This work reports an amperometric enzyme-electrode prepared with glucose oxidase, which have been immobilized by a cross-linking step with glutaraldehyde in a mixture containing albumin and a novel carbon nanotubes-mucin composite (CNT-muc). The obtained hydrogel matrix was trapped between two polycarbonate membranes and then fixed at the surface of a Pt working electrode. The developed biosensor was optimized by evaluating different compositions and the analytical properties of an enzymatic matrix with CNT-muc. Then, the performance of the resulting enzymatic matrix was evaluated for direct glucose quantification in human blood plasma. The novel CNT-muc composite provided a sensitivity of 0.44 ± 0.01 mA M and a response time of 28 ± 2 s. These values were respectively 20% higher and 40% shorter than those obtained with a sandwich-type biosensor prepared without CNT. Additionally, CNT-muc based biosensor exhibited more than 3 orders of magnitude of linear dynamic calibration range and a detection limit of 3 μM. The short-term and long-term stabilities of the biosensors were also examined and excellent results were obtained through successive experiments performed within the first 60 days from their preparation. Finally, the storage stability was remarkable during the first 300 days.
This work reports the advantages of carbon paste electrodes modified with electrogenerated magnetite nanoparticles. The nanoparticles present catalytic activity towards hydrogen peroxide reduction. The incorporation of glucose oxidase (GOx) and magnetite in a carbon paste matrix have made possible the development of an efficient glucose biosensor. The effect of the amount of GOx and magnetite present in the composite on the response of the biosensor was critically evaluated. The biosensors demonstrated to be highly selective, with negligible interference of ascorbic acid and uric acid. The proposed biosensor was challenged with human blood serum demonstrating an excellent correlation with the spectrophotometric method.
This work reports the effect of the incorporation of different proteins within carbon paste electrodes (CPE) modified with electrochemically synthesized magnetite nanoparticles (20 nm) on the electrochemical response towards hydrogen peroxide. Scanning electron microscopy images reveal that the proteins produce a more efficient dispersion of the nanoparticles within the composite. When CPE is modified with 5.0 % w/w magnetite and 5.0 % w/w albumin the sensitivity for hydrogen peroxide at −0.100 V is enhanced 40 times and the charge transfer resistance significantly decreases. The increase in sensitivity and the decrease in Rct was dependent on the nature of the protein.
This work reports the analytical applications of a graphene paste electrode (GrPE) for the quantification of dopamine, ethanol and phenolic compounds. Dopamine was detected by differential pulse voltammetry‐adsorptive stripping with medium exchange at submicromolar levels even in the presence of high excess of ascorbic acid and serotonin. The electrocatalytic activity of graphene towards the oxidation of NADH and the reduction of quinones allowed the sensitive amperometric determination of ethanol and phenols using GrPE modified with alcohol dehydrogenase/NAD+ or polyphenol oxidase, respectively, with successful applications in real samples like alcoholic beverages and tea.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.