of NPs detectable by SP-ICP-MS, high-throughput DNA assay could be achieved without signal amplification or chain reaction amplification.

The discrimination of the type of cancer cells remains challenging due to the subtle differences in their expression of membrane receptors. In this work, we developed a multicolor cell imaging method for distinguishing the type of cancer cells with fluorophore-tagged aptamers. We found that the interaction between aptamers and cancer cells was affected by both of the sequence of aptamers and the labeled dyes. As the co-ownership of biomarkers for different cancer cell lines, the fluorophore-tagged aptamers interacted with different cancer cell lines in different degree, resulting in a distinct color to discriminate the type of cancer cells at single cell level. Taking advantage of the cross-reactive ability of the fluorophore-tagged aptamers, we could not only distinguish the cancerous cells quickly from large quantities of noncancerous cells, but also identify the type of the cancerous cells. This work has potential application for cancer diagnostic and therapy in the future.

The fluorescence, catalytic activity and assembly behavior of GO could be simultaneously changed after interaction with proteins, leading to distinct response patterns related to each specific protein. Based on the phenomenon, a triple-channel optical sensor has been proposed in the present communication for protein discrimination with GO as a single sensing element.

We developed a colorimetric sensor array with reported protein aptamers as nonspecific receptors. We found that different target proteins could make the aptamer-protected gold nanoparticles (AuNPs) exhibit different aggregation behaviors in the presence of a high concentration salt and cause various color change. On the basis of this phenomenon, we applied a series of reported protein aptamers as a receptor array obtaining a distinct response pattern to each target protein. Seven proteins have been well distinguished with the naked eye at the 50 nM level. Cancerous human cells have also been discriminated from noncancerous cells. This method is simple, label-free, and sensitive. It will broaden the application filed of plasmonic nanoparticle-based sensors and give a new direction of developing sensitive array sensing systems.

The method for the localization of bioactive molecules in plants is highly needed since it provides a fundamental prerequisite for understanding their physiological and ecological functions. Here, we propose a simple method termed in vivo nanoelectrospray for the localization of bioactive molecules in plants without sample preparation. A capillary is partly inserted into the plant to sample liquid from a highly located region, and then, a high voltage is applied to the plant to generate an electrospray from the capillary tip for mass spectrometry analysis. Using this method, bioactive molecules such as saccharides, glycoalkaloids, flavonoids, organic acids, and glucosinolates (GLs) are detected in the target regions of living plants or fresh fruits. Original information for endogenous chemicals including liable molecules in plant can be obtained. A sketchy three-dimensional distribution of glycoalkaloids in a cherry tomato has been obtained. The present work provides a powerful tool for the study of bioactive molecules in a living plant by mass spectrometry.

Extracting multidimensional information from an individual transducer simultaneously is a promising alternative sensing strategy to traditional sensors. Here, we proposed a novel dual channel sensing method with simultaneously recording conductivity change of sensing material and chemiluminescence emission during catalytic oxidation of volatile organic compounds on tin oxide nanoparticles. The orthogonal and complementary electrical and optical signals have been obtained for each compound, which have been applied to discriminate 20 volatile organic compounds using hierarchical cluster analysis (HCA). Unknown samples from three groups at concentrations of 0.2%, 0.6%, and 1.0% have been successfully classified using linear discriminant analysis (LDA) with accuracies of 98.3%, 96.7%, and 98.3%, respectively. This dual channel sensing mode is a complement of semiconducting type gas sensors and quite promising for the development of chemical sensor arrays with multimode transducing principles.

The development of material science increasingly calls for rapid characterization methods with low limits of detection and high spatial resolution. Here we report a depth profile analysis method for thin layer coatings by combining low temperature plasma (LTP) probe with inductively coupled plasma mass spectrometry (ICP-MS). The LTP probe with diameter of several tens of micrometers served as a tool for mass removal, which is generated by the discharge in a quartz capillary at ambient condition. The sample material is ablated by the LTP probe and converted into an aerosol, and transported by a carrier gas flow to the ICP-MS, where the decomposed and ionized aerosol particles are analyzed with high sensitivity. Scanning electron microscope (SEM) micrographs reveal that the trace after ablation by the LTP probe is a hole with a diameter less than 10 μm. A lateral resolution of approximately 200 μm has been achieved by analyzing an electron component with interval metal stripes. Depth profiling of a 100 nm single layer sample and a multiple layer sample (100 nm Al/250 nm SiO2/100 nm Au/50 nm Cr) on a silicon substrate have been successfully performed at ambient condition. The present method offers unique advantages in terms of high spatial resolution, fast analysis speed and ease of implementation. It might be considered a complementary technique to existing depth profiling methods such as GD-MS/OES, AES, and SIMS. In addition, the simple-to-fabricate LTP probe is easily coupled to various other elemental analysis tools for thin layer or direct solid sample analysis in micro area.

