In this work, we developed the surfactant-free aqueous synthesis of novel polyethylene glycol (PEG) coated Ba2GdF7:Yb3+, Er3+ upconversion nanoparticles (named as, Ba2GdF7:Yb3+, Er3+@PEG UCNPs) for in vivo multimodality imaging including upconversion luminescence (UCL), X-ray computed tomography (CT), and T1-weighted magnetic resonance (MR). The as-prepared Ba2GdF7:Yb3+, Er3+@PEG UCNPs not only present bright UCL and reasonably high CT/MR enhancements but also exhibit excellent colloidal stability, inappreciable cytotoxicity, and negligible organ toxicity. In particular, the Ba2GdF7:Yb3+, Er3+@PEG UCNPs emit red UCL with high intensity in the tumor site after intravenous injection via the tail vein of a nude mouse. The Ba2GdF7:Yb3+, Er3+@PEG UCNPs as contrast agents exhibit high-performance for in vivo trimodality (UCL/CT/MR) imaging of a tumor during HepG2 tumor-bearing nude mouse experiments.Keywords: Ba2GdF7:Yb3+, Er3+@PEG UCNPs; in vivo trimodality imaging; red emission;

Matrix metalloproteinases (MMPs) are closely associated with cancer cell invasion and metastasis. Herein, a fluorescence resonance energy transfer (FRET)-peptide microarray-based metal enhanced fluorescence (MEF) assay is proposed for multiple and sensitive profiling of MMPs activities on a novel Au/Ag@SiO2 substrate. The Au/Ag@SiO2 substrate is prepared by electroless deposition of silver on gold nanoparticle (GNP) seeds, followed by SiO2 shell coating and surface functionalization. The specific FRET peptides are spotted on the Au/Ag@SiO2 substrate to sensitively detect MMPs (MMP-2, -3, -7, -9, -14) via fluorescence recovery by the MMP cleavage of quenched peptide motifs and further enhanced by MEF. Under the optimal conditions, the limits of detection are 12.2 fg mL–1 for MMP-2, 60 pg mL–1 for MMP-3, 0.22 pg mL–1 for MMP-7, 102 fg mL–1 for MMP-9, and 0.68 ng mL–1 for MMP-14, respectively. The practicability of the FRET-peptide microarray-based MEF assay is demonstrated by profiling of multiplexed MMPs activities in various cell lines and clinical thyroid tissue samples of papillary thyroid carcinoma (PTC) patients and thyroid nodules (TN) patients, and satisfactory results are obtained.

Matrix metalloproteinases (MMPs) are important biomarkers and potential therapeutic targets of tumor. In this report, a peptide microarray-based fluorescence assay is developed for MMPs inhibitors evaluation through immobilization of biotin-modified peptides on the poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) (P(GMA-HEMA)) brush-modified glass slides. After biotin is recognized with cyanine 3 (Cy3)-modified avidin (Cy3-avidin), the microarrays can produce strong fluorescence signal. The biotin moieties detach from microarray, when the biotin-modified peptide substrates are specially cleaved by a MMP, resulting in decreased fluorescence intensity of the microarray. The decreasing level of fluorescence intensity is correlated with the MMP inhibition. Nine known MMP inhibitors against MMP-2 and MMP-9 are evaluated by the assay, and the quantitative determination of inhibitory potencies (half maximal inhibitory concentration) are obtained, which are comparable with the literatures. Two biocompatible fluorogenic peptides containing MMP-specific recognition sequences and FAM/Dabcyl fluorophore-quencher pair are designed as activatable reporter probes for sensing MMP-2 and MMP-9 activities in cell and in vivo. The peptide microarray-based results are well verified by the cell inhibition assay and in vitro fluorescence imaging, and further confirmed by the in vivo imaging of HT-1080 tumor-bearing mice.Keywords: fluorescence imaging; in vivo imaging; inhibition; matrix metalloproteinases; peptide microarray; polymer brush substrate;

Matrix metalloproteinases (MMPs) are important biomarkers and potential therapeutic targets of tumor. In this report, a peptide microarray-based fluorescence assay is developed for MMPs inhibitors evaluation through immobilization of biotin-modified peptides on the poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) (P(GMA-HEMA)) brush-modified glass slides. After biotin is recognized with cyanine 3 (Cy3)-modified avidin (Cy3-avidin), the microarrays can produce strong fluorescence signal. The biotin moieties detach from microarray, when the biotin-modified peptide substrates are specially cleaved by a MMP, resulting in decreased fluorescence intensity of the microarray. The decreasing level of fluorescence intensity is correlated with the MMP inhibition. Nine known MMP inhibitors against MMP-2 and MMP-9 are evaluated by the assay, and the quantitative determination of inhibitory potencies (half maximal inhibitory concentration) are obtained, which are comparable with the literatures. Two biocompatible fluorogenic peptides containing MMP-specific recognition sequences and FAM/Dabcyl fluorophore-quencher pair are designed as activatable reporter probes for sensing MMP-2 and MMP-9 activities in cell and in vivo. The peptide microarray-based results are well verified by the cell inhibition assay and in vitro fluorescence imaging, and further confirmed by the in vivo imaging of HT-1080 tumor-bearing mice.Keywords: fluorescence imaging; in vivo imaging; inhibition; matrix metalloproteinases; peptide microarray; polymer brush substrate;

The reliable detection and monitoring of microRNAs (miRNAs) are of great significance for gaining a better understanding of the functions of miRNAs in a wide range of biological processes. In this work, a competitive DNA microarray-based resonance light scattering (RLS) assay has been developed for the multiplexed detection of miRNAs with relatively high sensitivity and selectivity. After one-step competition hybridization reactions of miRNAs and multiple single strand DNA (ssDNA) conjugated gold nanoparticles (ssDNAsn@GNPs) with immobilized ssDNA probes on the dendrimer-modified slide, the captured ssDNAsn@GNPs are further enlarged through silver deposition. The silver enlarged ssDNAsn@GNPs can generate strong RLS under white light excitation. The simultaneous detection of multiple miRNAs can be easily achieved by monitoring the RLS signal changes of microarrays. In the proof of concept experiment, eight miRNA let-7 family members are detected with high specificity down to 0.2 pM, 0.8 pM, 0.2 pM, 0.2 pM, 0.2 pM, 0.8 pM, 0.8 pM, and 0.8 pM for miRNA let-7a to 7g, and 7i, respectively. Furthermore, the expression levels of eight miRNA let-7 family members in the total RNA extracts from five cell lines have been evaluated, and satisfactory results are obtained.

