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An fluorescent aptasensor for sensitive detection of tumor marker based on the FRET of a sandwich structured QDs-AFP-AuNPs
摘要： The detection of alpha-fetoprotein (AFP) is of great importance for hepatocellular carcinoma (HCC) diagnosis, but it needs to be further improved because of poor sensitivity and complicated operating steps. In this paper, a simple and sensitive homogeneous aptasensor for AFP has been developed based on F?rster resonance energy transfer (FRET) where the AFP aptamer labeled luminescent CdTe quantum dots (QDs) as a donor and anti-AFP antibody functional gold nanoparticles (AuNPs) as an acceptor. In the presence of AFP, the bio-affinity between aptamer, target, and antibody made the QDs and AuNPs close enough, thus the fluorescence of CdTe QDs quenched though the FRET between QD and AuNP. The fluorescent aptasensor for AFP showed a concentration-dependent decrease of fluorescence intensity in the low nanomolar range and a detecting linear range of 0.5-45 ng mL?1, with a detection limit of 400 pg mL?1. Moreover, this homogeneous aptasensor is simple and reliable, and obtained satisfying results for the detection of AFP in human serum samples. With more and more aptamers for biomarkers have been selected gradually, this approach could be easily extended to detection of a wide range of biomarkers. The proposed aptasensor has great potential for carcinoma screening in point-of-care testing and even in field use.
关键词： alpha fetoprotein (AFP),fluorescent aptasensor,biomarker,hepatocellular carcinoma,F?rster resonance energy transfer (FRET)
更新于2025-09-23 15:23:52
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A robust covalent coupling scheme for the development of FRET aptasensor based on amino-silane modified graphene oxide
摘要： In recent years, numerous aptamers have been physisorbed on graphene oxide (GO) to develop FRET based aptasensors based on the high fluorescence quenching efficiency of GO. However, physisorbed aptasensors show poor signal reversibility and reproducibility as well as nonspecific probe displacement and thereby, are not suitable for many analytical applications. To overcome these problems when working with complex biological samples, we developed a facile and robust covalent surface functionalization technique for GO-based fluorescent aptasensors using a well studied adenosine triphosphate (ATP) binding aptamer (ABA). In the scheme, GO is first modified with amino-silane, and further with glutaraldehyde to create available carbonyl groups for the covalent attachment of a fluorophore and an amino dual modified ABA. The surface modification method was characterized by zeta potential, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The linearity, sensitivity, selectivity and reversibility of the resulting GO based covalent aptasensor was determined and systematically compared with the physisorbed aptasensor. While both sensors showed similar performance in terms of sensitivity and linearity, better selectivity and higher resistance to nonspecific probe displacement was achieved with the developed covalent ABA sensor. The surface modification technique developed here is independent from the aptamer sequence and therefore could be used universally for different analytical applications simply by changing the aptamer sequence for the target biomolecule.
关键词： aptamer,physisorption,EDC/NHS,fluorescent aptasensor,Graphene oxide,glutaraldehyde,amino-silane,covalent conjugation
更新于2025-09-23 15:21:01
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Determination of Dopamine by a Label-Free Fluorescent Aptasensor Based on AuNPs and Carbon Quantum Dots
摘要： In order to reduce the complex modification process and obtain a fast and label-free aptasensor, a label-free fluorescent aptasensor based on gold nanoparticles (AuNPs) and carbon quantum dots (CQDs) was constructed for rapid determination of dopamine (DA). In the absence of DA, CQDs were adsorbed on the surface of AuNPs through the electrostatic force between CQDs and aptamer, which led to the fluorescence quenching of CQDs. When DA were added, they combined with the corresponding aptamers with higher affinity and selectivity, resulting in CQDs far from the surface of AuNPs and thus the fluorescence intensity of CQDs was recovered. Under the optimal condition, the fluorescence intensity of the released CQDs was linearly proportional to the concentration of DA in a range of 5×10-8~2.5×10-4mol/L with a detection limit of 1×10-8mol/L. Moreover, the aptasensor exhibited a satisfactory detection result of DA in human serum samples. This study provided a more effective method to detect a broad range of targets by using appropriate aptamers, holding great potential in the field of food safety and biomedical diagnostics.
关键词： Label-free,Gold nanoparticles,Fluorescent aptasensor,Carbon quantum dots
更新于2025-09-11 14:15:04