In this study, yeast strains were screened and immobilized in a form preserving the multifaceted biocatalytic activity. Im-mobilization of the silica-supported whole-cells of various yeasts – such as Lodderomyces elongisporus, Pichia carsonii, Candida norvegica and Debaryomyces fabryi – by sol-gel entrapment resulted in easy-to-handle biocatalysts that mediated efficiently different types of synthetic reactions. In the present study, the enantiotope selective reduction of prochiral ke-tones 1a-d and the acyloin condensation of benzaldehyde 3 were studied representing two remarkably diverse types of bio-transformation. The yeast cell biocatalysts – in the presence of fresh or recovered NADH cofactor – could be applied for continuous-flow bioreduction of ketones 1a,b with moderate to good yields (20 to 92%) and excellent enantiomeric purity (>99%). Immobilized L. elongisporus and P. carsonii cells could also mediate acyloin condensation of benzaldehyde 3 in batch as well as in continuous-flow mode. The switchable biocatalytic activity of the immobilized yeast cells was demon-strated by consecutive biotransformations under continuous-flow conditions involving reduction of phenylacetone 1a to (S)-phenylpropane-2-ol (S)-2a first, followed by conversion of benzaldehyde 3 to (R)-1-hydroxy-1-phenylpropan-2-one (R)-4 and reduction of 1a to (S)-2a again by using the same packed bed bioreactor.

An easy to use method combining the selectivity of metal chelate affinity binding with strong covalent linking was developed for immobilization of non‐specific acid phosphatases bearing a His‐tag from crude cell lysate. Silica nanoparticles were grafted with aminopropyl functions which were partially transformed further with EDTA dianhydride to chelators. The heterofunctionalized nanoparticles charged with Ni²⁺ as the most appropriate metal ion were applied as support. First, the His‐tagged phosphatases were selectively bound to the metal‐chelate functions of the support. Then, the enzyme‐charged silica nanoparticles were further stabilized by forming a covalent linkage between nucleophilic moieties at the enzyme surface and free amino groups of the support using neopentylglycol diglycidylether as the most effective bifunctional linking agent. The phosphatase biocatalysts obtained by this method exhibited better phosphate transfer activity with a range of alcohols and PP_i as phosphate donor in aqueous medium applying batch and continuous‐flow modes than the ones immobilized on conventional supports. Furthermore, this novel strategy opens up novel possibility for efficient immobilization of other His‐tagged recombinant enzymes.

This article overviews the numerous immobilization methods available for various biocatalysts such as whole-cells, cell fragments, lysates or enzymes which do not require preliminary enzyme purification and introduces an advanced approach avoiding the costly and time consuming downstream processes required by immobilization of purified enzyme-based biocatalysts (such as enzyme purification by chromatographic methods and dialysis). Our approach is based on silica shell coated magnetic nanoparticles as solid carriers decorated with mixed functions having either coordinative binding ability (a metal ion complexed by a chelator anchored to the surface) or covalent bond-forming ability (an epoxide attached to the surface via a proper linker) enabling a single operation enrichment and immobilization of a recombinant phenylalanine ammonia-lyase from parsley fused to a polyhistidine affinity tag.

Biomimetic oxidation of drugs catalyzed by metalloporphyrins can be a novel and promising way for the effective and sustainable synthesis of drug metabolites. The immobilization of 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)iron(II) porphyrin (FeTPFP) and 5,10,15,20-tetrakis-(4-sulfonatophenyl)iron(II) porphyrin (FeTSPP) via stable covalent or rapid ionic binding on aminopropyl-functionalized magnetic nanoparticles (MNPs-NH₂) were developed. These immobilized catalysts could be efficiently applied for the synthesis of new pharmaceutically active derivatives and liver related phase I oxidative major metabolite of an antiarrhythmic drug, amiodarone integrated in a continuous-flow magnetic chip reactor (Magnechip).