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A Glucose Oxidase-Instructed Fluorescence Amplification Strategy for Intracellular Glucose Detection
摘要： The accurate detection of glucose in the cellular level remains a big challenge. In this study, a signal amplification strategy mediated by silver nanocube (AgNC), glucose oxidase (GOx) and silver ion fluorescence probe (denoted as AgNC-GOx/Ag+-FP) is proposed for amplified intracellular glucose detection. The AgNC is oxidized into Ag+ by H2O2 generated from the GOx-catalyzed glucose oxidation reaction, and Ag+ remarkably enhances the red fluorescence of Ag+-FP. Our results show that the AgNC-GOx/Ag+-FP is highly sensitive and specific to glucose and H2O2. Afterwards, the feasibility of using AgNC-GOx/Ag+-FP to detect intracellular glucose is verified in five different cell lines. In summary, a sensitive and specific fluorescence amplification strategy has been developed for intracellular glucose detection.
关键词： intracellular glucose,silver nanocube,fluorescence probe,glucose oxidase,signal amplification
更新于2025-11-19 16:56:35
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Zero background and triple-signal amplified fluorescence aptasensor for antibiotics detection in foods
摘要： It's important to eliminate matrix interference for accurate detecting antibiotic residues in complex food samples. In this study, we designed a zero-backgrounded fluorescence aptasensor to achieve on-site detection of antibiotic residues, with chloramphenicol (CAP) as representative analyte. Moreover, a three stir-bars assisted target recycling system (TSBTR) was designed to achieve triple signal amplification and increase the sensitivity. The bars included one magnetic stir-bar modified with two kinds of long DNA chains, and two gold stir-bars modified with Y shape-duplex DNA probes respectively. In the presence of CAP, the target could recurrently react with the probes on the bars and replace a large amount of long DNA chains into supernatant. After then, the bars were taken out and SYBR green dye was added to the solution. The dye can specifically intercalate into the duplex structures of DNA chains to emit fluorescence while not emitting a signal in its free state. Under the optimized experimental conditions, a wide linear response range of 5 orders of magnitude from 0.001 ng mL?1 to 10 ng mL?1 was achieved with a detection limit of 0.033 pg mL?1 CAP. The assay was successfully employed to detect CAP in food samples (milk & fish) with consistent results with ELISA's. High selectivity and sensitivity were attributed to the zero background signal and triple signal-amplification strategy. Moreover, the detection time can be shortened to 40 min due to that three signal amplified process can occur simultaneously. The fluorescent aptasensor was also label- and enzyme-free. All these ensure the platform to be rapid, cost-effective, easily-used, and is especially appropriate for detection antibiotics in food safety.
关键词： Three stir-bars assisted target recycling,Triple signal amplification,Zero background signal,Fluorescence aptasensor,Antibiotics
更新于2025-11-19 16:46:39
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Dual-Signal Amplification Strategy for miRNA Sensing with High Sensitivity and Selectivity by Use of Single Au Nanowire Electrodes
摘要： MicroRNAs (miRNAs) have been applied as biomarkers and better detection of their expression profiles plays important roles in early diagnosis of cancers. In this work, a simple dual-signal amplification strategy has been used to construct a novel nanosensor on single Au nanowire electrodes (SAuNWEs) for miRNA-16 detection based on the “signal-on” and “signal-off” features during hybridization/de-hybridization process. The ferrocene-labeled aptamer capture probe (Fc-CP-16) is designed to hybridize with thiolated methylene blue-labeled DNA probe (MB-CP) on SAuNWE to form duplex DNA, and the addition of miRNA-16 can lead to the dissociation of duplex structure due to the highly matched sequences between miRNA-16 and Fc-CP-16. The remaining MB-CP can thus tend to recover its hairpin structure at the presence of Mg2+ through the hybridization of its complementary sequences. During this hybridization/de-hybridization process, the changes of Fc and MB oxidation peaks can be recorded, and there has a linear relationship between the sum of dual-signal changes (ΔI = ΔIMB + |ΔIFc|) and the logarithm of miRNA-16 concentrations, which can be used to detect miRNA-16. Including miRNA extraction, the dual-signal amplification strategy for miRNA sensing assay was carried out about 2 hours for the detection in real samples. This novel nanosensor has small dimension, good selectivity, rapid response and regeneration ability, which can satisfy the need for early cancer marker detection in cells/organelles.
