A new strategy for oriented covalent immobilization of Trametes hirsuta laccase on gold electrodes is presented. The strategy is based on the gold surface modification with a mixed monolayer of an aromatic diazonium salt derivative and 6-mercapto-1-hexanol for further use as scaffold for the enzyme's covalent linkage. This strategy offers a variety of advantages such as high stability and laccase-friendly support morphology, which turns it into a suitable metal-enzyme interface. Conditions aiming at optimum orientation for direct electron transfer (DET) via the T1 copper site were studied.Current density values up to 40 µA·cm -2 were measured for the electrocatalytic reduction of O 2 in absence of redox mediators. This strategy is a big step forward in the development of laccase-modified gold electrodes for bioelectrocatalytic reduction of O 2 .

Macroporous poly(styrene-co-divinylbenzene) microparticles from reactive mixtures with various divinylbenzene and diluent contents have been synthesized. n-Heptane, which is a poor solvent for the copolymer, was used as diluent of the organic phase during the polymerization to obtain a high percentage of meso- and macropores, which are the most useful pores in the adsorption of macromolecules of medium and large sizes, such as proteins. The research was planned through a factorial design of experiments in an attempt to determine a quantitative relationship between the pore characteristics of the microparticles obtained and the concentration of the divinylbenzene and of the diluent used in the reactive mixture. The nitrogen adsorption−desorption isotherm and the curve of mercury intrusion for each type of microparticle were obtained, and the BET-specific surface areas and the volumes of macro-, meso-, and micropores were determined. Finally, empirical models correlating the synthesis conditions with the BET-specific surface area and the volumes of the micro-, meso-, and macropores were calculated; it was observed that the higher the divinylbenzene concentration in the monomeric mixture, the higher the volumes of micro- and mesopores and the larger the BET-specific surface area. It was also concluded that the higher the amount of diluent, the higher the volumes of meso- and macropores. Within the scope of the work, these models permit the synthesis of adsorbents with predetermined pore properties.

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The adsorption properties of macroporous polymeric microparticles are dependent on their porous structure, which, in turn, is dependent on the synthesis conditions of the adsorbent material. In the present work, we have investigated whether it is feasible to find a quantitative relationship between the synthesis conditions of macroporous poly(styrene-co-divinylbenzene) adsorbent microparticles and their behavior in the adsorption of a protein of intermediate size. For this purpose, 10 types of such microparticles were synthesized from reactive mixtures with different divinylbenzene (cross-linker) and n-heptane (diluent) contents, and the equilibrium isotherms and adsorption kinetics of a model protein (the bovine serum albumin (BSA) protein) were studied. The results allowed us to determine some quantitative relationships that, within the limits of this research, permit the synthesis of adsorbents with predetermined adsorption properties. Thus, the model obtained, relating the synthesis conditions of the adsorbents to the adsorption equilibrium, reveals that the higher the divinylbenzene concentration and the higher the diluent content, the higher the maximum adsorption capacity of the adsorbents for this protein. With regard to adsorption kinetics, the fastest adsorption was achieved with the lowest divinylbenzene concentration and the highest diluent concentration.