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Laccase-assisted assembling of hybrid biopolymer-silver nanoparticles and cork matrices into an antimicrobial material with potential for water remediation is herein described. Amino-functional biopolymers were first used as doping agents to stabilize concentrated colloidal dispersions of silver nanoparticles (AgNP), additionally providing the particles with functionalities for covalent immobilization onto cork to impart a durable antibacterial effect. The solvent-free AgNP synthesis by chemical reduction was carried out in the presence of chitosan (CS) or 6-deoxy-6-(ω-aminoethyl) aminocellulose (AC), leading to simultaneous AgNP biofunctionalization. This approach resulted in concentrated hybrid NP dispersion stable to aggregation and with hydrodynamic radius of particles of about 250 nm. Moreover, laccase enabled coupling between the phenolic groups in cork and amino moieties in the biopolymer-doped AgNP for permanent modification of the material. The antibacterial efficiency of the functionalized cork matrices, aimed as adsorbents for wastewater treatment, was evaluated against Escherichia coli and Staphylococcus aureus during 5 days in conditions mimicking those in constructed wetlands. Both intrinsically antimicrobial CS and AC contributed to the bactericidal effect of the enzymatically grafted on cork AgNP. In contrast, unmodified AgNP were easily washed off from the material, confirming that the biopolymers potentiated a durable antibacterial functionalization of the cork matrices.

The effect of the oxidation degree of multiwalled carbon nanotubes (MWCNTs) for the detection of NADH was evaluated in this paper. MWCNTs were oxidized by microwave‐assisted sulfonitic treatment at different times (5, 10, 15, and 30 min) and deposited onto a graphite screen printed electrodes. Oxidized MWCNTs were characterized and the electrochemical performance evaluated. The best sensor in terms of sensitivity and stability was obtained after 15 minutes of oxidation (SPE/CNT15). A significant reduction of the NADH oxidation potential was recorded for oxidized MWCNTs compared with unmodified MWCNTs (0.270 V and 0.500 V, respectively vs. Ag/AgCl pseudo reference electrode), increasing the selectivity of the system. Chronoamperometric calibration curves carried out applying a potential of 0.3 V for 1 min were linear in the 4–35 μM range of NADH. A limit of detection of 1 μM was achieved with negligible surface fouling (three consecutive calibration curves, 30 total measurements: slope decrease 5.9 %). Inter electrode reproducibility (n=13) was good resulting in RSD of 15.2 % and 5.0 % for the peak intensity and the oxidation potential, respectively. Quantification of glucose in white wine samples was carried out to demonstrate the ability of the NADH sensor to work in real samples. A good correlation with a spectrophotometric kit for the glucose quantification was achieved.