Query: aptasensor

title: Competitive electrochemical aptasensor based on a cDNA ferrocene/MXene probe for detection of breast cancer marker Mucin1.
abstract: A competitive electrochemical aptasensor based on a cDNA ferrocene/MXene probe is used to detect the breast cancer marker Mucin1 (MUC1) MXene (Ti3C2) nanosheets with excellent electrical conductivity and large specific surface area are selected as carriers for aptamer probes. The ferrocene labeled complementary DNA (cDNA Fc) is first bound on the surface of MXene to form a cDNA Fc/MXene probe. Then, the MUC1 aptamer is fixed to the electrode by Au S bonds. The sensing electrode is named Apt/Au/GCE. After the probe is complementary to the aptamer, a cDNA Fc/MXene/Apt/Au/GCE aptasensor is fabricated. When the aptasensor is used for detection of MUC1, a competitive process happens between the cDNA ferrocene/MXene probe and MUC1, which makes cDNA Fc/MXene probe detach from the sensing electrode, resulting in a decrease in electrical signal. The difference in the corresponding peak current before and after the competition can be used to indicate the quantitative change in bound MUC1. The proposed competitive electrochemical aptasensor gives a wide linear range of 1.0 pM 10 mM and a low detection limit of 0.33 pM (S/N 3) which is promising for clinical diagnosis.

title: Ultrasensitive electrochemiluminescence aptasensor for kanamycin detection based on silver nanoparticle catalyzed chemiluminescent reaction between luminol and hydrogen peroxide
abstract: An ultrasensitive electrochemiluminescence (ECL) aptasensor for detection of kanamycin (KAN) was constructed by using the chemiluminescence properties of luminol hydrogen peroxide (H2O2) in alkaline solution. Silver nanoparticles (AgNPs) could act as effective catalyzer to accelerate H2O2 decomposition to produce various intermediate reactive oxygen species for signal amplification and thus increased the ECL intensity of luminol. When the target KAN was in the presence, ECL signal decreased obviously owing to the specific interaction between KAN and aptamer. Thus, the concentration of KAN could be determined according to the intensity of ECL. To further demonstrate the effect of aptasensor, we had conducted cyclic voltammetry on an electrochemical workstation and electrogenerated chemiluminescence analyzer, respectively. Upon the optimization of assay conditions, the proposed aptasensor displayed a wide linear range from 0.5 to 100 ng mL 1 with limit of detection of 0.06 ng mL 1. The as proposed aptasensor was not only capable of achieving a satisfactorily low detection limit but also possessed advantages of excellent accuracy, specificity and stability. Furthermore, this constructed ECL sensing platform was successfully applied to detect KAN in real samples and it would be of excellent potential to detect other antibiotics using the proposed method.

title: High affinity truncated aptamers for ultra sensitive colorimetric detection of bisphenol A with label free aptasensor.
abstract: The widespread exposure of bisphenol A (BPA) presents a significant risk to human health. A rapid, ultra sensitive and label free colorimetric aptasensor using high affinity truncated aptamers was developed for BPA detection. Truncated 38 mer and 12 mer aptamers specific for BPA were obtained through rationally truncation from 63 mer BPA aptamer. The dissociation constants (Kd) of 38 mer and 12 mer aptamers were determined to be 13.17 nM and 27.05 nM. Then, truncated aptamers were used in label free colorimetric detection assays based on gold nanoparticles (AuNPs) The limit of detections of aptasensors using 38 mer and 12 mer aptamers were 7.60 pM and 14.41 pM, which were 265 fold and 140 fold lower than that of the aptasensor using 63 mer aptamer, respectively. The recovery rates in milk, orange juice and mineralized water samples were 93.88% to 107.30% Therefore, the developed BPA colorimetric aptasensor using truncated aptamers has great application prospects in food safety control and environmental monitoring.

