Rotavirus VP6 protein as a bio-electrochemical scaffold: Molecular dynamics and experimental electrochemistry.

This paper reports a theoretical and experimental investigation on the recombinant protein rotavirus VP6 as a bioelectrochemical interface. Our motivation arises from the highly active zones of VP6 which can interact with biological structures and metals, as well as its useful features such as self-assembly, polymorphism, and active surface charge. A molecular simulation study was performed to analyze the charge transfer properties of theVP6 trimer under an applied electric field. The electrostatic properties were evaluated via the nonlinear second-order Poisson-Boltzmann equation, using finite element methods based on parameter discretization and calculation of solute/solvent interaction forces, which account for mean-field screening effects. The electrochemical study validated the theoretical predictions for VP6 in their different assemblies (trimers and nanotubes) when they are used as electrodes in 10 mM K3[Fe(CN)6], 1 M KCl. Applying a potential sweep promotes charge transfer, facilitates redox activity of the ferricyanide ion. Furthermore, protein assemblies decreased electrode electrical resistance and enabled gold particle electrodeposition on the protein VP6. These results suggest that VP6 is a promising conductive biomaterial that promotes charge transfer of redox probes and could be used as a new scaffold to create bio-electrochemical interfaces.

Gold nanoparticles/4-aminothiophenol interfaces for direct electron transfer of horseradish peroxidase: Enzymatic orientation and modulation of sensitivity towards hydrogen peroxide detection.

Hydrogen peroxide electrochemical detection by horseradish peroxidase has been widely studied. The use of gold nanoparticles to prepare electrode/enzyme bioconjugates has attracted attention due to their catalytic properties. In this work, it is reported the use of gold nanoparticles and 4-aminothiophenol as a scaffold to obtain a suitable matrix for enzyme bioconjugation with horseradish peroxidase. A critical factor in biosensors design and development is the enzymatic electrochemical activity understanding. Comparison of voltammetric studies of the heme prosthetic group showed a reversible electrochemical behavior when the enzymes were immobilized in a well-dispersed gold deposit; on the other hand, a discrete redox response was observed on a randomly deposited gold electrode. These results show that the distance between enzymes is essential. Hydrogen peroxide catalysis and the enzymatic behavior were analyzed considering two types of nanoparticles dispositions. The catalytic behavior observed in the well-dispersed nanoparticles configuration suggests a preserved enzyme folding, a decrease of steric impediments, and appears to be a better immobilization strategy. In contrast, the randomly electrodeposited gold electrode decreased the enzyme orientation and the electrochemical activity. The advantages of this methodology are the electrode fabrication affordable cost and the enzymatic direct electron transfer response improvement.