关键词： nanosensors,single Au nanowire electrodes,dual-Signal Amplification Strategy,micro RNA
更新于2025-11-14 17:03:37
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Determination of 17β-estradiol by surface-enhanced Raman spectroscopy merged with hybridization chain reaction amplification on Au@Ag core-shell nanoparticles
摘要： The authors describe an aptamer-based assay for 17β-estradiol. It relies on the combined use of surface enhanced Raman scattering (SERS) and hybridization chain reaction (HCR). The aptamer against 17β-estradiol is applied as the recognition probes, and this results in excellent specificity. Specific recognition of target 17β-estradiol induce the freedom of DNA 2, which will open the stem-loop structure of probe 1 on the Au@Ag and form the partial dsDNA structure. With the nicking enzyme, the partial dsDNA will be hydrolyzed and the reside ssDNA on Au@Ag will form a small stem-loop structure. With the help of the other probe 2 modified Au@Ag and pre-immobilized probe 3 on the well of the microplate, an enzyme-free HCR can occur and tremendous Au@Ag can be assembled along the formed dsDNA in HCR, which can act as the excellent substrate for Raman measurement and greatly amplify the Raman signal of R6G on the Au@Ag. Afterwards, the key factor, ratio between probe 2-Au@Ag (P2) and probe1-Au@Ag (P1), affects the detection sensitivity is systematically optimized for the best sensing performance. The SERS signal of R6G, best measured at 1651 cm?1, increases linearly in the wide range from 1 pM to 10 nM. The detection limit can be as low as 0.1 pM.
关键词： Estrogen,Hybridization chain reaction,SERS,Food safety,Aptamer,Gold nanoparticle,Signal amplification,Environment monitoring
更新于2025-09-23 15:23:52
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Turn-On Fluorescence Aptasensor on Magnetic Nanobeads for Aflatoxin M1 Detection Based on an Exonuclease III-Assisted Signal Amplification Strategy
摘要： In order to satisfy the need for sensitive detection of Aflatoxin M1 (AFM1), we constructed a simple and signal-on fluorescence aptasensor based on an autocatalytic Exonuclease III (Exo III)-assisted signal amplification strategy. In this sensor, the DNA hybridization on magnetic nanobeads could be triggered by the target AFM1, resulting in the release of a single-stranded DNA to induce an Exo III-assisted signal amplification, in which numerous G-quadruplex structures would be produced and then associated with the fluorescent dye to generate significantly amplified fluorescence signals resulting in the increased sensitivity. Under the optimized conditions, this aptasensor was able to detect AFM1 with a practical detection limit of 9.73 ng kg?1 in milk samples. Furthermore, the prepared sensor was successfully used for detection of AFM1 in the commercially available milk samples with the recovery percentages ranging from 80.13% to 108.67%. Also, the sensor performance was evaluated by the commercial immunoassay kit with satisfactory results.
关键词： aptasensors,signal amplification,G-quadruplex,magnetic nanobeads,aflatoxin M1
更新于2025-09-23 15:22:29
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A novel intracellular signal amplification strategy for the quantification of ATP in single cells by microchip electrophoresis with laser induced fluorescence detection
摘要： An intracellular signal amplification strategy was developed for quantification of ATP in single cells by microchip electrophoresis with laser induced fluorescence detection. By using the method proposed, intracellular ATP levels in single Hela, HepG2 and HL-7702 cell were found in the range of 30～150, 30~140, and 19～120 fmol/cell, respectively.
关键词： laser induced fluorescence,ATP,microchip electrophoresis,single-cell analysis,signal amplification
更新于2025-09-23 15:21:01
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Surface-plasmon-coupled chemiluminescence amplification of silver nanoparticles modified immunosensor for high-throughput ultrasensitive detection of multiple mycotoxins
摘要： A novel surface-plasmon-coupled chemiluminescent immunosensor was developed for the detection of multiplex mycotoxins with ultrahigh sensitivity, high throughput and simplicity. The immunosensor was constructed by immobilizing carboxyl modified silver nanoparticles (AgNPs) and bovine serum albumin combined antigens sequentially on the glass chip modified with amino groups. The optical properties of AgNPs could amplify the chemiluminescence (CL) generated on the chip through the surface plasmon resonance phenomenon. Using a competitive immunoassay, the CL signals from all the sensing sites on the chip were collected simultaneously by a charge-coupled device for ultrasensitive analysis of multiple mycotoxins. Citrinin, aflatoxin B1 and ochratoxins A were selected as model analytes. Under optimal conditions, the surface-plasmon-coupled chemiluminescent immunosensor-based method presented wide linear ranges over 4 orders of magnitude and much lower limits of detection than previous work. The assay results of mycotoxins in red yeast rice samples using the proposed method were in good agreement with that using the liquid chromatography-mass spectrometry method. Its high selectivity, high throughput, acceptable stability and accuracy showed broad prospects in mycotoxin monitoring and evaluation of safety on Traditional Chinese Medicine.
