Light-Controlled Regulation of Dual-Enzyme Properties in YbGd-Carbon Quantum Dots Nano-Hybrid for Advanced Biosensing.

Compared to nanozymes with single enzyme activity, those with multiple enzyme activities possess broader application potential due to their diversified enzymatic functionalities. However, the multienzyme nanozymes currently face challenges of interference among different enzymatic activities during practical applications. In this study, we report the synthesis of a light-responsive YbGd-carbon quantum dots nano-hybrid, termed YbGd-CDs, which exhibits controllable enzyme-mimicking activities. This light-responsive behavior enables selective control of the enzymatic activities. Under visible light irradiation, YbGd-CDs demonstrate robust oxidase-like activity. Conversely, under dark conditions, they primarily exhibit peroxidase-like activity. Leveraging the dual-enzyme-mimicking capabilities of YbGd-CDs, we developed colorimetric assays for sensitive detection of total antioxidant capacity (TAC) in both normal and cancer cells as well as d-amino acids in human saliva. This study not only advances the synthesis of carbon-based nanozymes but also highlights their potential in biosensing applications.

Entropy-Driven Catalytic G-Quadruple Cycle Amplification Integrated with Ligases for Label-Free Detection of Single Nucleotide Polymorphisms.

G-Quadruplex/thioflavin (G4/THT) has become a very promising label-free fluorescent luminescent element for nucleic acid detection due to its good programmability and compatibility. However, the weak fluorescence efficiency of single-molecule G4/THT limits its potential applications. Here, we developed an entropy-driven catalytic (EDC) G4 (EDC-G4) cycle amplification technology as a universal label-free signal amplification and output system by properly programming classical EDC and G4 backbone sequences, preintegrated ligase chain reaction (LCR) for label-free sensitive detection of single nucleotide polymorphisms (SNPs). First, the positive strand LCR enabled specific transduction and preliminary signal amplification from single-base mutation information to single-strand information. Subsequently, the EDC-G4 cycle amplification reaction was activated, accompanied by the production of a large number of G4/THT luminophores to output fluorescent signals. The EDC-G4 system was proposed to address the weak fluorescence of G4/THT and obtain a label-free fluorescence signal amplification. The dual-signal amplification effect enabled the LCR-EDC-G4 detection system to accurately detect mutant target (MT) at concentrations as low as 22.39 fM and specifically identify 0.01% MT in a mixed detection pool. Moreover, the LCR-EDC-G4 system was further demonstrated for its potential application in real biological samples. Therefore, this study not only contributes ideas for the development of label-free fluorescent biosensing strategies but also provides a high-performance and practical SNP detection tool in parallel.

Gut-Derived Trimethylamine N-Oxide Promotes CCR2-Mediated Macrophage Infiltration in acute kidney injury.

BACKGROUND: Inflammation is crucial in the development of AKI and subsequent CKD following renal ischemia-reperfusion (IR) injury. Gut microbiota metabolites trigger inflammation and affect IR-induced renal damage. Yet, the driving factors and mechanisms are unclear. Trimethylamine N-oxide (TMAO), a gut-derived choline metabolite, is a strong pro-inflammatory factor that increases in patients with AKI and CKD. We hypothesized that TMAO can promote renal injury caused by IR. METHODS: Mice subjected to unilateral renal IR to induce AKI and CKD were fed a high-choline diet to observe the effects of TMAO on kidney inflammation, fibrosis, and macrophage dynamics. RESULTS: A choline-rich diet altered the gut microbiota and elevated TMAO levels, which exacerbated IR-induced AKI and subsequent CKD. Single-cell analysis identified a distinct subset of CCR2+ macrophages derived from monocytes as key responders to TMAO, intensifying immune cell interactions and worsening renal injury. TMAO promoted sustained CCR2 expression after IR, increasing macrophage infiltration. CCR2 deletion and antagonist RS-102895 improved TMAO-induced inflammation and fibrosis, alleviated renal injury induced by IR. CONCLUSIONS: Our study provides valuable insights into the link between TMAO and IR-incited renal inflammation and fibrosis, emphasizing the critical role of TMAO-mediated macrophage infiltration via CCR2 as a key therapeutic target in the acute and chronic phase after IR.

A renewable screen-printed electrode based on magnetic NiCo@N-doped carbon nanotubes derived from Co-MOF for ractopamine detection.