In this study, a biocompatible nanotheranostic platform (termed as Fe2O3@PDA-affibody) has been constructed on the basis of coating a near-infrared light (NIR)-absorbing polydopamine (PDA) shell on oleic acid-capped superparamagnetic ferric oxide nanoparticles (Fe2O3 NPs) using the water-in-oil microemulsion method and then conjugated with affibody ZIGF1R:4551, a peptide with high affinity to tumor and a polyethylene glycol (PEG) stabilizer. The Fe2O3@PDA-affibody integrates T2-weighted magnetic resonance imaging (MRI), tumor-targeting, and magnetic field (MF)-enhanced photothermal therapy (PTT) functionalities into an all-in-one system. The Fe2O3@PDA-affibody shows high negative contrast in the MRI of an SW620 tumor bearing mouse with a decrease of 68% MRI signal, indicating that the Fe2O3@PDA-affibody can recognize tumor with high efficacy and specificity. Furthermore, a high accumulation ratio (>13.5% ID g−1) and enhanced inhibition of tumor growth are achieved under near-infrared (NIR) (808 nm) laser irradiation with the aid of an external MF focused on the targeted tumor, resulting in complete eradication of mouse-borne SW620 tumors without regrowth.

•A biosensor was fabricated for quantitative analysis of intracellular cytochrome c.•High selective recognition of Cyt c down to 20 nM is demonstrated.•The biosensor can monitor etoposide induced intracellular releasing of Cyt c.•The biosensor can monitor Cyt c mediated cell apoptosis pathway.Herein, a novel upconversion@polydopamine core@shell nanoparticle (termed as UCNP@PDA NP) -based aptameric biosensor has been fabricated for the quantitative analysis of cytochrome c (Cyt c) inside living cells, which comprises an UCNP@PDA NP, acting as an internal reference and fluorescence quenching agent, and Cy3 modified aptamer enabling ratiometric quantitative Cyt c measurement. After the hybridization of Cy3 labeled aptamer with amino-terminated single DNA on the UCNP@PDA NP surface (termed as UCNP@PDA@AP), the fluorescence of Cy3 can be efficiently quenched by the PDA shell. With the spontaneous cellular uptake of UCNP@PDA@AP, the Cyt c aptamer dissociates from UCNP@PDA NP surface through formation of aptamer-Cyt c complex, resulting in concomitant activation of the Cy3 fluorescence. High amount of Cyt c leads to high fluorescence emission, enabling direct visualization/measurement of the Cyt c by fluorescence microscopy/spectroscopy. The steady upconversion luminescent (UCL) signals can be employed not only for intracellular imaging, but also as an internal reference for evaluating intracellular Cyt c amount using the ratio of fluorescence intensity of Cy3 with the UCL intensity of UCNP. The UCNP@PDA@AP shows a reasonable detection limit (20 nM) and large dynamic range (50 nM to 10 μM, which covers the literature reported values (1–10 μM) for cytosolic Cyt c in apoptotic cells) for detecting Cyt c in buffer with excellent selectivity. In addition, the UCNP@PDA@AP has been successfully used to monitor etoposide induced intracellular releasing of Cyt c, providing the possibility for cell-based screening of apoptosis-inducing drugs.

We developed a three-dimensional (3D) polymer-brush substrate for protein and peptide microarray fabrication, and this substrate was facilely prepared by copolymerization of glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) monomers via surface-initiated atom transfer radical polymerization (SI-ATRP) on a glass slide. The performance of obtained poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) (P(GMA-HEMA)) brush substrate was assessed by binding of human IgG with rabbit antihuman IgG antibodies on a protein microarray and by the determination of matrix metalloproteinase (MMP) activities on a peptide microarray. The P(GMA-HEMA) brush substrate exhibited higher immobilization capacities for proteins and peptides than those of a two-dimensional (2D) planar epoxy slide. Furthermore, the sensitivity of the P(GMA-HEMA) brush-based microarray on rabbit antihuman IgG antibody detection was much higher than that of its 2D counterpart. The enzyme activities of MMPs were determined specifically with a low detection limit of 6.0 pg mL–1 for MMP-2 and 5.7 pg mL–1 for MMP-9. By taking advantage of the biocompatibility of PHEMA, the P(GMA-HEMA) brush-based peptide microarray was also employed to evaluate the secretion of MMP-2 and MMP-9 by cells cultured off the chip or directly on the chip, and satisfactory results were obtained.Keywords: binding of human IgG with rabbit antihuman IgG antibody; matrix metalloproteinase; peptide microarray; poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) P(GMA-HEMA); polymer-brush substrate; protein microarray

•Fabricate a hydrogel microarray on EDC/NHS activated hydrogel spots.•Studying the specific binding affinities of bacteria and lectins.•Develop a sandwiched hydrogel microarray platform for high-throughput drug screening.•The MIC values of antibiotics against S. aureus can be obtained.It still confronts an outstanding challenge to screen efficient antibacterial drugs from millions of potential antibiotic candidates. In this regard, a sandwiched microarray platform has been developed to culture live bacteria and carry out high-throughput screening antibacterial drugs. The optimized lectin-hydrogel microarray can be used as an efficient bacterial capturing and culturing platform, which is beneficial to identify spots and collect data. At the same time, a matching drug-laden polyacrylamide microarray with Luria–Bertani (LB) culture medium can be generated automatically and accurately by using a standard non-contacting procedure. A large number of microscale culture chambers (more than 100 individual samples) between two microarrays can be formed by linking two aligned hydrogel spots using LB culture medium, where live bacteria can be co-cultured with drug candidates. Using Staphylococcus aureus (S. aureus) and four well-known antibiotics (amoxicillin, vancomycin, streptomycin and chloramphenicol) as model system, the MIC (minimum inhibitory concentration) values of the antibiotics can be determined by the drug induced change of bacterial growth, and the results demonstrate that the MIC values of amoxicillin, vancomycin and streptomycin are 1.7 μg mL−1, 3.3 μg mL−1 and 10.3 μg mL−1, respectively.