High-throughput screening of catalysts could dramatically improve performance and reduce costs in the discovery and study of various catalysts. Here we report a cataluminescence-based array imaging as a high-throughput screening technique in the combinatorial discovery of active catalysts for CO oxidation. This strategy is based on the fact that the CO oxidation generates cataluminescence emission on the surface of nanomaterials, whose intensity is correlated to the activity of the catalyst. To demonstrate the feasibility of the cataluminescence-based array imaging for high-throughput screening of catalysts, different nanosized metal catalysts supported on TiO2 nanoparticles were prepared. These catalysts include monometallic Au, Pt, and the bimetallic Au−Pt heteroaggregate catalysts, at total metal loadings of 0.5%, 1.0%, and 2.5%, and with atomic ratios of 1:1, 1:2, and 2:1 (Au/Pt). A 4 × 4 array was integrated by depositing these nanosized catalysts onto the ceramic chip, and the brightness of each spot in the image was recorded. The catalytic activities of those catalysts for the CO oxidation were evaluated parallelly by both the cataluminescence imaging and the gas chromatography method. The correlation coefficient is 0.914 for the two techniques, indicating that the cataluminescence imaging technique can be applied for the evaluation of the catalytic activities. Moreover, fast evaluation of multiple catalysts at a series of working temperature can be achieved by this cataluminescene-based array imaging. With the development of nanotechnology as well as the catalyst industry, the cataluminescence-based array imaging will address its importance in the high-throughput screening of catalysts.

Real-time and in-situ monitoring of ongoing chemical reactions by mass spectrometry was achieved by simply directing the low-temperature plasma (LTP) to the surface of the reaction system for analyte desorption and ionization without any sample pretreatment.

A simple and easy-to-build high-throughput analysis system was constructed. The system consisted of three major components: (1) a multichannel device with 16 parallel capillaries, (2) a desorption electrospray ionization (DESI) source, and (3) a linear ion trap mass spectrometer. When analyses were performed, the multichannel device was moved horizontally on a translation stage controlled by a step motor. Our design expands the functions of DESI, in which the liquid sample in capillary was driven out by the nebulizing gas, ionized, and then transferred to a mass spectrometer. To assess the high-throughput performance of the system, 5 mg/L 1,3-diethyl-1,3-diphenylurea (DDU) solution and 10 mg/L angiotensin I solution were alternatively loaded into the reservoirs and capillaries in the multichannel device. Results indicated that analyses of the all the samples in 16 capillaries were completed within 1.6 min, which means a throughput of 600 samples/h. Reactive DESI experiment was also successfully performed with this system to show the feasibility of online derivatization. The relative standard deviations for a single capillary and five identical capillaries were 7.6 (n = 16) and 12.3%, respectively. Linear relative abundance response was achieved for DDU (r=0.9971).

A new “turn-on” fluorescent probe, composed of a protected phenol group with a p-nitrobenzyl moiety that functions as a latent donor and conjugated with two benzo[f]indolinium acceptors, was developed and applied for imaging nitroreductase (NTR) in hypoxic tumor cells. Nitrobenzyl moieties on the substrate can be conveniently converted into aminobenzyl groups with a nitroreductase-catalyzed reaction in the presence of reduced nicotinamide adenine dinucleotide (NADH). This is followed by a cleavage reaction and the release of the free phenol moiety, which is manifested in enhanced fluorescence intensity during the detection process. Our experimental results show that the NTR detection ability is over 100 equivalents of other biological reductants (1 mM), whereas the confocal fluorescence imaging of tumor cells indicates the possibility of its application in biomedical research fields for tumor hypoxia diagnosis.

A multiplex ICP-MS-based miRNA assay with duplex-specific nuclease amplification using bifunctional oligonucleotide probes was proposed. A multiplex assay of miR-141, let-7d, and miR-21 could be achieved simultaneously.

We present a simple, selective and label-free sensor for detecting DNA based on the fluorescence of DNA–silver nanoclusters (DNA–Ag NCs). Two kinds of DNA–Ag NCs with different oligonucleotide sequences can bind together as a DNA–Ag NC pair by hybridization and show strong fluorescence emission at a wavelength of 624 nm. In the presence of the target DNA, the competing reaction of DNA hybridization occurs, and the formed DNA–Ag NC pairs decrease, exhibiting weak fluorescence emission. The fluorescence intensity decreases linearly with the increase of the target DNA concentration in the range of 0.20–10.00 μM with a limit of detection of 0.13 μM. The relative standard deviation (RSD) values obtained from the same batch of H1N1 target DNA were 1.80%, 0.30% and 2.90% at 2.0 × 10−7, 4.0 × 10−7 and 6.0 × 10−7 mol L−1, respectively. The coexisting random DNAs do not interfere with the detection at a concentration of 5.0 × 10−6 mol L−1. With this sensor, we successfully detected H1N1 target DNA and the results indicated that our method is reliable and has the potential for real sample application.

The fluorescence, catalytic activity and assembly behavior of GO could be simultaneously changed after interaction with proteins, leading to distinct response patterns related to each specific protein. Based on the phenomenon, a triple-channel optical sensor has been proposed in the present communication for protein discrimination with GO as a single sensing element.