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An ultrasensitive homogeneous aptasensor for carcinoembryonic antigen based on upconversion fluorescence resonance energy transfer
摘要： Carcinoembryonic antigen (CEA) has been recognized as one of the most important tumor markers. Herein, we reported an ultrasensitive homogeneous aptasensor based on fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) and graphene oxide (GO) for CEA detection. The CEA aptamer modified UCNPs can bind to the surface of GO through π-π stacking interaction, resulting in fluorescence quenching due to the energy transfer from UCNPs to GO. After the introduction of CEA, the CEA aptamer preferentially combined with CEA to form three-dimensional structure which made UCNPs-aptamer dissociate from the GO, blocking the energy transfer process. The fluorescence of UCNPs was accordingly restored in a CEA concentration-dependent manner both aqueous solution and human serum samples. The aptasensor could monitor CEA level directly in human serum and the results were strongly correlated with commercial chemiluminescence kits. The excellent detection performance suggested promising prospect of the aptasensor in practical application.
关键词： Upconversion Nanoparticles,Graphene Oxide,Fluorescence Resonance Energy Transfer,CEA,Aptasensor
更新于2025-09-23 15:21:01
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Determination of BCM-7 based on an ultrasensitive aptasensor fabricated of gold nanoparticles and ZnS quantum dots
摘要： In this study, an ultrasensitive electrochemical aptasensor for the determination of the β-casomorphin 7 (BCM-7) as a promising biomarker of autism disorder is introduced. According to the proposed strategy, a glassy carbon electrode (GCE) was modi?ed by thiourea capped-ZnS QDs (ZnS-QDs) and gold nanoparticles (AuNPs) to further immobilization the amino-aptamer (NH2-Apt) on its surface. The NH2-Apt as a receptor of the BCM-7 was attached to the embedded surface via a formation of the Au–N bonds between the AuNPs and amino groups of the Apt. The evaluation of aptasensor by various electrochemical techniques exhibited successful sensing of the BCM-7 under two broad linear concentration ranges from 1 fM to 0.6 μM with a limit of detection (LOD) down to 350 aM. Also, the performance of the aptasensor in BCM-7 detection in real human urine samples was satisfactorily investigated. These ?ndings may facilitate distinguish of this challenging disorder and help human health.
关键词： Thiourea capped-ZnS QDs,β-casomorphin 7,Glassy carbon electrode,Gold nanoparticles,Aptasensor,Autism
更新于2025-09-23 15:21:01
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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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Construction of the 0D/2D heterojunction of Ti3C2Tx MXene nanosheets and iron phthalocyanine quantum dots for the impedimetric aptasensing of microRNA-155
摘要： A promising nanocarrier of the complementary DNA (cDNA) toward miRNA-155 was synthesized on the basis of the nanohybrid type of Ti3C2Tx MXene nanosheets decorated using iron phthalocyanine quantum dots (FePc QDs) (denoted as Ti3C2Tx@FePcQDs) to construct a novel ultrasensitive impedimetric aptasensing system for microRNA-155 (miRNA-155). Owing to π–π* stacking interaction between Ti3C2Tx nanosheets and FePc QDs, the homogeneous nanostructure of the Ti3C2Tx@FePcQD nanohybrid that comprises mixed-valence states (Ti2+/Ti3+ and Fe2+/Fe3+), multicomponent (Ti-O and Ti-C), and various N-related groups was achieved. The constructed Ti3C2Tx@FePcQDs-based aptasensor displayed an ultrahigh sensitivity for detecting miRNA-155 with a low detection limit of 4.3 aM (S/N = 3) within the miRNA-155 concentration ranging from 0.01 fM to 10 pM. Compared with the individual component-based aptasensors and other reported miRNA-155 aptasensors, the proposed impedimetric aptasensing system exhibited substantial merits of a feasible preparation process, non-use of labels or electrochemical indicators, fast response time, and comprehensive sensing performances for detecting miRNA-155. This strategy for determining miRNAs can extensively be applied as the platform for anchoring other kinds of aptamers in detecting diverse targets, thus indicating its great potential application for the early diagnosis of cancer biomarkers.
关键词： Impedimetric aptasensing,Iron phthalocyanine,Nanohybrid,Detection of miRNA-155,Ti3C2Tx MXene nanosheets,Electrochemical aptasensor
更新于2025-09-23 15:19:57
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Plasmonic enhanced photoelectrochemical aptasensor with D-A F8BT/g-C3N4 heterojunction and AuNPs on a 3D-printed device
摘要： D-A F8BT/g-C3N4 type II heterojunction nanocomposite was employed as photoelectrode material for photoelectrochemical (PEC) aptasensor based on rolling circle amplification (RCA) with the assistance of 3D-printed device for carcinoembryonic antigen (CEA) detection. D-A type F8BT improved photocurrent response of g-C3N4 nanosheet after forming D-A F8BT/g-C3N4 type II heterojunction which effectively constructed built-in electric field and reduced electron-hole recombination. With the introduction of DNA-AuNP probes by π-stacking interaction, the local plasmon resonance (LSPR) of AuNPs enhanced local electric field, promoted the generation of electron-hole and further improved photocurrent response. When target CEA was in presence of sensing platform, sandwich construction was formed between two kinds of CEA aptamers and CEA on magnetic beads, triggering the RCA reaction to produce repeated sequences. Partial sequences of complementary-DNA in combination with RCA results was digested by Exo III enzyme to release signal-DNA, detaching DNA-AuNP probes from the surface of the F8BT/g-C3N4 by complementation, causing the attenuation of LSPR and the decrease of photocurrent response. Combing with 3D-printed device, this PEC aptasensor exhibited a linear response to CEA from 0.02 ng mL?1 to 50 ng mL?1 with detection limit of 6.7 pg mL?1, contributing to develop all organic polymer semiconductors as photoelectric materials in PEC study.