DNA methylation is a crucial epigenetic modification and is closely related to tumorigenesis. Herein, a surface ligation-based high throughput method combined with bisulfite treatment is developed for analysis of methylated genomic DNA. In this method, a DNA microarray is employed as a reaction platform, and resonance light scattering (RLS) of nanoparticles is used as the detection principle. The specificity stems from allele-specific ligation of Taq DNA ligase, which is further enhanced by improving the fidelity of Taq DNA ligase in a heterogeneous reaction. Two amplification techniques, rolling circle amplification (RCA) and silver enhancement, are employed after the ligation reaction and a gold nanoparticle (GNP) labeling procedure is used to amplify the signal. As little as 0.01% methylated DNA (i.e. 2 pmol L−1) can be distinguished from the cocktail of methylated and unmethylated DNA by the proposed method. More importantly, this method shows good accuracy and sensitivity in profiling the methylation level of genomic DNA of three selected colonic cancer cell lines. This strategy provides a high throughput alternative with reasonable sensitivity and resolution for cancer study and diagnosis.

The mapping of specific single nucleotide polymorphisms (SNPs) in patients’ genome is a critical process for the development of personalized therapy. In this work, a DNA microarray-based resonance light scattering (RLS) assay has been developed for multiplexed detection of breast cancer related SNPs with high sensitivity and selectivity. After hybridization of the desired target single-stranded DNAs (ssDNAs) with the ssDNA probes on a microarray, the polyvalent ssDNA modified 13 nm gold nanoparticles (GNPs) are employed to label the hybridization reaction through the formation of a three-stranded DNA system. The H2O2-mediated enlargement of GNPs is then used to enhance the RLS signal. The microarray-based RLS assay provides a detection limit of 10 pM (S/N = 3) for the target ssDNA and determines an allele frequency as low as 1.0% in the target ssDNA cocktail. Combined with an asymmetric PCR technique, the proposed assay shows good accuracy and sensitivity in profiling 4 SNPs related to breast cancer of three selected cell lines.

In the present work, a portable and low-cost planar waveguide based resonance light scattering (RLS) scanner (termed as: PW-RLS scanner) has been developed for microarray detection. The PW-RLS scanner employs a 2 × 4 white light emitting diode array (WLEDA) as the excitation light source, a folded optical path with a complementary metal oxide semiconductor (CMOS) as the signal/image acquisition device and stepper motors with gear drives as the mechanical drive system. The biological binding/recognizing events on the microarray can be detected with an evanescent waveguide-directed illumination and light-scattering label (e.g., nanoparticles) while the microarray slide acts as an evanescent waveguide substrate. The performance of the as-developed PW-RLS scanner has been evaluated by analyzing type 2 diabetes mellitus (T2DM) risk genes. Highly selective and sensitive (less than 1% allele frequency at the attomole-level) T2DM risk gene detection is achieved using single-stranded DNA functionalized gold nanoparticles (ssDNA-GNPs) as detection probes. Additionally, the successful simultaneous analysis of 15 T2DM patient genotypes suggests that the device has great potential for the realization of a personalized diagnostic test for a given disease or patient follow-up.

Matrix metalloproteinases (MMPs) are believed to play an important role in tumor invasion. Herein, a peptide microarray-based fluorescence assay has been proposed for simultaneously determining the activities of MMP-2 and MMP-9 through the strong binding affinity of fluorescein isothiocyanate modified avidin (avidin-FITC) with the immobilized biotinylated peptide substrate on the microarray. In the presence of MMPs, the biotin moiety is released from the microarray by enzymatic cleavage of the peptide substrate, resulting in a significant decrease of the fluorescence signal. Under the optimal experimental conditions, the fluorescence intensity changes (ΔF%) are proportional to the concentrations of MMP-2 and MMP-9 within the ranges of 50 pg mL−1 to 50 ng mL−1 and 50 pg mL−1 to 100 ng mL−1 in the enzyme mixture, respectively. The detection limits are 45 pg mL−1 for MMP-2, and 60 pg mL−1 for MMP-9. In particular, the activities of extracellular MMP-2 and MMP-9 are determined by the peptide microarray-based fluorescence assay, and satisfactory results are obtained.

The multimodal molecular imaging technology, integrating the advantages of variant imaging methods, can provide more comprehensive and accurate information in cancer diagnosis, and realize timely personalized diagnosis of tumor at molecular and cellular level, quantitatively dynamic monitoring of tumor, etc. This review introduces the basic concepts of multimodal molecular imaging, implementation methods and recent research progress of the applications in tumor diagnosis. The development trend of multimodal molecular imaging in tumor diagnosis is also prospected.The basic molecular imaging modality applied in tumor diagnosis is introduced by analysis of the advantages and disadvantages of available imaging techniques. The implementation methods and application progress in tumor diagnosis are discussed by summarization of recently published literatures, and the development trend of multimodal molecular imaging is also prospected.

