1.
Mechanical Tolerance of Cascade Bioreactions via Adaptive Curvature Engineering for Epidermal Bioelectronics.
Wang, T, Lei, QL, Wang, M, Deng, G, Yang, L, Liu, X, Li, C, Wang, Q, Liu, Z, Wang, J, et al
Advanced materials (Deerfield Beach, Fla.). 2020;(22):e2000991
Abstract
Epidermal bioelectronics that can monitor human health status non-invasively and in real time are core to wearable healthcare equipment. Achieving mechanically tolerant surface bioreactions that convert biochemical information to detectable signals is crucial for obtaining high sensing fidelity. In this work, by combining simulations and experiments, a typical epidermal biosensor system is investigated based on a redox enzyme cascade reaction (RECR) comprising glucose oxidase/lactate oxidase enzymes and Prussian blue nanoparticles. Simulations reveal that strain-induced change in surface reactant flux is the key to the performance drop in traditional flat bioelectrodes. In contrast, wavy bioelectrodes capable of curvature adaptation maintain the reactant flux under strain, which preserves sensing fidelity. This rationale is experimentally proven by bioelectrodes with flat/wavy geometry under both static strain and dynamic stretching. When exposed to 50% strain, the signal fluctuations for wavy bioelectrodes are only 7.0% (4.9%) in detecting glucose (lactate), which are significantly lower than the 40.3% (51.8%) in flat bioelectrodes. Based on this wavy bioelectrode, a stable human epidermal metabolite biosensor insensitive to human gestures is further demonstrated. This mechanically tolerant biosensor based on adaptive curvature engineering provides a reliable bio/chemical-information monitoring platform for soft healthcare bioelectronics.
2.
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.