关键词： Immunosensor array,Signal amplification,Silver nanoparticle,Multiplex immunoassay,Mycotoxins,Surface-plasmon-coupled chemiluminescence
更新于2025-09-23 15:21:01
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Signal amplification and quantification on lateral flow assays by laser excitation of plasmonic nanomaterials
摘要： Lateral flow assay (LFA) has become one of the most widely used point-of-care diagnostic methods due to its simplicity and low cost. While easy to use, LFA suffers from its low sensitivity and poor quantification, which largely limits its applications for early disease diagnosis and requires further testing to eliminate false-negative results. Over the past decade, signal enhancement strategies that took advantage of the laser excitation of plasmonic nanomaterials have pushed down the detection limit and enabled quantification of analytes. Significantly, these methods amplify the signal based on the current LFA design without modification. This review highlights these strategies of signal enhancement for LFA including surface enhanced Raman scattering (SERS), photothermal and photoacoustic methods. Perspectives on the rational design of the reader systems are provided. Future translation of the research toward clinical applications is also discussed.
关键词： gold nanoparticles,lateral flow assay,nanoparticle heating,signal amplification and quantification,SERS
更新于2025-09-23 15:19:57
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Signal amplified photoelectrochemical assay based on Polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction assembled through sandwich-type recognition model
摘要： A novel photoelectrochemical (PEC) sensing strategy with an amplified signal was proposed based on polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction. The sandwich-type detection model was applied to increase the sensitivity and favor the assembly of heterojunction structure. The heterojunction among PPy, g-C3N4 and WO3 highly improved the separation of photo-generated charges. Meanwhile, WO3 IOPCs with good optical performance were employed to enhance the light absorption of PEC detection electrode. With the simultaneous combination of these amplification techniques, the designed PEC sensor achieved high sensitivity with low limit of detection (LOD) as 0.004 nM (≈ 1.99 ng L?1) and admirable selectivity in the detection of oxytetracycline under visible light irradiation.
关键词： Sandwich-type,Signal amplification,Inverse opal photonic crystal,Photoelectrochemical,Heterojunction
更新于2025-09-23 15:19:57
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Surface Plasmon Enhanced Light Scattering Biosensing: Size Dependence on the Gold Nanoparticle Tag
摘要： Surface plasmon enhanced light scattering (SP-LS) is a powerful new sensing SPR modality that yields excellent sensitivity in sandwich immunoassay using spherical gold nanoparticle (AuNP) tags. Towards further improving the performance of SP-LS, we systematically investigated the AuNP size effect. Simulation results indicated an AuNP size-dependent scattered power, and predicted the optimized AuNPs sizes (i.e., 100 and 130 nm) that afford extremely high signal enhancement in SP-LS. The maximum scattered power from a 130 nm AuNP is about 1700-fold higher than that obtained from a 17 nm AuNP. Experimentally, a bio-conjugation protocol was developed by coating the AuNPs with mixture of low and high molecular weight PEG molecules. Optimal IgG antibody bioconjugation conditions were identified using physicochemical characterization and a model dot-blot assay. Aggregation prevented the use of the larger AuNPs in SP-LS experiments. As predicted by simulation, AuNPs with diameters of 50 and 64 nm yielded significantly higher SP-LS signal enhancement in comparison to the smaller particles. Finally, we demonstrated the feasibility of a two-step SP-LS protocol based on a gold enhancement step, aimed at enlarging 36 nm AuNPs tags. This study provides a blue-print for the further development of SP-LS biosensing and its translation in the bioanalytical field.
关键词： signal amplification,surface plasmon resonance,gold nanoparticles,surface plasmon enhanced light scattering,gold enhancement
更新于2025-09-19 17:15:36