The phosphorylation of nucleic acid with 5′-OH termini catalyzed by polynucleotide kinase (PNK) involves several significant cellular events. Here a paper-based fluorescence assay with λ exonuclease assistance was reported for facile detection of PNK activity through monitoring the change of fluorescence intensity on paper surface. Cy5-labeled ssDNA was first immobilized on the surface of aldehyde group modified paper, and BHQ-labeled ssDNA was then employed to quench the fluorescence of the immobilized Cy5-labeled ssDNA with the help of an adaptor ssDNA. When PNK and λ exonuclease cleavage reaction were introduced, the fluorescence quenching effect on the paper surface was blocked because of the digestion of phosphorylated dsDNA by the coupled enzymes. By using this paper-based assay, PNK activity both in pure reaction buffer and in practical biosample have been successfully measured. Highly sensitive detection of PNK activity down to 0.0001 U mL–1 and lysate of about 50 cells is achieved. The inhibition of PNK activity has also been investigated and a satisfactory result is obtained.

Polydopamine nanoparticles (PDA NPs) which combine diagnostic and therapeutic functions are potentially useful in biomedicine. However, it is difficult to synthesize PDA NPs of a relatively small size (≤50 nm in diameter) using the traditional polymerization of dopamine monomers in an alkaline water–ethanol solution at room temperature. Herein, PDA NPs with average diameters ranging from 25 nm to 43 nm are prepared in a way which is similar to the silica-like reverse microemulsion process. The size of the PDA NPs can be modulated by changing the amount of dopamine monomers in the microemulsion. After conjugation with ferric ions (Fe3+), the poly(ethylene glycol) modified Fe–PDA NPs (termed as PEG–Fe–PDA NPs) exhibited pH-activatable magnetic resonance imaging (MRI) contrast and high photothermal performance. The combination of a small dimension and the pH-activatable MRI contrast can greatly facilitate tumor accumulation and increase the tumor imaging sensitivity against animal models in vivo. Completely inhibited tumor growth was achieved by the PEG–Fe–PDA NPs mediated by photothermal therapy with MRI guidance.

Carbon nanofibers (CNFs) have a wide range of applications and are commonly prepared under harsh conditions with small quantities. A green method for the preparation of CNFs under mild conditions with the scalable potential is highly challenging. Here, we describe a facile water-based room-temperature approach to producing gel fibers from a perylene diimide derivative via self-assembly, gelation, freeze-drying, and then to generating CNFs by subsequent pyrolysis under Ar. The entangled CNFs, with relatively uniform diameters around 20–50 nm, can be prepared as thin films or monoliths. The CNFs doped with elements N and Sn can be readily produced. The CNFs are characterized by various techniques and particularly evaluated as electrode materials for supercapacitor by cyclic voltammetry and galvanostatic charge-discharge. A non-ionic surfactant (Pluronics F-127) can be easily incorporated into the self-assembly process, which produces the CNFs with a higher surface area 520 m2 g−1 and a specific capacitance of 346 F g−1 at the scan rate of 1 mV s−1 or 192 F g−1 at the current density of 1 A g−1. The CNF electrodes are highly stable. Quite surprisingly, the specific capacitance increases with repeated testing, achieving an impressive 226 F g−1 for 1000 charge/discharge cycles at 4 A g−1.

Nanofibrous hydrogel microspheres are formed by pH gelation of perylene diimide derivatives in emulsion droplets. These microspheres are freeze-dried and subsequently carbonized to produce discrete N-doped nanofibrous carbon microspheres. The carbon microspheres show high performance as electrode materials for supercapacitors.

•Quantitatively study the inhibitors of Cu2+/Zn2+ induced β-amyloid aggregation.•The half maximal inhibitory concentrations (IC50) of inhibitors were obtained.•This method simplifies and reduces the cost of the inhibitors screening procedure.•This high throughput technology is helpful for anti-dementia drugs discovery.In this paper, a kind of gold nanoparticle (GNP)-based colorimetric assay has been developed for studying the reversible interaction of β-amyloid peptide (Aβ) with Cu2+ and Zn2+, and quantitatively analyzing four inhibitors (i.e., EDTA, EGTA, histidine and clioquinol) of Cu2+/Zn2+ induced Aβ assembly. The inhibition efficiencies (e.g., half maximal inhibitory concentration, IC50 value) of these inhibitors could be measured in this work. As far as we know, these IC50 values were reported at the first time. In this assay, the streptavidin conjugated GNPs (SA-GNPs) were employed as indicators to monitor the Cu2+/Zn2+ induced aggregating/disaggregating behaviors of biotin modified β-amyloid 1–16 peptides (Aβ1–16(biotin)). Because of high affinity of streptavidin (SA) with biotin, the aggregating/disaggregating of Aβ1–16(biotin) results in the significant color change of SA-GNPs. Furthermore, we demonstrate that the assay can be used as an effective tool for designing anti-dementia drugs through quantitative analysis of the interactions of four representative inhibitors with Cu2+/Zn2+ induced Aβ assembly.

It is important to develop methods to determine cylindrospermopsin (CYN) at trace levels since CYN is a kind of widespread cyanobacterial toxin in water sources. In this study, a label-free impedimetric aptasensor has been fabricated for detecting CYN. In this case, the amino-substituted aptamer of CYN was covalently grafted onto the surface of the thionine–graphene (TH–G) nanocomposite through the cross-linker glutaraldehyde (GA). The reaction of the aptamer with CYN was monitored by electrochemical impedance spectroscopy because the CYN induced conformation change of the aptamer can cause a remarkable decrease of the electron transfer resistance. Under optimum conditions, the aptasensor exhibits high sensitivity and a low detection limit for CYN determination. The CYN can be quantified in a wide range of 0.39 to 78 ng mL−1 with a good linearity (R2 = 0.9968) and a low detection limit of 0.117 ng mL−1. In addition, the proposed aptasensor displays excellent stability, reusability and reproducibility.