A renewable electrochemical screen-printed electrode (SPE) is proposed based on magnetic bamboo-like nitrogen-carbon (N-C) nanotubes loaded with nickel-cobalt alloy (NiCo) nanoparticles (NiCo@N-CNTs) for the determination of ractopamine (RAC). During the preparation of NiCo@N-CNTs, Co-MOF-67 (ZIF-67) was firstly synthesized, and then blended with dicyandiamide and nickel acetate, followed by a one-step pyrolysis procedure to prepare NiCo@N-doped carbon nanotubes. The surface morphology, structure, and chemical composition of NiCo@N-CNTs were characterized by SEM, TEM, XRD, XPS, and EDS. The electrocatalytic and electrochemical behavior of NiCo@N-CNTs were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that NiCo@N-CNTs possessed remarkable conductivity and electrocatalysis to the oxidation of ractopamine (RAC). By using screen-printed electrode (SPE), NiCo@N-CNTs, and a designed base support, a magnetic RAC sensor (NiCo@N-CNTs/SPE) was successfully constructed. It presented a detection linear range of 0.05-80 µM with a detection limit of 12 nM (S/N = 3). It also exhibited good sensitivity, reproducibility, and practicability in spiked real pork samples. Since the adhesion of NiCo/N-CNTs on SPE was controlled by magnet, the NiCo@N-CNTs was easily detached from the SPE surface by magnetism and thus displayed excellent renewability. This work broadened insights into portable devices for on-site and real-time analysis.

A dual-mode strategy based on ß-galactosidase and target-induced DNA polymerase protection for transcription factor detection using colorimetry and a glucose meter.

In this work, we report a novel dual-mode method for the highly specific and sensitive detection of transcription factors (TFs) via the integration of Klenow polymerase protection induced by target-specific recognition, cascade-signal amplification using the hybridization chain reaction (HCR) and CRISPR/Cas12a system, and dual-signal transduction mediated by ß-galactosidase (ß-gal) and two substrates. A dual-mode signal-sensing interface was constructed by immobilizing the oligo DNA probe (P1) tethered ß-gal in a 96-well plate. A hairpin H1 with the ability to initiate HCRs was designed to contain the TF binding site. The binding between the TF and H1 protected the H1 from being extended by the Klenow fragment. After thermal denaturation, the reserved H1 launched the HCR and the HCR products activated CRISPR/Cas12a to cleave P1 and reduce the ß-gal on the sensing interface, and thus the contents of the TFs and the corresponding signals mediated by the catalysis of ß-gal showed a correlation. This work was the first attempt at utilizing ß-gal for dual-signal transduction. It is a pioneering study to utilize the HCR-CRISPR/Cas12a system for dual-mode TF sensors. It revealed that DNA polymerase protection through the binding of TF and DNA could be applied as a new pattern to develop TF sensors.

Anti-phospholipase A2 receptor antibody levels at diagnosis predicts outcome of TAC-based treatment for idiopathic membranous nephropathy patients.

BACKGROUND: Idiopathic membranous nephropathy (iMN) is recognized as an organ-specific autoimmune disease, mainly caused by anti-PLA2R antibody. This study aimed to study between anti-PLA2R antibody level at diagnosis and the response to tacrolimus (TAC)-based treatment in iMN patients. METHODS: This was a retrospective cohort study including 94 kidney biopsy-proven MN patients with positive anti-PLA2R antibody at diagnosis from May 2017 to September 2021 in our center. All iMN patients received the TAC regimen as the initial immunosuppressive therapy. All patients were divided into two groups according to anti-PLA2R antibody titer at diagnosis: high-level group (> 150 RU/ml; n = 42) and low-level group (≤ 150 RU/ml; n = 52). The association between anti-PLA2R antibody levels and clinical outcomes was assessed using the Kaplan-Meier method. RESULTS: The low density lipoprotein in the high-level group was significantly higher than low-level group at diagnosis, otherwise, serum albumin was significantly lower than low-level group; however, there was no significant difference in creatinine levels between two groups. The remission rates were significantly higher in the low-level group than high-level group after treatment with TAC for 12, 18, or 24 months (all P < 0.05). After 12 months of treatment with TAC, 82.7% of the patients in the low-level group achieved complete remission (CR) or partial remission (PR) (mean, 6.52 ± 0.53 months). However, 38.1% of the patients in high-level group achieved CR or PR (mean, 9.86 ± 0.51 months). Moreover, CR rate at 12 months in the high-level group was only 4.7% (mean, 11.88 ± 0.63 months). The infection frequency in the high-level group (35.6%) was higher than the low-level group (20%) during the TAC treatment, although there was no significant difference (P = 0.065). There were 19% patients who had end-stage kidney disease (ESKD), and 7.1% of patients died of ESKD in the high-level group during the follow-up period. CONCLUSION: Anti-PLA2R antibody level above 150 RU/ml at diagnosis can predict a poor treatment response and outcome of TAC treatment in iMN patients, who may not benefit from TAC or other calcineurin inhibitor regimens as the initial treatment.

