Trametes versicolor laccase oxidation of gallic acid toward a polyconjugated semiconducting material

• The controlled enzymatic polymerization of naturally existing gallic acid has been successfully achieved toward a polyconjugated structure.
• Laccase from Trametes versicolor probed successful for this synthesis.
• The novel material displays semiconductivity owing to its polyconjugated structure.
• The novel material is bioresourceable.

This study is concerned with the successful synthesis of a semiconducting polyphenol in high yield (82%) from Trametes versicolor laccase-mediated oxidative polymerization of the naturally abundant gallic acid. The determined KM was 0.418 mM, thus showing high affinity of this enzyme for the substrate. The polymer can be solubilized in water up to 150 mg mL−1, whereas it presents poor solubility in organic solvents. The molecular structure presented phenylene propagation which allowed for a maximum conductivity in solid state of 10−4 S m−1 with a band gap (Eg) of 2.41 eV. In addition, a growing absorption peak at 450 nm monitored by UV-spectra was observed during polymerization. Cyclic voltammetry studies in aqueous solution of the polymers displayed a cathodic wave around 0.35 V vs Ag/Ag+ and two anodic waves between 0.4 and 0.8 V vs Ag/Ag+ at any scan rate for all samples, interestingly, the peak current of the waves increased with the increase of the scan rate.

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