Minling Ding,Huizhe Niu,Nan Zhang,Tongtong Hou,Ping Guan,Xiaoling Hu
Here we report on a facile, rapid, selective, and stable electrochemical sensing platform for nicotinamide adenine dinucleotide (NADH) based on polythionine-methylene blue/electrochemically reduced graphene oxide modified glassy carbon electrode (PTH-MB DES -ERG/GCE). The ERG was directly formed on a glassy carbon electrode (ERG/GCE) through one-step electrochemical reduction of GO in PBS solution (10 mM, pH 7.4). In a PBS electrolyte, respectively, containing 50% (v/v) three different deep eutectic solvents (DES), thionine and methylene blue were polymerized on the surface of ERG/GCE. The electrochemical properties of the polymers polymerized in different electrolytes were investigated. The PTH-MB DES -ERG composite has a higher performance in the electrocatalytic oxidation of NADH than that of PTH-MB DES . The as-prepared PTH-MB DES -ERG/GCE demonstrated excellent direct electrocatalytic oxidation toward NADH, providing a favorable platform for electron transfer from NADH to the electrode. The sensor displayed a wide linear range from 1.52 μM to 3333.33 μM with a limit of detection of 0.51 nM. The interference from the ascorbic acid and uric acid was negligible. The prepared sensor was further tested for the determination of NADH in artificial urine samples, showing the PTH-MB DES -ERG/GCE formed by electropolymerization have promising biomedical applications.
A method is described for the rapid fluorometric determination of dopamine (DA) by using molybdenum disulfide quantum dots (MoS 2 QDs) that were fabricated via an ammonium hydroxide etching method. The probe has a fluorescence (with excitation/emission peaks at 267/380 nm) that is quenched by DA with high selectivity over various interferences. This is attributed to a reaction that occurs between DA and the molybdate ions in pH 9 solutions of MoS 2 QDs. The formation of organic molybdate complexes and of dopamine-quinone results in strong quenching of the fluorescence of the QDs which is due to both electron transfer and an inner filter effect. Under the optimum conditions, the assay works in the 0.1–100 μM DA concentration range, with two linear ranges and a 10 nM detection limit. The method was applied to the determination of DA in spiked artificial urine samples, where it gave recoveries ranging from 97.6 to 102.2%, demonstrating that the method a promising tool for rapid and selective detection of DA.
MoS 2 QDs are facilely synthesized via the etching effect of ammonium hydroxide for highly selective fluorometric detection of dopamine.
Panpan Hao,Rufeng Zhu,Yang Tao,Wei Jiang,Xue Liu,Yan Tan,Yuedan Wang,Dong Wang
Novel enhancement-mode organic electrochemical transistors (OECTs) have been prepared by poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) de-doped polyethylenimine on the multi-walled carbon nanotube-modified viscose yarn. The fabricated devices exhibit low power consumption with a high transconductance of 6.7 mS, rapid response time < 2 s, and excellent cyclic stability. In addition, the device has washing durability and bending and long-term stability suitable for wearable applications. Biosensors based on enhancement-mode OECTs for the selective detection of adrenaline and uric acid (UA) are developed by using molecularly imprinted polymer (MIP)-functionalized gate electrodes. The detection limits of adrenaline and UA analysis are as low as 1 pM, with the linear ranges of 0.5 pM to 10 μM and 1 pM to 1 mM, respectively. Moreover, the sensor based on enhancement-mode transistors can efficiently amplify the current signals according to the modulation of the gate voltage. The MIP-modified biosensor has high selectivity in the presence of interferents and desirable reproducibility. Additionally, due to the wearable nature of the developed biosensor, this sensing tool has the capability of being integrated with fabrics. Therefore, it has successfully been applied in textiles for the determination of adrenaline and UA in artificial urine samples. The excellent recoveries and rsds are 90.22–109.05% and 3.97–6.94%, respectively. Ultimately, these sensitive, low-power, wearable, and dual-analyte sensors help to develop non-laboratory tools for early disease diagnosis and clinical research.
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