Dual-mode photoelectrochemical/electrochemical sensor based on Z-scheme AgBr/AgI-Ag-CNTs and aptamer structure switch for the determination of kanamycin.

A "signal-on" dual-mode aptasensor based on photoelectrochemical (PEC) and electrochemical (EC) signals was established for kanamycin (Kana) assay by using a novel Z-scheme AgBr/AgI-Ag-CNTs composite as sensing platform, an aptamer structure switch, and K3[Fe(CN)6] as photoelectron acceptor and electrochemical signal indicator. The aptamer structure switch was designed to obtain a "signal-off" state, which included an extended Kana aptamer (APT), one immobilized probe (P1), and one blocking probe (P2) covalently linked with graphdiyne oxide (GDYO) nanosheets. P1, P2, and aptamer formed the double helix structure, which resulted in the inhibited photocurrent intensity because of the weak conductivity of double helix layer and serious electrostatic repulsion of GDYO towards K3[Fe(CN)6]. In the presence of Kana, APT specifically bound to the target and dissociated from P1 and P2, and thus, a "signal-on" state was initiated by releasing P2-GDYO from the platform. Based on the sensing platform and the aptamer structure switch, the dual-mode aptasensor realized the linear determination ranges of 1.0 pM-2.0 µM with a detection limit (LOD) of 0.4 pM (for PEC method) and 10 pM-5.0 µM with a LOD of 5 pM (for EC method). The aptasensor displayed good application potential for Kana test in real samples.

Changes in the spectrum of kidney diseases: a survey of 2803 patients from 2010 to 2018 at a single center in southeastern China.

Primary glomerular disease was the leading cause of chronic kidney disease (CKD) in China; however, changes in the economy and environment introduce variations in the spectrum of kidney diseases. This study aimed to analyze renal biopsy data to inform disease prevention and public health interventions. In this retrospective cohort study, data from 2,803 consecutive renal biopsies conducted at our center between January 2010 and December 2018 were analyzed. The sample was disaggregated by age and the date of biopsy to facilitate analysis. Primary glomerulonephritis (PGN) is the most frequent (81.84%) finding, followed by secondary glomerulonephritis (SGN; 15.38%), tubulointerstitial nephritis (15.38%), and others (1.57%). IgA nephropathy (IgAN), idiopathic membranous nephropathy (iMN), and minimal change disease were the primary causes of PGN. Among PGN cases, the incidence of iMN arose, especially among those aged ≥ 60 years old, during the observation period. Contrary to the case of iMN, the proportion of IgAN in PGN trended downward, continuously, and at length. Moreover, IgAN mainly affected those aged 25-44 years old and less so those aged ≥ 60 years old. Lupus nephritis, Henoch-Schönlein purpura nephritis, and diabetic nephropathy (DN) were key causes of SGN. A ratio reversal between infectious disease and chronic disease dramatically changed SGN patterns. In the past year, the incidence of hepatitis B-related nephritis has constantly declined; however, the proportion of DN among SGN had steadily increased. The incidence of iMN significantly increased during these years. Among SGN cases, the proportion of DN has increased.

Visual Quantitative Detection of Glutathione and Cholesterol in Human Blood Based on the Thiol-Ene Click Reaction-Triggered Wettability Change of the Interface.

Herein, we proposed an innovative visual quantitative sensing strategy based on thiol-ene click chemistry and the capillary action principle. A triethoxyvinylsilane (VTEO)- or mercaptopropylsilatrane (MPS)-modified interface was prepared for analyte recognition. Target analyte molecules containing thiol groups or C═C double bonds are coupled to the VTEO- or MPS-modified inner surface of the glass capillary tube via a thiol-ene click reaction, respectively. Then, the molecular recognition events were transformed into the wettability change of the inner wall of the glass capillary. The concentration of the target molecules was quantified by reading the height change of the water column in the capillary tube. As a proof of concept, this strategy was successfully used to build visual quantitative sensors for detecting glutathione and cholesterol. In addition, this strategy showed a good anti-interference ability to complex biological fluids and realized sensitive glutathione (GSH) and cholesterol detection in real human blood samples.