Herein, we present the synthesis and application of a new type of graphene-based magnetic and plasmonic nanocomposite for magnetic-field-assisted drug delivery and chemo-photothermal synergistic therapy. The nanocomposites were prepared via conjugation of the PEGylated Fe2O3@Au core/shell nanoparticles (Fe2O3@Au NPs) with reduced graphene oxide (rGO). The hybrid nanostructures (rGO–Fe2O3@Au NPs) are superparamagnetic and show great photothermal conversion efficiency under 808 nm near-infrared (NIR) laser irradiation and high drug loading ability (1.0 mg mg−1). MTT cell viability assay demonstrates that the chemotherapeutic drug, doxorubicin loaded rGO–Fe2O3@Au NPs (DOX–rGO–Fe2O3@Au NPs) have synergistic interaction between photothermal therapy (PTT) and chemotherapy. Furthermore, in vitro studies using HeLa cells show that the chemo-photothermal therapeutic efficacy of DOX–rGO–Fe2O3@Au NPs can be dramatically improved by the assistance of magnetic-field-guided drug delivery.

Taking advantage of the unique optical properties of upconversion nanoparticles (NP) and the feasibly modified nature of SiO2, NaYF4:Yb3+, Er3+@SiO2 core@shell (UCNP@SiO2) NPs with excellent morphology have been synthesized to investigate the surface charge effect on the interactions of NPs with cells. The cellular uptake behaviors, cytotoxicities and intracellular metal ion release of the as-prepared NPs have been investigated in two cell lines (HeLa and HepG-2) by fluorescence microscopy, MTT assay and inductively coupled plasma mass spectrometry (ICP-MS), respectively. It is found that the UCNP@SiO2 NPs with positive surface charge have much higher cell internalization ability and cytotoxicity than those with negative surface charge. The experimental results also demonstrate that the cytotoxicity of UCNP@SiO2 NP is closely related to the increase of intracellular reactive oxygen species (ROS) and metal ion release of internalized NPs.

In this work, spheres-on-sphere (SOS) silica microspheres are prepared via a facile one-pot synthesis. After functionalization with carboxyl groups, the carboxylated SOS silica microspheres (SOS-COOH microspheres) can serve as a support for horseradish peroxidase (HRP) covalent immobilization. The obtained enzyme hybrid (SOS-COOH-HRP) is more stable under alkaline conditions than the free counterpart, and exhibits longer-term storage stability and higher resistance toward the denaturing agents such as guanidine hydrochloride (GdmCl) and urea. The Michaelis–Menten constant (Km) of the immobilized enzyme is decreased slightly while the maximum rate of reaction (Vmax) is very close to that of free HRP, resulting in the catalytic efficiency of SOS-COOH-HRP being enhanced significantly. For evaluating its utility, a SOS-COOH-HRP-based colorimetric method has been developed for selectively and sensitively detecting H2O2 both in buffer and 10% diluted human serum. Furthermore, the SOS-COOH-HRP displays excellent reusability and reproducibility in cycle analysis. The results demonstrate that the SOS-COOH-HRP has great potential for practical applications in biosensing and industrial fields.

A peptide microarray-based fluorescent and resonance light scattering (RLS) two readout assay has been developed for screening thrombin inhibitors in blood samples. In this assay, the biotinylated peptide microarray was used as the reaction platform. The peptide C-terminal fragments carrying biotin sites departed from the slide when the biotinylated peptides were digested by thrombin hydrolysis reaction. The hydrolysis progress was labeled by fluorescent and 30-nm peptide-stabilized gold nanoparticles (GNPs) through the biotin-avidin interaction. In the presence of thrombin inhibitors, the hydrolysis reactions were blocked, and the inhibition capability of inhibitors could be detected by detecting fluorescent and RLS signal changes. The half maximal inhibitory concentration (IC50) of thrombin inhibitors in pure thrombin solution and spiked human serum was in order of argatroban < human antithrombin-III (HAT-III) < AEBSF. The absolute differences of IC50 between pure thrombin solution and spiked human serum increased with the decreasing inhibition specificity. The order of the inhibition activities of five compounds (7.5 μM) in human plasma was: argatroban > HAT-III > trypsin inhibitor > E-64 > AEBSF. The reversible or irreversible characters of argatroban and HAT-III have been estimated in human plasma. Compared with experimental data of fluorescent and RLS assay in blood sample, the RLS assay labeled by 30-nm GNPs is proven to be more suitable for the inhibitor detection in complex blood sample.A peptide microarray-based fluorescent and resonance light scattering two-readout assay has been developed for screening thrombin inhibitors in human plasma. Compared with fluorescent assay, the resonance light scattering method labeled by 30-nm gold nanoparticle probes is more suitable for inhibitor study in complex blood samples.

This work reports on a simple and feasible fluorescence resonance energy transfer (FRET) assay for detecting reactive oxygen species (ROS) both in solution and living cell using polydopamine nanoparticle (PDA NP) as energy acceptor and Cy5 labeled single-stranded DNA (Cy5-ssDNA) as energy donor. The Cy5-ssDNA and PDA NPs form self-assembled conjugates (Cy5-ssDNA-PDA NP conjugates) via π-stacking interactions. In the presence of ROS, the PDA NP adsorbed Cy5-ssDNAs can be effectively cleaved, resulting in the release of Cy5 molecules into solution and recovery of fluorescence emission of Cy5. In order to obtain ROS solution, the glucose oxidase-catalyzed oxidation reaction of glucose with O2 is employed to generate hydrogen peroxide for Fenton-like reaction. The formation of ROS in Fenton-like reaction can be detected as low as glucose oxidase-catalyzed oxidation of 100 pM glucose by the Cy5-ssDNA-PDA NP conjugate-based FRET assay. The recovery ratio of Cy5 fluorescence intensity is increased linearly with logarithm of glucose concentration from 100 pM to 1 μM, demonstrating that the FRET assay has wide dynamic range. In particular, intracellular ROS has been successfully detected in chemical stimulated HepG-2 cells by the Cy5-ssDNA-PDA NP conjugate-based FRET assay with a fluorescence microscopy, indicating that this approach has great potential to monitor ROS in living cells.