title: Self polymerized Dopamine Decorated Au NPs and Coordinated with Fe MOF as a Dual Binding Sites and Dual Signal amplifying Electrochemical Aptasensor for the Detection of CEA.
abstract: Fabrication of functional electrochemical biosensor is a hot topic, however, precise and sensitive cancer detection in early clinical diagnosis is still a great challenge. Continuous efforts has been devoted to explore functional materials for this issue. In this work, we developed a dual binding sites and dual signal amplifying electrochemical aptasensor of self polymerized dopamine decorated Au and coordinated with Fe MOF (Au@PDA@Fe MOF) for the detection of carcinoembryonic antigen (CEA) Remarkably, Au@PDA@Fe MOF features high sensitivity, multiple active sites, good biocompatibility and excellent selectivity which is attributed to abundant COOH in porous Fe MOF and unsaturated Fe3+ sites on the surface of Fe MOF as the active binding sites grafting more NH2 functionalized CEA specific aptamer and redox PDA and Fe MOF accelerating the movement of electrons for dual signal amplifying. Meanwhile, the electrochemical aptasensor shows favorable repeatability with 1.82% Relative Standard Deviation (RSD) under five independent aptasensors and strong stability with only 3.3% degradation after 12 days of storage. In addition, the aptasensor has wide CEA detection range from 1 fg mL 1 to 1 mg mL 1 with a low detection limit of 0.33 fg mL 1 (S/N=3) Furthermore, the aptasensor it is feasible for accurate and quantitative detection of CEA in serum samples with RSD below 2.32% The satisfying results demonstrate promising applications of CEA aptasensor in practical sample analysis and lay an important foundation for other biomarkers detection in early clinical diagnosis.

title: Dual Channel Photoelectrochemical Ratiometric Aptasensor with up Converting Nanocrystals Using Spatial Resolved Technique on Homemade 3D Printed Device.
abstract: A near infrared light activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs) semiconductor nanocrystals based spatial resolved technique on a homemade 3D printing device in which a self regulating integrated electrode was designed for dual signal readout. The as prepared NaYF4:Yb,Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A1) and capture DNA (CA) were modified onto two working photoelectrodes (WP1 and WP2) through covalent binding, respectively, and then gold nanoparticle labeled CEA aptamer 2 (Au NP A2) was immobilized on the surface of functional WP2 for the formation of double stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP1, whereas the binding of the CEA with Au NP A2 could be released from the WP2 thanks to the highly affinity of CEA toward A2. The dual signal readout with the "signal off" of WP1 and "signal on" of WP2 were employed for the spatial resolved PEC (SR PEC) strategy to detect CEA as an analytical model. Combining NaYF4:Yb,Er UCNPs@CdTe nanocrystals with spatial resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL 1 to 5.0 ng mL 1 with a limit of detection of 4.8 pg mL 1 under 980 nm illumination. The SR PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed, and point of care biosensors.

title: Simultaneous detection of streptomycin and kanamycin based on an all solid state potentiometric aptasensor array with a dual internal calibration system
abstract: A novel potentiometric aptasensor array based on a 4 channel screen printed carbon electrode was developed with a dual internal calibration system for the simultaneous detection of streptomycin and kanamycin. Two channels were used as working channels for assembling the aptamers of the two targets, and the other two channels acted as calibration channels. The calibration channels functioned by immobilizing two all A sequences were employed to subtract the influence from the background matrix and further improve the detection accuracy. Consequently, under optimal conditions, this aptasensor array showed high sensitivity for the detection of streptomycin and kanamycin with detection limits of 9.66 pM and 5.24 pM, respectively, and corresponding linear response ranges of 10 pM 10 mM and 10 pM 1 mM, respectively. Moreover, it presented high specificity without mutual interference between the two targets or with other antibiotics and also demonstrated good repeatability. This aptasensor array was further applied to the simultaneous detection of streptomycin and kanamycin in real milk samples, and the results were validated by liquid chromatography mass spectrometry (LC MS) The results demonstrated satisfactory accuracy and precision and showed the great application potential of the aptasensor array with internal calibration for on site detection of multiple targets.

title: An electrochemical aptasensor based on gold modified MoS2/rGO nanocomposite and gold palladium modified Fe MOFs for sensitive detection of lead ions
abstract: In this work, an electrochemical aptasensor was proposed by using gold modified molybdenum disulfide/reduced graphene oxide (Au@MoS2/rGO) nanocomposite and gold palladium (AuPd) modified MIL 88 (Fe) metal organic frameworks (AuPd@Fe MOFs) for sensitive detection of lead ions (Pb2+ The 8 17 DNAzyme consisting of a substrate strand (Apt1) and a catalytic strand (Apt2) was used to construct the aptasensor. Au@MoS2/rGO nanocomposite was applied as the sensing platform to immobilize the mercapto group labeled Apt1. Meanwhile, AuPd@Fe MOFs was employed to label Apt2, which showed excellent catalytic ability toward H2O2. In the presence of Pb2+ the Apt1 of the DNAzyme was catalytically cut off, decreasing the amount of AuPd@Fe MOFs. The current response was correlated to the Pb2+concentration, thereby achieving Pb2+ detection. Under the optimal experimental conditions, the fabricated aptasensor showed a highly linear response for Pb2+ in the range from 5.0 pmol/L to 2.0 mmol/L, with a detection limit of 0.07 pmol/L. Additionally, the proposed electrochemical aptasensor exhibited excellent selectivity, stability and reproducibility. Moreover, the proposed aptasensor demonstrated good performance in real water sample analysis, making it promising for use in Pb2+ detection in environmental monitoring.