De Novo Development of a Universal Biosensing Platform by Rapid Direct Native Protein Modification.

An innovative biosensing assay was developed for simplified, cost-effective, and sensitive detection. By rapid, direct treatment of target proteins with iron porphyrin (TPPFe) in situ, a carboxyl group of amino acid conjugates with an Fe atom of the TPPFe molecule, forming a stable protein complex. We have shown that this complex not only maintains the integrity and functions of original proteins but also acquires peroxidase activity that can turn TMB to a comparably visible signal like that in ELISA. This study is unique since such conversion is difficult to achieve with standard chemical modification or molecular biology methods. In addition, the proposed immunoassay is superior to traditional ELISA as it eliminates an expensive and complicated cross-linking process of an enzyme-labeled antibody. From a practical point of view, we extended this assay to rapid detection of clinically relevant proteins and glucose in blood samples. The results show that this simple immunoassay provides clinical diagnosis, food safety, and environmental monitoring in an easy-to-implement manner.

Tunable graphdiyne for DNA surface adsorption: affinities, displacement, and applications for fluorescence sensing.

Graphdiyne (GDY) adsorbed DNA probes have been used as a fluorescent sensing platform, but topics including DNA adsorption affinities, DNA probe displacement, and fluorescence quenching ability were rarely researched. Herein, the adsorption affinity of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) on a tremella-like GDY was tuned by modulating the surface chemistry of GDY. The fluorescence quenching ability of GDY with different oxidation degrees was compared. The nonspecific displacement of DNA probes on GDY was studied. Under the same concentrations, GDY with low oxidation degree exhibited stronger adsorption affinity and higher adsorption capacity to both ssDNA and dsDNA than highly oxidized GDY. DNA adsorbed on low-oxidized GDY was more resistant to displacement by other DNAs. Protein showed strong interaction with different GDY and could displace DNA probes on GDY. Based on these findings, an ideal GDY with proper oxidation degree, exhibiting high surface affinity for ssDNA and low affinity for dsDNA, was used as scavenger of redundant ssDNA fluorescent probe in an enzyme-assisted amplification system for sensitive ochratoxin (OTA) detection. This study has enhanced our fundamental understanding of DNA adsorption by GDY. It also provided a rational way to apply GDY for fluorescence sensing in a complicated system.

Real-Time Imaging Redox Status in Biothiols and Ferric Metabolism of Cancer Cells in Ferroptosis Based on Switched Fluorescence Response of Gold Carbon Dots.

Ferroptosis is an iron-dependent form of regulated cell death. In this study, a ratiometric fluorescent probe, gold carbon dots (GCDs) consisting of carbon skeleton and gold nanoclusters, was used for in situ imaging to monitor redox status in biothiols (glutathione and cysteine) and ferric metabolism of cancer cells in ferroptosis. The as-prepared GCDs can selectively respond to biothiols, interestingly, the fluorescence may be switched to sense ferric ions without interference by biothiols under proper conditions. The robust GCDs-probe exhibits excellent photobleaching resistance and can reversibly respond to intracellular biothiols/ferric ion with high temporal resolution. The 8 h real-time imaging of living cells was employed to track the fluctuation of biothiols, showing the change of redox status in ferroptosis. In addition, release of ferric ions in cells was monitored. The real-time imaging of depletion of biothiols and release of ferric ion in cells indicates the GCDs-probe can monitor how the ferroptosis regulates redox status in biothiols and ferric metabolism.

Single Primer Based Multisite Strand Displacement Reaction Amplification Strategy for Rapid Detection of Terminal Deoxynucleotidyl Transferase Activity.

A fluorescence-based multisite strand displacement reaction (MSSDR) amplification strategy is developed for the rapid, sensitive, and selective detection the activity of terminal deoxynucleotidyl transferase (TdT). Oligo dT primer was used for the TdT extension reaction, then the left oligo dT primers were hybridized to the TdT extension reaction product by end to end tiled style and initiated the MSSDR by Klenow polymerase, subsequently, 3' terminals of these single-strand DNA produced by MSSDR are folded back to complement themselves with the adjacent sequences, and Klenow polymerase makes it into double-stranded DNA (dsDNA). The final dsDNA products were analyzed via dsDNA specific fluorescent dye. This method enables rapid (less than 100 min) and sensitive (limit of detection, LOD, 1.35 × 10-5 U) detection and has been demonstrated to work well using a real biosample. Our design would not only serve as a new prototype for high-throughput automated analysis and clinic diagnostic application but also has promising potential for improving the sensitivity of those TDT related biosensing system.