Multifunctional BaGdF5 nanospheres with mesoporous, luminescent, and magnetic properties have been successfully synthesized with the assistance of trisodium citrate by a hydrothermal method. The mesoporous structure is revealed by scanning electron microscope and transmission electron microscope images as well as N2 adsorption–desorption isotherm. The as-synthesized BaGdF5 nanospheres exhibit an intense broad bluish emission (centered at 450 nm) under the excitation of 390 nm, which might originate from the CO2·– radical-related defect produced by Cit3– groups. It is also shown that these BaGdF5 nanospheres brightened the T1-weighted images, suggesting that they could act as T1 contrast agents for magnetic resonance imaging. Using metformin hydrochloride as the model drug, the luminescent porous spheres show good drug storage/release capability. Furthermore, the emission intensity varies as a function of the cumulative drug release, making the drug-carrying system easily trackable and monitorable by detecting the luminescence intensity. Additionally, the paramagnetic property, originating from the unpaired electrons of Gd3+ ions, opens the possibility of directing the magnetic targeted carrier to the pathological site by magnetic field gradient.Keywords: BaGdF5; drug delivery; luminescence; magnetism; multifunctional material; porosity

A microarray-based resonance light scattering assay, with the combination of methylation-sensitive endonuclease and gold nanoparticle (GNP) probes, has been proposed to sensitively distinguish the DNA methylation level as low as 0.01% (10 pM methylated DNA in 100 nM total DNA) and detect human DNA methyltransferase 1 (Dnmt1) down to 0.1 U mL−1.

Herein, a gold nanoparticle (GNP)-based colorimetric aptasensor has been developed for detecting adenosine with exonuclease III (Exo III) assisted recycling amplification. In this aptasensor, two kinds of single-stranded oligonucleotide functionalized GNP probes (Oligo 1-GNPs and Oligo 2-GNPs) are firstly hybridized with one complementary single-stranded oligonucleotide (linker) with the motif of adenosine aptamer, resulting in the formation of GNP aggregates (cross-linked GNPs). In the presence of adenosine, the linker would form a double-stranded DNA (dsDNA) with a recessed 3′-terminus due to its structural switching property, which would lead to disassembly of the cross-linked GNPs. However, upon the addition of Exo III, the dsDNA is enzymatically digested from the 3′-hydroxyl termini, liberating the adenosine. The released adenosine can then interact with another linker and a new round of enzymatic digestion is started. Therefore, remarkable signal amplification is achieved because the disassembly of cross-linked GNPs is strongly dependent on the free adenosine in the reaction mixture. The experimental results demonstrate that the Exo III-assisted GNP-based colorimetric aptasensor is more sensitive (ca. 10 times) than that without Exo III amplification. The Exo III-assisted GNP-based colorimetric aptasensor detects adenosine downs to 5.6 nM, with a linear relationship from 10 nM to 1 mM. Moreover, the Exo III-assisted GNP-based colorimetric aptasensor has been successfully applied to detect Jinshuibao capsule (JSBC) containing adenosine in both a buffer solution and a diluted human serum, demonstrating that this assay has great potential to be employed for detecting adenosine in real samples.

In the present work, the chemical regulation of intracellular kinase activity has been studied by a peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle (AuNP) probes. After interactions of five cell lines and seven compounds (six potential inhibitors of cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) and Forskolin (Fsk)), we found that the intracellular PKA activity is strongly regulated by the extracellular compounds and that the compounds affect the intracellular PKA activity in a dose-dependent manner. The experimental results demonstrate that the peptide microarray-based RLS assay can be employed to quantitatively determine the efficiency of the inhibitor/activator on the kinase activity at the cellular level. In addition, chemical-mediated fluctuation of the PKA activity in different cell phases (e.g., G2/M phase and M/G1 phase) was successfully detected, which also demonstrates the utility of the approach for monitoring chemical regulation of intracellular kinase activity.

A gold nanoparticle (GNP)-based dynamic light scattering (DLS) assay has been developed for detecting mercury ion (Hg2+) in aqueous solution. The GNPs were able to maintain monodisperse state in relative high ionic strength (0.1 M NaCl) aqueous solution because Hg2+ aptamer 5′-TTTCTTCTTTCTTCCCCCCTTGTTTGTTGTTT-3′ (probe DNA) could adsorb on the GNP surface by electrostatic interaction. In the presence of Hg2+, the probe DNA molecules were easily desorbed from GNP surface because of T-Hg2+-T formation. The unprotected GNPs form aggregates in 100 mM NaCl solution, resulting in increased significantly the average hydrodynamic diameter of GNPs. Under the conditions of pH 7.43, 110 nM aptamer, 100 mM NaCl and 30 min incubation time of Hg2+ with aptamer, the difference of average hydrodynamic diameter (ΔD) of GNPs was increased linearly with logarithm of Hg2+ concentration over the range from 0.1 nM to 5 μM, with a detection limit of 0.1 nM. Moreover, satisfactory results were obtained when the proposed method was applied to detect Hg2+ in real samples.In the absence of the target, GNPs can maintain monodisperse state under the high ionic strength due to the absorption of the probe DNA could adsorb on GNP surface by electrostatic attraction. After reacted with Hg2+, the formation of T-Hg2+-T complex resulted in the DNA departing from GNPs surface. Under the high ionic strength, the unprotected GNPs form aggregates lead to an increase in hydrodynamic diameter of GNPs from D0 to D.

•Double-stranded DNA microarray-based RLS assay has been developed for studying restriction endonucleases′ functionalities and inhibitions.•Multiple restriction endonucleases were assayed simultaneously with good specificity and sensitivity.•Both substrate-binding and enzyme-binding inhibitors have been assayed qualitatively and quantitatively.Herein, a double-stranded (ds) DNA microarray-based resonance light scattering (RLS) assay with multifunctional gold nanoparticle (GNP) probes has been developed for studying restriction endonuclease functionality and inhibition. Because of decreasing significantly melting temperature, the enzyme-cleaved dsDNAs easily unwind to form single-stranded (ss) DNAs. The ssDNAs are hybridized with multiplex complementary ssDNAs functionalized GNP probes followed by silver enhancement and RLS detection. Three restriction endonucleases (EcoRI, BamHI and EcoRV) and three potential inhibitors (doxorubicin hydrochloride (DOX), ethidium bromide (EB) and an EcoRI-derived helical peptide (α4)) were selected to demonstrate capability of the assay. Enzyme activities of restriction endonucleases are detected simultaneously with high specificity down to the limits of 2.0×10−2 U/mL for EcoRI, 1.1×10−2 U/mL for BamHI and 1.6×10−2 U/mL for EcoRV, respectively. More importantly, the inhibitory potencies of three inhibitors are showed quantitatively, indicating that our approach has great promise for high-throughput screening of restriction endonuclease inhibitors.

