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Hosta??guest recognition coupled with triple signal amplification endows an electrochemiluminescent biosensor with enhanced sensitivity
摘要： We demonstrate for the first time that the host-guest recognition coupled with triple signal amplification endows the electrochemiluminescent (ECL) biosensor with enhanced sensitivity for uracil DNA glycosylase (UDG) assay. This biosensor exhibits good selectivity and extremely high sensitivity, and it can be used to screen the UDG inhibitors and measure the cellular UDG activity as well.
关键词： triple signal amplification,sensitivity,electrochemiluminescent biosensor,uracil DNA glycosylase,host-guest recognition
更新于2025-09-19 17:13:59
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Sensitive electrochemical aptasensor for detecting EpCAM with silica nanoparticles and quantum dots for signal amplification
摘要： The epithelial cell adhesion molecule (EpCAM) is a known biomarker of circulating tumor cells that plays an important role in tumor metastasis. The detection of EpCAM is vital for personalized diagnosis and therapy but is challenging because of its extremely low concentration in peripheral blood. In our work, an electrochemical aptasensor has been developed to quantitatively detect EpCAM at low concentrations. A gold electrode modified with an aptamer can capture EpCAM, which can then be further recognized by a second aptamer acting as a signal reporter. To amplify the signal, a silica nanoparticle/CdSe complex has been designed to enhance the detection system. First, silica nanoparticles were synthesized to act as carriers for loading many CdSe quantum dots which are capable of binding with the second aptamer by biotin-streptavidin interactions. A molecule of EpCAM can bind with numerous CdSe quantum dots (QDs) to realize significant signal amplification. By stripping square wave voltammetry (SSWV), concentrations down to 10 aM EpCAM can be successfully detected and quantified based on the newly developed aptasensor. The detection linear range is from 10 aM to 100 pM. This principle can also be extended to other biomarkers when a suitable aptamer or antibody is available. This aptasensor is expected to be a potential tool for the diagnosis, therapeutic evaluation and personalized medical care of cancer patients.
关键词： Quantum dots,Signal amplification,Electrochemical aptasensor,Tumor biomarkers
更新于2025-09-16 10:30:52
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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
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A Novel Fluorescence Switch for MicroRNA Imaging in Living Cells based on DNAzyme Amplification Strategy.
摘要： MicroRNAs (miRNAs) play important roles in the regulation of target gene expression and cell development. Therefore, developing of accurate and visual detection methods for miRNAs is important for early diagnosis of cancer. In this study, we established a visual detection method for miRNA 155 based on DNAzyme amplification strategy in living cells. MnO2 nanosheets were employed to deliver Locked DNAzyme and Substrate DNA into cells. AuNPs-Probe were taken up by cells autonomously. Then, MnO2 nanosheets were reduced to Mn2+ by glutathione (GSH) in cells and DNA modules were released. MiRNA 155 took away Locker DNA by strand displacement reaction to activate the DNAzyme. Then the DNAzyme cleaved substrate DNA and released single-stranded DNA named Key DNA. Key DNA opened the hairpin DNA that modified on gold nanoparticles (AuNPs) and turn on the fluorescence of cy5. One target miRNA led to plenty of released Key DNA when lots of substrate DNA were added. Thus, the visual detection of miRNA 155 in living cells would be initiated. Under confocal laser microscopy, the fluorescence was obviously observed in tumor cells but not in normal cells. The method has a linear range from 0.1 nM to 10 nM and a low detection limit of 44 pM in vitro detection.
关键词： DNA walker,microRNA,AuNPs,Fluorescence imaging,MnO2,DNAzyme,Signal amplification
更新于2025-09-09 09:28:46
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Restriction of Molecular Rotors in Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets for Sensing Signal Amplification
摘要： Covalent organic frameworks (COFs) have emerged as promising crystalline porous materials with well-defined structures, high porosity, tunable topology and functionalities suitable for various applications. However, studies of few-layered ultrathin two-dimensional (2D) COF nanosheets, which may lead to unprecedented properties and applications, are still limited. Herein we report the targeted synthesis of three azine-linked and imine-linked 2D COFs named NUS 30-32 using monomers containing aggregation-induced emission (AIE) rotor-active tetraphenylethylene (TPE) moieties, affording micro- and meso- dual pores in NUS-30 and NUS-32, and triple pores in NUS-31. For the first time, we demonstrate that these isostructural bulk COF powders can be exfoliated into ultrathin 2D nanosheets (2 – 4 nm thickness) by temperature-swing gas exfoliation approach. Compared with TPE monomers and COF model compounds, the AIE characteristic of NUS 30-32 nanosheets is distinctly suppressed due to the covalent restriction of the AIE molecular rotors in the confined 2D frameworks. As a result, the enhancement of conjugated conformations of NUS 30-32 nanosheets with unusual structure relaxation show signal amplification effect in biomolecular recognition of amino acids and small pharmaceutical molecules (L-dopa), exhibiting much higher sensitivity than their stacked bulk powders, TPE monomer, and COF model compound. Moreover, the binding affinity of the COF nanosheets toward amino acids can be controlled by increasing the number of azine moieties in the structure. Density functional theory (DFT) calculations reveal that binding affinity control results from the crucial geometric roles and stronger host-guest binding between azine moieties and amino acids. In addition, we demonstrate that minimal loading of the NUS-30 nanosheets in composite membranes can afford excellent performance for biomolecule detection. Our findings pave a way for the development of functional ultrathin 2D COF nanosheets with precise control over the nature, density, and arrangement of the binding active sites involved in enhanced molecule recognition.
关键词： molecular rotors,Covalent organic frameworks,aggregation-induced emission,biomolecular recognition,signal amplification,two-dimensional nanosheets
更新于2025-09-04 15:30:14
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Voltammetric immunoassay of human IgG based on the release of cadmium(II) from CdS nanocrystals deposited on mesoporous silica nanospheres
摘要： The authors describe a nanocomposite that was obtained by in-situ deposition of CdS nanocrystals on mesoporous silica nanospheres (MSNs), and its use in an electrochemical immunoassay of human immunoglobulin G (HIgG). The MCN/CdS nanocomposite was covalently modified with the antibodies against HIgG and then employed in a voltammetric immunoassay at antibody-functionalized magnetic beads. Through sandwich immunoreaction, the MCN/CdS nanoprobes are quantitatively captured onto the magnetic beads where numerous Cd(II) ions are released in an acidic solution. The Cd(II) can be detected by anodic stripping voltammetry at a typical working potential of ?0.78 V (vs. Ag/AgCl). In combination with the high loading of CdS on MSNs, the use of the stripping voltammetric analysis renders the method high sensitivity. A wide linear range varying from 0.01 to 100 ng mL?1 is obtained for HIgG detection with a lower detection limit at 2.9 pg mL?1. In addition, the preparation of the nanoprobe is inexpensive. The magnetic bead-based assay does not require complex manipulations. Therefore, this method is deemed to possess a wide scope in that it may be applied to other immunoassays.
关键词： Magnetic beads,Anodic stripping voltammetry,Immunosensor,Nanoprobe,Signal amplification
更新于2025-09-04 15:30:14