Novel long non-coding RNA AV310809 promotes TGF-ß1 induced epithelial-mesenchymal transition of human peritoneal mesothelial cells via activation of the Wnt2/ß-catenin signaling pathway.

Peritoneal fibrosis (PF) is a crucial cause of the loss of peritoneal function in patients with peritoneal dialysis. To better understand the underlying mechanism of PF, we selected AV310809, which is one of the most highly upregulated lncRNA in fibrotic peritoneal tissue, for functional analysis. We used co-expression analysis to explore the potential relationship between AV310809 and coding genes. qPCR, WB and IF were applied to evaluate the expression and localization of AV310809, epithelial markers and proteins involved in the Wnt2/ß-catenin signaling pathway. The interaction between AV310809 and ß-catenin was examined using an RNA pulldown assay. The expression level of AV310809 was upregulated in fibrotic peritoneum and TGF-ß1 induced EMT in HPMCs. Ectopic overexpression of AV310809 promoted EMT and activated the Wnt2/ß-catenin signaling pathway. Furthermore, we demonstrated that AV310809 could interact with ß-catenin and blocking ß-catenin inhibited the augmentation of EMT by AV310809. These findings indicated that AV310809 promoted TGF-ß1-induced EMT in HPMCs through the activation of the Wnt2/ß-catenin signaling pathway, possibly by targeting ß-catenin. We suggest that AV310809 may be a new therapeutic target for the management of peritoneal dialysis-associated PF.

Aptamer based ratiometric electrochemical sensing of 17ß-estradiol using an electrode modified with gold nanoparticles, thionine, and multiwalled carbon nanotubes.

Gold nanoparticles (AuNPs) with a size of ~3 nm were placed on a thionine-multiwalled carbon nanotube (Thi-CNTs) conjugate to form a novel AuNP-Thi-CNTs nanocomposite. Its morphology and composition were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The nanocomposite was placed on an electrode and used as a redox-active signaling interface to fabricate a ratiometric electrochemical aptasensor for 17ß-estradiol (E2). The potentiostatic insertion method was applied to insert an aptamer against E2 into a thin alkane monolayer to warrant an adequate distance between aptamers. The aptamer against E2 acts as both a collector and separator to specifically bind E2. The electrode displays two peak signals (at +0.50 V vs. SCE for E2; and at -0.32 V for Thi) which increase and decrease, respectively, in the 12 pM to 60 nM E2 concentration range. Therefore, the current ratio can be used to reliably, reproducibly, and sensitively quantify the concentration of E2. Graphical abstract Schematic presentation of a novel AuNP-Thi-CNTs nanocomposite. AuNP-Thi-CNTs showed good electrocatalytic oxidation to E2. AuNP-Thi-CNTs was used as self-redox signal interface to fabricate aptasensor. Dual signals of extrinsic E2 and inner Thi was applied to monitor the concentration of E2.

Prompting peroxidase-like activity of gold nanorod composites by localized surface plasmon resonance for fast colorimetric detection of prostate specific antigen.

The interaction between incident light and surface electrons in conductive nanoparticles produces localized plasmon oscillations with a resonant frequency that strongly depends on the composition, size, geometry, and dielectric environment. Hybrid heterostructure materials combining two or more materials in one structure represent a powerful way to achieve unique properties and multifunctionality compared to those of the individual nanoparticle components. Hybrid gold nanorods and gold nanoclusters (GNR/AuNCs) heterostructures prepared by intimate integration of GNRs with AuNCs exhibit both localized surface plasmon resonance (LSPR) property and peroxidase-like activity. It is found that the catalytic activity of the AuNC/GNR heterostructure could be remarkably enhanced by LSPR induced by photon-plasmon coupling in the visible to near-infrared (NIR) region. Meanwhile, the catalytic activity of enzyme-like AuNC/GNRs may be regulated by immunoreactions to realize specific recognition of a target analyte. Accordingly, a fast colorimetric assay within 5 min for the detection of prostate specific antigen (PSA) was developed based on a AuNC/GNRs heterostructure mask regulated by the target molecule under photon-plasmon coupling. The color intensity is inversely proportional to the PSA concentration, and quantitative analysis may be achieved in a range of 10 and 200 pg mL-1. This sensor was practically applied to detect PSA levels in prostate cancer serum samples and the determined values agreed well with those measured by the hospital using standard methods. This indicates that the AuNC/GNRs heterostructure-based assay has high accuracy for the analysis of practical samples. Moreover, the new method has the advantages of very fast determination and low sample volume requirements.