•The 3D carbohydrate microarray has been fabricated on glutaraldehyde activated polyacrylamide hydrogel spots.•The immobilized monosaccharides have high binding affinities with lectins.•The 3D carbohydrate hydrogel microarray has high efficiency for capturing bacterium.•Bacterial adhesion inhibition assay has been successfully carried out by the 3D carbohydrate hydrogel microarray.Herein, a three-dimensional carbohydrate modified polyacrylamide hydrogel microarray (3D carbohydrate hydrogel microarray) has been fabricated and employed as micro-reactor for capturing Escherichia coli (E. coli) by multivalent binding of concanavalin A (Con A) with O-antigen on the cellular surface of E. coli and immobilized monosaccharides on hydrogel spot, and the interactions of type 1 fimbriae of E. coli with immobilized monosaccharides. Because of the transparent performance of polyacrylamide hydrogel, the captured E. coli can be directly observed by a conventional microscope under a bright-field mode. The experimental result demonstrates that α-D-mannopyranoside (Man-α) modified hydrogel surface shows high efficiency of E. coli capturing. The 3D Man-α hydrogel microarray-based assay shows reasonable low detection limit (1.0×104 cells/mL) and large dynamic range (1.0×105 to 1.0×109cells/mL) for detecting E. coli. In addition, bacterial adhesion inhibition assay has been demonstrated by the interactions of E. coli with ten saccharides, and satisfactory results have been obtained.

A peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle probes has been developed for monitoring thrombin generation in human plasma. Thrombophilia, hypocoagulability and normal plasma have been successfully differentiated by the assay.

An optical waveguide resonance light-scattering scanner (RLS Scanner) was developed for microarray detection. The major components of the device included optical system, waveguide excitation system, photovoltaic conversion system, mechanical drive system and PC software. The minimum scanning resolution of the RLS scanner was 5 µm, and the maximum scanning range was 100 mm. The signal-to-noise ratio (SNR) of RLS was improved by the waveguide excitation mode. This device is capable of using a white light source as excitation source, thereby providing significant cost-savings. Several kinds of microarrays including carbohydrate microarray, DNA microarray and peptide microarray with gold nanoparticle (GNP) probes were used to demonstrate the detection performance of the device. Detection limits of 1 ng mL−1 and 100 pM in solution were obtained for concanavalin A (Con A) and DNA respectively. For the peptide on microarray spots, a detection limit of 100 fg was reported. The RLS scanner showed at least one to two orders of magnitude more sensitive than that of commercial scanner. Furthermore, taking advantage of the RLS technique, the device was characterized by simple construction and low cost.An optical waveguide resonance light-scattering scanner has been developed for microarray detection. In comparison with commercial scanner with surface excitation mode, this device has better detection performance (high signal intensity and low background noise) and reasonably lower detection limits for Con A and DNA in solutions and immobilized peptide on microarray spots.

•A simple way of preparing GO–AgNPs nanohybrids based on electrostatic interactions was developed.•Different densities, sizes and shapes of AgNPs have been conjugated to GO sheets easily.•AgNPs anchored on GO sheets showed better stability than that of colloidal AgNPs.•GO–AgNPs exhibited enhanced antibacterial activities towards both G+ and G− bacterial strains than that of AgNPs.A simple method based on electrostatic interactions was utilized to assemble silver nanoparticles (AgNPs) to graphene oxide (GO) sheets. This method allows conjugation of AgNPs with desired morphologies (densities, sizes and shapes) onto GO. In this process, poly(diallyldimethylammonium chloride) (PDDA) was introduced as an adhesive agent. The as-prepared graphene oxide–AgNPs composites (GO–AgNPs) have enhanced colloid stability and photo-stability than that of AgNPs. After conjugating to GO sheets, the antibacterial activities of AgNPs against Gram negative (G−) bacterial strain (Escherichia coli, E. coli) and Gram positive (G+) bacterial strain (Bacillus subtilis, B. subtilis) have been improved significantly. The antibacterial activity of GO–AgNPs is dependent on the size of AgNPs, i.e. the small AgNPs modified GO sheets show more effective antibacterial capability than that of large AgNPs modified GO sheets. Compared with AgNPs, the enhanced antibacterial activity of GO–AgNPs might not only be due to high stability of AgNPs anchored on GO sheets, but also the positive charged surface of hybrids which increases the electrostatic interaction of bacterial cell membrane with nanohybrids.

•A conducting hydrogel-based electrochemical sensor was developed for rapid detection of copper (II) ions.•High selective recognition of copper (II) ions down to 1 nmol L−1 is demonstrated.•The polyacrylamide-phytic acid-polydopamine conducting hydrogel was synthesized for the first time.•The conducting hydrogel presents a great removal capacity toward copper (II) ions.In this work, a conducting porous polymer hydrogel-based electrochemical sensor has been developed for rapid detection of copper (II) ions (Cu2+). The polymer (termed as PAAM/PA/PDA) hydrogel is prepared through multi-interactions of the monomers dopamine (DA), acrylamide (AAM) and phytic acid (PA) under mild ambient conditions: the AAM polymerizes through free-radical polymerization, DA occurs poly coupling reaction, and PA crosslinks polydopamine (PDA) and polyacrylamide (PAAM) by hydrogen bonds. The three dimensional (3D) network nanostructured PAAM/PA/PDA hydrogel not only provides a large surface area for increasing the amount of immobilized molecules/ions, but also exhibits a good conductivity. The PAAM/PA/PDA hydrogel-based electrochemical sensor exhibits a low detection limit (1 nmol L−1, S/N=3) and wide linear range (from 1 nmol L−1 to 1 µmol L−1) for Cu2+ detection in aqueous samples. Furthermore, the Cu2+ can be sensitively detected by the electrochemical sensor in different sample matrices, indicating that the electrochemical sensor could be used to monitor Cu2+ with reasonable assay performance in practical samples. The PAAM/PA/PDA hydrogel also exhibits a good capacity to remove Cu2+(231.36±4.70 mg g−1), which is superior to those of other adsorption materials reported in the literature. The facile synthesized PAAM/PA/PDA hydrogel provides a novel and regenerable platform for monitoring and removing Cu2+ in real samples.