关键词： Type II heterojunction,Rolling circle amplification,Photoelectrochemical aptasensor,D-A F8BT/g-C3N4 nanocomposites,3D-printed device,Local surface plasmon resonance
更新于2025-09-23 15:19:57
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A SERS aptasensor for sensitive and selective detection of bis(2-ethylhexyl)phthalate
摘要： Bis(2-ethylhexyl)phthalate (DEHP) is an endocrine disruptor commonly present in plastic products, such as PVC tubes and water bottles. In this work, a surface enhanced Raman spectroscopy (SERS) based aptasensor was developed and utilized for rapid, easy, sensitive, and specific detection of trace DEHP. A DEHP aptamer was immobilized on magnetic particles. Raman reporter molecule conjugated silver nanoparticles were clustered and coated with silica to provide a stable SERS signal. The SERS silica particle was then functionalized with 1,2,4-benzenetricarboxylic acid 1,2-bis(2-ethylhexyl) ester to increase its affinity to the DEHP aptamer. In the presence of a sample with DEHP, the high-affinity SERS silica particle competes with the DEHP molecule to bind with the aptamer on the magnetic particle. By measuring the signal of free SERS silica particles in the supernatant after magnetic separation, the concentration of DEHP in the sample was quantitatively determined. The developed DEHP aptasensor had a detection range from 0.008 to 182 nM and a limit of detection (LOD) of 8 pM. The aptasensor also showed high selectivity when exposed to interferents with analogous structures. The aptasensor was successfully tested for the detection of DEHP spiked in tap water, bottled water, and a carbonate beverage. The developed SERS-based aptasensor provides a rapid, sensitive, and easy-to-use method for the quantitative detection of DEHP in environmental and food analysis.
关键词： silica particles,SERS,competitive binding,detection,DEHP,aptasensor
更新于2025-09-19 17:15:36
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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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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
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Chitosan-carbon quantum dots as a new platform for highly sensitive insulin impedimetric aptasensor
摘要： Considering the importance of measuring insulin in the prevention and diagnosis of diabetes-related illnesses, here we introduced an ultrasensitive electrochemical aptamer-based sensor for detection of insulin in human blood serum. In this research, carbon quantum dots (CQDs) were synthesized using simple, fast and cheap methods from candle soot. By dispersion of the CQDs in chitosan (Chi) matrix, homogenous CQD-Chit nano-composite was obtained. The experimental results demonstrate the good advantages of proposed CQD-Chit nano-composite, such as homogeneity, high stability and multiple amino groups for covalent immobilization of aptamer and fabrication of highly selective insulin aptasensor. CQD-Chit nano-composite was characterized by the transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDAX), Fourier transform infrared (FTIR) spectroscopy and electrochemical techniques. Under the optimized conditions with electrochemical impedance spectroscopy technique, a linear response ranges from 0.5 nM to 10 nM with the sensitivity of 80.07 ?/nM and the very low detection limit of 106.8 pM was obtained for insulin detection. The fabricated aptasensor is validated in comparison with standard methods for detection of insulin in human blood serum. Also, the analytical performances of the fabricated aptasensor can be a superiority compared to the current insulin electrochemical biosensors.
关键词： Modifies electrode,Biosensor,Impedimetric aptasensor,Carbon quantum dots,Insulin detection
更新于2025-09-11 14:15:04
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A multiplexed FRET aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide/Fe3O4 as single energy acceptor?
摘要： Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are the most common mycotoxins and often coexist in agricultural products, which are known to be a toxic superposition and even carcinogenic effects on humans. We proposed a multiplexed fluorescence resonance energy transfer (FRET) aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide (GO)/Fe3O4 as single energy acceptor. CdTe quantum dots emitting green (GQDs) and red (RQDs) fluorescence are modified by aptamers specifically for AFB1 and FB1 and used as dual energy donors. Compared with conventional FRET system based on GO quencher, GO/Fe3O4, a single energy acceptor, can not only quench the fluorescence of aptamer-modified GQDs and RQDs with different emission peaks simultaneously, but also be removed by effective magnetic separation to eliminate the interference of background. In the absence of GO/Fe3O4 nanocomposites, the aptamer modified GQDs and RQDs give off strong fluorescence under ultraviolet radiation. The fluorescence of GQDs and RQDs is quenched when GO/Fe3O4 nanocomposites is added to the system owing to the π–π stacking interaction between GO/Fe3O4 nanocomposites and GQDs- and RQDs-labeled aptamer. However, in the presence of AFB1 and FB1, the binding of aptamers to their specific targets will fold their single stranded structures and hinder the contact between base group in aptamers and GO/Fe3O4, which cause the fluorescence recovery of GQDs and RQDs. With the help of one step of magnetic separation, the supernatants can be collected for fluorescence analysis. After optimization of detection conditions, the developed method had a wider linear range of 10 pg mL?1–100 ng mL?1 for AFB1 and 50 pg mL?1–300 ng mL?1 for FB1 and showed no cross-reactivity with other closely related mycotoxins, respectively. The limit of detection for AFB1 and FB1 are calculated to be 6.7 and 16.2 pg mL?1 based on S/N=3. The detection of mycotoxins has been successfully realized in peanut samples and a new application field of FRET system is expected for various targets.
关键词： aptasensor,fluorescence resonance energy transfer,aflatoxin B1,fumonisin B1,simultaneous detection
更新于2025-09-11 14:15:04