Peroxidase-Like Activity of Ethylene Diamine Tetraacetic Acid and Its Application for Ultrasensitive Detection of Tumor Biomarkers and Circular Tumor Cells.

Ethylene diamine tetraacetic acid (EDTA) is such a powerful chelating agent that it may form stable complexes with most metal ions, which has wide applications in industry, agriculture, environment, and pharmaceutical technology. Recently, EDTA was found to enhance the photocatalytic property of some materials. Inspired by this fact of EDTA in the photocatalytic role, we further investigated the photocatalytic property of EDTA and found much the same as that of natural horseradish peroxidase (HRP). This significant discovery of peroxidase-like property may extend the applications of conventional EDTA in life science. A novel and colorimetric sensor based on the peroxidase-like EDTA and unique gold nanorods (GNRs) was designed. Under light irradiation, EDTA may catalyze decomposition of hydrogen peroxide and in situ regulate the longitudinal plasmon wavelength (LPW) of GNRs, displaying various color solution as a read-out means. This colorimetric nanosensor has a great potential to develop into a platform to quantitatively determine analytes as long as the specific antibodies against them were available. Biomarkers of different diseases, such as breast cancer and prostate cancer, were detected with high accuracy. Moreover, combined with immunomagnetic separation of circulating tumor cells (CTCs) from blood, a visual read-out for detection of CTCs was established, which has promising applications in clinical diagnosis, environmental monitoring, and food quality control only using naked eyes.

Strategy To Fabricate Naked-Eye Readout Ultrasensitive Plasmonic Nanosensor Based on Enzyme Mimetic Gold Nanoclusters.

It is broadly interesting but remains a big challenge to explore nanomaterials-based methods to enable naked-eye observation and determination of ultratrace biomarkers and drugs. In this study, we developed a straightforward and extendable plasmonic nanosensor to enable visually quantitative determination of ultratrace target molecules through combining the use of enzyme-mimetic gold nanoclusters (AuNCs). Starting from sandwiched antibody-antigen (i.e., an analyte)-antibody structure, we conjugated AuNCs on the outer layer antibody to catalyze the decomposition of hydrogen peroxide used to reduce HAuCl4 into gold nanopartilces (AuNPs) for naked eye readout. This strategy is in theory applicable to all immunoreactions available and the protocol proposed to attach AuNCs onto an antibody is suitable to all proteins. The applicability of this type of nanosensor was validated by the determination of various ultratrace analytes such as protein avidin, breast cancer antigen, thyroid hormone, and even methamphetamine (MA), giving a naked-eye-readout limit of detection (LOD), down to 1.0 × 10(-20) M protein avidin, 7.52 × 10(-14) U/mL breast cancer antigen 15-3, 2.0 × 10(-15) mg/mL 3,5,3'-L-triiodothyronine and 2.3 × 10(-18) mg/mL MA. This strategy is thus considered an ultrasensitive way to fabricate plasmonic nanosensors, having wide and invaluable application potential in clinical, biological, and environmental studies, and in food quality control.

Colorimetric and ultra-sensitive fluorescence resonance energy transfer determination of H2O2 and glucose by multi-functional Au nanoclusters.

Ultra-sensitive colorimetric determination of H2O2 is accomplished based on the intrinsic peroxidase-like activity of Au nanoclusters (AuNCs) stabilized by glutathione (GSH). The color change of 3,3,5,5-tetramethylbenzidine (TMB) catalyzed by AuNCs offers an indirect method to measure glucose. This sensing platform makes use of a dual optical signal change, including the color change in an aqueous solution under visible light illumination and an ultra-sensitive fluorescent assay arising from efficient fluorescence resonance energy transfer (FRET) between the AuNCs and oxidized TMB. The detection limits of H2O2 and glucose are 4.9 × 10(-13) M and 1.0 × 10(-11) M, respectively. In addition, enhanced fluorescence is observed from the AuNCs due to the use of ethanol which produces clear changes in the quantum yield and lifetime of the AuNCs. The quantum yield of AuNCs is enhanced from ∼12.5% as an isolated fluorophore to 38.9% in an AuNCs-ethanol complex. The enhanced fluorescence lowers the detection limits of H2O2 and glucose by 2 orders of magnitude compared to those attained from the original AuNCs.