Herein, a gold nanoparticle (GNP)-based colorimetric aptasensor has been developed for detecting adenosine with exonuclease III (Exo III) assisted recycling amplification. In this aptasensor, two kinds of single-stranded oligonucleotide functionalized GNP probes (Oligo 1-GNPs and Oligo 2-GNPs) are firstly hybridized with one complementary single-stranded oligonucleotide (linker) with the motif of adenosine aptamer, resulting in the formation of GNP aggregates (cross-linked GNPs). In the presence of adenosine, the linker would form a double-stranded DNA (dsDNA) with a recessed 3′-terminus due to its structural switching property, which would lead to disassembly of the cross-linked GNPs. However, upon the addition of Exo III, the dsDNA is enzymatically digested from the 3′-hydroxyl termini, liberating the adenosine. The released adenosine can then interact with another linker and a new round of enzymatic digestion is started. Therefore, remarkable signal amplification is achieved because the disassembly of cross-linked GNPs is strongly dependent on the free adenosine in the reaction mixture. The experimental results demonstrate that the Exo III-assisted GNP-based colorimetric aptasensor is more sensitive (ca. 10 times) than that without Exo III amplification. The Exo III-assisted GNP-based colorimetric aptasensor detects adenosine downs to 5.6 nM, with a linear relationship from 10 nM to 1 mM. Moreover, the Exo III-assisted GNP-based colorimetric aptasensor has been successfully applied to detect Jinshuibao capsule (JSBC) containing adenosine in both a buffer solution and a diluted human serum, demonstrating that this assay has great potential to be employed for detecting adenosine in real samples.

In the present work, the chemical regulation of intracellular kinase activity has been studied by a peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle (AuNP) probes. After interactions of five cell lines and seven compounds (six potential inhibitors of cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) and Forskolin (Fsk)), we found that the intracellular PKA activity is strongly regulated by the extracellular compounds and that the compounds affect the intracellular PKA activity in a dose-dependent manner. The experimental results demonstrate that the peptide microarray-based RLS assay can be employed to quantitatively determine the efficiency of the inhibitor/activator on the kinase activity at the cellular level. In addition, chemical-mediated fluctuation of the PKA activity in different cell phases (e.g., G2/M phase and M/G1 phase) was successfully detected, which also demonstrates the utility of the approach for monitoring chemical regulation of intracellular kinase activity.

A peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle probes has been developed for monitoring thrombin generation in human plasma. Thrombophilia, hypocoagulability and normal plasma have been successfully differentiated by the assay.

Nanofibrous hydrogel microspheres are formed by pH gelation of perylene diimide derivatives in emulsion droplets. These microspheres are freeze-dried and subsequently carbonized to produce discrete N-doped nanofibrous carbon microspheres. The carbon microspheres show high performance as electrode materials for supercapacitors.

Carbon nanofibers (CNFs) have a wide range of applications and are commonly prepared under harsh conditions with small quantities. A green method for the preparation of CNFs under mild conditions with the scalable potential is highly challenging. Here, we describe a facile water-based room-temperature approach to producing gel fibers from a perylene diimide derivative via self-assembly, gelation, freeze-drying, and then to generating CNFs by subsequent pyrolysis under Ar. The entangled CNFs, with relatively uniform diameters around 20–50 nm, can be prepared as thin films or monoliths. The CNFs doped with elements N and Sn can be readily produced. The CNFs are characterized by various techniques and particularly evaluated as electrode materials for supercapacitor by cyclic voltammetry and galvanostatic charge-discharge. A non-ionic surfactant (Pluronics F-127) can be easily incorporated into the self-assembly process, which produces the CNFs with a higher surface area 520 m2 g−1 and a specific capacitance of 346 F g−1 at the scan rate of 1 mV s−1 or 192 F g−1 at the current density of 1 A g−1. The CNF electrodes are highly stable. Quite surprisingly, the specific capacitance increases with repeated testing, achieving an impressive 226 F g−1 for 1000 charge/discharge cycles at 4 A g−1.

Polydopamine nanoparticles (PDA NPs) which combine diagnostic and therapeutic functions are potentially useful in biomedicine. However, it is difficult to synthesize PDA NPs of a relatively small size (≤50 nm in diameter) using the traditional polymerization of dopamine monomers in an alkaline water–ethanol solution at room temperature. Herein, PDA NPs with average diameters ranging from 25 nm to 43 nm are prepared in a way which is similar to the silica-like reverse microemulsion process. The size of the PDA NPs can be modulated by changing the amount of dopamine monomers in the microemulsion. After conjugation with ferric ions (Fe3+), the poly(ethylene glycol) modified Fe–PDA NPs (termed as PEG–Fe–PDA NPs) exhibited pH-activatable magnetic resonance imaging (MRI) contrast and high photothermal performance. The combination of a small dimension and the pH-activatable MRI contrast can greatly facilitate tumor accumulation and increase the tumor imaging sensitivity against animal models in vivo. Completely inhibited tumor growth was achieved by the PEG–Fe–PDA NPs mediated by photothermal therapy with MRI guidance.