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Label-free immunosensors based on a novel multi-amplification signal strategy of TiO2-NGO/Au@Pd hetero-nanostructures
摘要： A label-free electrochemical immunosensor for quantitative detection of human epididymis specific protein 4 antigen (HE4 Ag) was developed by a novel multi-amplification signal system. The multi-amplification signal system was formed by loading bimetallic Au@Pd holothurian-shaped nanoparticles (Au@Pd HSs) on titanium oxide nanoclusters functionalized nitrogen-doped reduced graphene oxide (TiO2-NGO). The Au@Pd HSs were obtained via seed-mediated approach with in-situ grown palladium nanoarms on gold nanorods (Au NRs) surfaces, which possessed good electrocatalysis for hydrogen peroxide (H2O2) reduction and excellent biocompatibility. The TiO2-NGO with the high catalytic activity and large specific surface area was synthesized by hydrothermal method. Using H2O2 as an electrochemically active substrate, the prepared label-free electrochemical immunosensor based on the TiO2-NGO/Au@Pd HSs hetero-nanostructures as the signal amplification platform exhibited excellent selectivity, reproducibility and stability for the detection of HE4 Ag. Meanwhile, the linear range from 40 fM to 60 nM with the detection limit of 13.33 fM (S/N = 3) was obtained, indicating the immunosensor offers a promising method for clinical detection of HE4 Ag.
关键词： Au@Pd nanoparticles,Titanium oxide,Label-free electrochemical immunosensor,Nitrogen-doped reduced graphene oxide,Human epididymis specific protein 4
更新于2025-09-23 15:23:52
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ZnO/porous carbon composite from a mixed-ligand MOF for ultrasensitive electrochemical immunosensing of C-reactive protein
摘要： Carbon-based nano-composite materials obtained via simple thermolysis of metal-organic framework (MOF) have competitive virtues in accordance of layered porosity, controllable morphologies, and easily functionalizing with other metal/metallic oxides or hetero atoms. These make them directly as high activity catalysts or supports for various electrochemical sensor. Herein, we developed a novel ZnO/porous carbon matrix (ZnO/MPC)-based electrochemical immunosensing through thermolysis of a mixed-ligand MOF (Zn-BDC-TED) for real sample analysis of C-reactive protein. The ZnO/MPC and ionic liquid (IL) composite membrane modified electrode displayed prominent conductivity and biocompatibility for ultrasensitive detection of C-reactive protein (CRP). Subsequently, the step-by-step assembly process of the CRP immunosensor was monitored by electrochemical measurements including cyclic voltammogram (CV) and electrochemical impedance spectra (EIS). After the parameter optimization, the differential pulse voltammetry (DPV) response decreased linearly with the logarithm of CRP levels in an extensive range of 0.01–1000 ng·mL?1, and the detection limit was as low as 5.0 pg·mL?1. Meanwhile, the lable-free immunosensor also showed excellent selectivity, reproducibility and stability. We believe that ZnO/MPC composite and many carbon-based nano-composite materials obtained via simple thermolysis of MOF will be a prospective platform for sensitive detecting other biomarkers.
关键词： ZnO/MPC,C-reactive protein,Electrochemical immunosensor,Pyrolysis,Lable-free
更新于2025-09-23 15:22:29
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Direct culture-free electrochemical detection of cells in milk based on quantum dots-modified nanostructured dendrons
摘要： With regard to global food safety and preventing the spread of diseases caused by foodborne pathogens or their toxins, there is an increasing need for simple and rapid methods for the screening of such pathogens. We aimed to develop a fast and efficient biosensor for the screening of milk samples contaminated by Salmonella spp. and provide a quick and cost-effective method as an alternative to the time-consuming conventional cultivation- or PCR-based approaches. We exploited a simple but highly specific technique whereby bacterial cells were separated immunomagnetically, with subsequent reaction with conjugate; i.e. specific IgG molecule labelled with an electrochemically potent indicator. The unique structure of this indicator exploits the benefits of hyperbranched dendron molecules and heavy metal–derived quantum dots (QDs). Square-wave anodic stripping voltammetry (SWASV) using of screen-printed carbon electrodes with in situ formed Bi(III) film (BiSPCE) was used for the detection and quantification of metal ions released from the QDs (CdTe) after their acidic dissolution. The metal ion signals proportionally correlate with the amount of captured bacteria cells. By this method, the presence of Salmonella spp. was proven in 2.5 hours even in minimal number of bacterial cells (4 CFU) in 1 mL of the sample.
关键词： Salmonella spp.,Electrochemical immunosensor,Quantum dots,Stripping voltammetry,Foodborne pathogen,Nanostructured dendrons
更新于2025-09-19 17:13:59
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Sensitive Detection of Prostate Specific Antigen Based on Copper Ions Doped Ag-Au Nanospheres Labeled Immunosensor
摘要： A sandwich-type electrochemical immunosensor was designed for quantitative detection of prostate speci?c antigen (PSA). Gold-platinum bimetallic functionalized tin oxide graphene (GS-SnO2-Au@Pt) has a large speci?c surface area, good conductivity and biocompatibility, which was used as the sensing interface to capture PSA coating antibody (Ab1). The copper ions doped Ag-Au nanospheres (Cu2+@Ag-Au) was prepared and used as a label of PSA labeling antibody (Ab2), which generated high intensive electrochemical redox signal based on the reduction reaction of Cu2+. The L-cysteine was applied as a bridge to connect Au nanoparticles (NPs) and Ag NPs, and to keep the nanosized gap between Au nuclear and Ag shell. This structure not only makes full advantage of space effect to load more Ag NPs but also increases the speci?c surface area for loaded more Cu2+. The proposed immunosensor with a wide range (10 pg mL?1 to 100 ng mL?1) and a low detection limit (3.84 pg mL?1) shows excellent performance in the detection of PSA. The results indicate that proposed immunosensor provides a promising application for the quantitative detection of biomolecules in serum samples.
关键词： Cu2+@Ag-Au,prostate speci?c antigen,GS-SnO2-Au@Pt,electrochemical immunosensor,signal amplification
更新于2025-09-11 14:15:04