1.
DNA-templated copper nanoparticles as signalling probe for electrochemical determination of microRNA-222.
Wang, Y, Meng, W, Chen, X, Zhang, Y
Mikrochimica acta. 2019;(1):4
Abstract
An ultrasensitive electrochemical biosensor is described for the determination of microRNAs. It is based on the use of DNA-templated copper nanoparticles (Cu NPs) as signalling probe. MicroRNA-222 was selected as the model analyte. The probe was obtained from two different oligonucleotides (containing complementary bases) via hybridization chain reaction to form long DNA concatemers as template. The Cu NPs were formed by reaction of ascorbate with copper sulfate. The biosensor was fabricated as follows: (a) Capture probe (cDNA) with a thiolated group was immobilized on reduced graphene oxide modified with gold nanoparticles (rGO/Au NPs), (b) materials was placed on a glassy carbon electrode (GCE); (c) the modified electrode (cDNA/rGO/Au NPs/GCE) was sequentially hybridized with microRNA-222 and signal probe; this results in the formation of a sandwich structure of cDNA-microRNA-signal probe on surface of the modified electrode. Differential pulse voltammetry was employed to record the electrochemical response of biosensor in pH 6.0 solution. As a result, a sensitive oxidation current with a peak potential at 0.10 V (vs. SCE) was obtained corresponding to Cu NPs. The experimental conditions were optimized. Under optimal conditions, the biosensor exhibited wide linear response range (0.5 fM to 70 nM) and low limit of detection (0.03 fM; at S/N = 3). The assay possesses high selectivity and can discriminate analyte microRNA from single-base mismatched microRNA. Graphical abstractA sensitive electrochemical biosensor is described for the determination of microRNA-222 by using a dsDNA-templated Cu NPs as signalling probe. (A) represents the preparation of signal probe, and (B) represents the fabrication of electrochemical microRNA sensor.
2.
Non-enzymatic electrochemical biosensor based on Pt NPs/RGO-CS-Fc nano-hybrids for the detection of hydrogen peroxide in living cells.
Bai, Z, Li, G, Liang, J, Su, J, Zhang, Y, Chen, H, Huang, Y, Sui, W, Zhao, Y
Biosensors & bioelectronics. 2016;:185-94
Abstract
A highly sensitive non-enzymatic electrochemical sensor based on platinum nanoparticles/reduced graphene oxide-chitosan-ferrocene carboxylic acid nano-hybrids (Pt NPs/RGO-CS-Fc biosensor) was developed for the measurement of hydrogen peroxide (H2O2). The RGO-CS-Fc nano-hybrids was prepared and characterized by UV-vis spectrum, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectrometer and electrochemical impedance spectroscopy. Under optimal experimental conditions, the Pt NPs/RGO-CS-Fc biosensor showed outstanding catalytic activity toward H2O2 reduction. The current response of the biosensor presented a linear relationship with H2O2 concentration from 2.0×10(-8)M to 3.0×10(-6)M with a correlation coefficient of R(2)=0.9968 and with logarithm of H2O2 concentration from 6.0×10(-6)M to 1.0×10(-2)M with a correlation coefficient of R(2)=0.9887, the low detection limit of 20nM was obtained at the signal/noise (S/N) ratio of 3. Moreover, the Pt NPs/RGO-CS-Fc biosensor exhibited excellent anti-interference capability and reproducibility for the detection of H2O2. The biosensor was also successfully applied for the detection of H2O2 from living cells containing normal and cancer cells. All these results prove that the Pt NPs/RGO-CS-Fc biosensor has the potential application in clinical diagnostics to evaluate oxidative stress of different living cells.
3.
Highly sensitive electrochemical impedance spectroscopy immunosensor for the detection of AFB1 in olive oil.
Yu, L, Zhang, Y, Hu, C, Wu, H, Yang, Y, Huang, C, Jia, N
Food chemistry. 2015;:22-6
Abstract
Aflatoxin produced by Aspergillus flavus and Aspergillus parasiticus are commonly found in olive and its derivatives. Aflatoxin B1 (AFB1) is a predominant toxin detected abundantly and has been implicated in the etiology of human hepatocellular carcinoma. This study proposes a sensitive and convenient electrochemical impedance spectroscopy (EIS) method for determining AFB1 by MWCNTs/RTIL composite films-based immunosensor. The calibration curve for AFB1 was linear in the range of 0.1-10ngmL(-1) with the limit of detection (LOD) 0.03ngmL(-1). The presence of MWCNTs warrant fast electron transfer, and the ionic liquid provides a benign microenvironment for antibody. The experimental parameters, such as pH and incubating time, have been investigated and optimized. Furthermore, the detection of AFB1 is presented to test this method after extracted from olive oils. It can be anticipated that this method would be used for the detection of AFB1 in various agriculture products and vegetable oils.