One pot preparation of a hybrid chemoenzymatic heterogeneous catalyst by spray drying for enantioselective hydroxylation reactions

Details

Supervisors

Debecker, Damien P. ; Kinnaer, Marty

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

enThe pharmaceutical industry is a major contributor to global greenhouse gas emissions, necessitating the development of more sustainable and milder production routes for active pharmaceutical ingredients (API). Unspecific peroxygenases (UPOs) have emerged as promising biocatalysts for oxyfunctionalization reactions, offering high catalytic efficiency under mild conditions and excellent (enantio)selectivity. However, their industrial application is limited by their sensitivity to H₂O₂ and by the lack of reusability in systems relying on free UPO. Immobilization of the enzymes provides a potential solution to both issues: colocalizing UPO with a heterogeneous catalyst for the in situ generation of H₂O₂ could allow the enzyme to operate with low H₂O₂ concentrations while enabling catalyst reusability. This master thesis aims to synthesize a heterogeneous chemoenzymatic hybrid catalyst (HCEHC) made of UPO and gold-palladium nanoparticles supported on TiO2. Owing to its scalability, ease of implementation and rapid processing, we chose to work via a one-pot spray-drying approach for the preparation of these multifunctional materials. To protect UPO from the harsh conditions associated with spray-drying, two protection strategies were investigated: enzyme polyelectrolyte complexes (EPCs) and cross-linked enzyme aggregates (CLEAs). This work assesses the viability of these protection methods to produce viable hybrid catalysts. While EPC-based hybrid catalysts did not yield satisfactory results, the initial CLEAs-based hybrid catalysts retained enzymatic activity after spray-drying, with no detectable leaching, but poor reusability. The influence of the precipitating agent during the preparation of CLEAs was investigated, leading to the synthesis of a hybrid catalyst exhibiting improved recyclability, though at the expense of reduced productivity.