AUTHOR=Magalhães Flávia F. , Pereira Ana F. , Freire Mara G. , Tavares Ana P. M. 

TITLE=New liquid supports in the development of integrated platforms for the reuse of oxidative enzymes and polydopamine production

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.1037322

DOI=10.3389/fbioe.2022.1037322

ISSN=2296-4185

ABSTRACT=Polydopamine (PDA), a bioinspired polymer from mussel adhesive proteins has attracted impressive attention as a novel coating for (nano)materials with an adequate conformal layer and adjustable thickness. Currently, PDA is obtained from dopamine chemical oxidation under alkaline conditions, limiting its use in materials sensible to alkaline environments. Envisaging a widespread use of PDA, the polymerization of dopamine by enzymatic catalysis allows the dopamine polymerization in a large range of pHs, overcoming thus the limitations of the conventional chemical oxidation. Moreover, the conventional method of polymerization is a time-consuming process and produces PDA films with poor stability, which restricts its applications. On the other hand, the main bottleneck of enzyme-based biocatalytic processes is the high cost of the single use of the enzyme. In this work, laccase was used to catalyse the dopamine polymerization. To improve its performance, a liquid support for integrating the immobilization of laccase and its reuse together with the PDA production and recovery was developed using aqueous biphasic systems (ABS). Firstly, dopamine polymerization by laccase was optimized in terms of pH, temperature and initial dopamine concentration. It was demonstrated that the highest enzymatic polymerization of dopamine was achieved at pH 5.5, 30°C and 2 mg mL-1 of dopamine. Then, several ABS composed of polymers, salts and ionic liquids were evaluated to optimize the laccase immobilization in one phase while PDA is recovered in the opposite phase. The most promising ABS allowing the separation of laccase from the reaction product is composed of polypropylene glycol (400 g mol-1) and K2HPO4. The polymerization of dopamine in ABS leads to a remarkable improvement of polymerization of 3.9-fold in comparison to the conventional chemical PDA polymerization. The phase containing the immobilized laccase was reused for four consecutive reaction cycles, with a relative polymerization of 68.9% in the last cycle. These results proved that ABS are a promising approach to create a liquid support for enzyme immobilization allowing the process intensification. The use of biocatalysts in ABS emerges as sustainable and alternative platforms from environmental and techno-economic points of view.