Improved bio-catalytic activity of Pseudomonas cepacia lipase immobilized on binary blend polymer matrix for kinetic resolution: Green metrics evaluation

Enzyme immobilization on a biocompatible, robust, reusable solid support is an effective strategy to augment the catalytic performance of free/native enzyme. Herein, a hybrid polymeric blend made up of biocompatible chitosan (CHI) and polyvinyl alcohol (PVA) carrier was successfully used to immobilize Pseudomonas cepacia lipase (PCL). The biocatalyst (PVA:CHI:PCL) was investigated for the kinetic resolution (KR) of racemic secondary alcohol 1-phenylethanol. Results showed that the developed biocatalyst offered significant biocatalytic activity for the kinetic resolution of 1-phenylethanol with conversion of 49% to the respective acetate of one isomer and excellent enantiomeric excess of substrate (ee_s:96%) as well as enantiomeric excess of product (ee_p:99%) and enantioselectivity (E). Further, synthesized binary blend biocatalyst offered excellent reusability up to six consecutive cycles with 41% conversion, 72% ee_s, and 98% ee_p at sixth recycle. Interestingly, immobilized biocatalyst displayed exceptionally enhanced biocatalytic activity as compared to free lipase PCL. Further study is extended to evaluate the green metrics involving determination of E-factor, atom efficiency, atom utilization and mass intensity. Results showed that use of the immobilized biocatalyst offered two-fold higher conversion than free lipase and better greener metrics as compared to that of free lipase.

Graphical abstract

Lipase PCL immobilized on PVA:CHI support was applied as a biocatalyst for kinetic resolution of (±)1-phenylethanol to offer 49% conversion with excellent enantiomeric excess of substrate (ee_s:96%), product (ee_p:99%) and enantioselectivity. The developed biocatalyst offered two-fold higher conversion, recyclability and better greener metrics in terms of E-factor, mass-intensity, and atom-efficiency than free lipase.