Methodologies for “Wiring” Redox Proteins/Enzymes to Electrode Surfaces

The immobilization of redox proteins or enzymes onto conductive surfaces has application in the analysis of biological processes, the fabrication of biosensors, and in the development of green technologies and biochemical synthetic approaches. This review evaluates the methods through which redox proteins can be attached to electrode surfaces in a “wired” configuration, that is, one that facilitates direct electron transfer. The feasibility of simple electroactive adsorption onto a range of electrode surfaces is illustrated, with a highlight on the recent advances that have been achieved in biotechnological device construction using carbon materials and metal oxides. The covalent crosslinking strategies commonly used for the modification and biofunctionalization of electrode surfaces are also evaluated. Recent innovations in harnessing chemical biology methods for electrically wiring redox biology to surfaces are emphasized

Colloidal Nanoparticles as a Wireless Booster for Electroenzymatic Reactions

The colloidal nanoparticles as a wireless booster for electroenzymatic reactions were discussed, where nPt was used in a colloidal form dispersed homogeneously in a reaction medium to enhance the yield of a model enzymatic reaction. NADH regeneration required that the enzymatic turnover was boosted by the wireless catalyst or mediator. Enzyme metalyzed reactions have emerged as an alternative strategy to conventional chemical synthesis for producing pharmaceuticals cosmetics and even bulk chemicals. The study has tested several metal nanoparticles such as palladium and gold, resulting for nPd and nAu were disappointing in terms of electrocatalytlc power to regenerate NADH when compared with that of nPt. The work opened a new electrochemical application of nanoparticles that are not hound to electrodes hut dispersed in reaction media, including the electroenzymatic conversion shown in the work.close11

In-situ production of Histamine-imprinted polymeric materials for electrochemical monitoring of fish

Histamine (HIS) is a major public health problem due to its toxic properties. High levels can cause a chronic toxicity as poisoning and can be used as a signal of food hygiene. Thus, a new electrochemical sensor for HIS detection in fish is presented herein, prepared by tailoring a molecularly imprinted polymer (MIP) sensing material on a gold screen-printed electrode (Au-SPEs), in which the polymeric film was generated in-situ. This film was obtained by electropolymerizing aniline under conditions that preserved the chemical structure of HIS. Raman spectroscopy followed the chemical changes occurring at each stage of the electrode modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]4/[Fe(CN)6]3, by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS was also used to calibrate the sensor, being the standard solutions prepared under different background media (electrolyte or a blank sample of fish extract). The device displayed a linear response from 500nM to 1mM, with a limit of detection of 210nM, and a selective behaviour against tyramine, another amine related to fish degradation. The sensing system was further employed to monitor the HIS content in samples in different time points of storage at ambient temperature. The obtained results were in agreement with the ELISA method, while offering more reproducible data. In general, the optimized sensor allowed reproducible and accurate analysis of fish samples subject to degradation and was completely assembled in-situ, in a very simple and straightforward approach. The device is low cost and suitable for further adaptation to on-site analysis, as required in food control.The authors acknowledge national funding to the National Foundation for Science and Technology (FCT), I.P., and European funding to FEDER (European Funding or Regional Development), via COMPETE2020 – POCI (operational program for internationalization and competitiveness), through projects PTDC/MAR-IO/6044/2014 and PTDC/AAG-TEC/5400/2014.info:eu-repo/semantics/publishedVersio