title: Localized surface plasmon resonance aptasensor for the highly sensitive direct detection of cortisol in human saliva
abstract: Cortisol, which is a stress biomarker that causes various mental disorders, is found in sweat, saliva, blood, and urine. Because mental disorders resulting from stress are a silent contributor to various diseases, the detection of cortisol level is an important step in their prevention. Here, we developed a highly sensitive, localized surface plasmon resonance (LSPR) aptasensor for the direct detection of cortisol in saliva. The LSPR aptasensor was constructed using gold nanoparticles of different sizes. Subsequently, the surface of the LSPR substrate was immobilized using an aptamer for capturing cortisol. The detection capability of the LSPR aptasensor was compared with that of the antibody immobilized sensor. The LSPR aptasensor displayed excellent detection capability for a wide range of cortisol concentrations extending from 0.1 1000 nM with a detection limit of 0.1 nM. In addition, the LSPR aptasensor was able to selectively detect cortisol among other substances with similar chemical structures (e.g. cortisone, corticosterone, progesterone, and triamcinolone) These results indicate that the LSPR aptasensor may be used for the highly sensitive and selective detection of cortisol in salivary samples.

title: A Sensitive Aptasensor Based on a Hemin/G Quadruplex Assisted Signal Amplification Strategy for Electrochemical Detection of Gastric Cancer Exosomes.
abstract: Emerging evidence indicates that exosomes derived from gastric cancer cells enhance tumor migration and invasion through the modulation of the tumor microenvironment. However, it remains a major problem to detect cancer specific exosomes due to technical and biological challenges. Most of the methods reported could not achieve efficient detection of tumor derived exosomes in the background of normal exosomes. Herein, a label free electrochemical aptasensor is presented for specific detection of gastric cancer exosomes. This platform contains an anti CD63 antibody modified gold electrode and a gastric cancer exosome specific aptamer. The aptamer is linked to a primer sequence that is complementary to a G quadruplex circular template. The presence of target exosomes could trigger rolling circle amplification and produce multiple G quadruplex units. This horseradish peroxidase mimicking DNAzyme could catalyze the reduction of H2 O2 and generate electrochemical signals. This aptasensor exhibits high selectivity and sensitivity toward gastric cancer exosomes with a detection limit of 9.54 x 102 mL 1 and a linear response range from 4.8 x 103 to 4.8 x 106 exosomes per milliliter. Therefore, this electrochemical aptasensor is expected to become a useful tool for the early diagnosis of gastric cancer.

title: Label free microfluidic paper based electrochemical aptasensor for ultrasensitive and simultaneous multiplexed detection of cancer biomarkers.
abstract: Simultaneous detection of multiple tumor biomarkers in body fluids could facilitate early diagnosis of lung cancer, so as to provide scientific reference for clinical treatment. This paper depicted a multi parameter paper based electrochemical aptasensor for simultaneous detection of carcinoembryonic antigen (CEA) and neuron specific enolase (NSE) in a clinical sample with high sensitivity and specificity. The paper based device was fabricated through wax printing and screen printing, which enabled functions of sample filtration and sample auto injection. Amino functional graphene (NG) Thionin (THI) gold nanoparticles (AuNPs) and Prussian blue (PB) poly (3,4 ethylenedioxythiophene) (PEDOT) AuNPs nanocomposites were synthesized respectively. They were used to modify the working electrodes not only for promoting the electron transfer rate, but also for immobilization of the CEA and NSE aptamers. A label free electrochemical method was adopted, enabling a rapid simple point of care testing. Experimental results showed that the proposed multi parameter aptasensor exhibited good linearity in ranges of 0.01 500 ng mL 1 for CEA (R2 0.989) and 0.05 500 ng mL 1 for NSE (R2 0.944) respectively. The limit of detection (LOD) was 2 pg mL 1 for CEA and 10 pg mL 1 for NSE. In addition, the device was evaluated using clinical serum samples and received a good correlation with large electrochemical luminescence (ECL) equipment, which would offer a new platform for early cancer diagnostics, especially in those resource limit areas.