Ecofriendly and Conductive Corn-Cob-Based Biomass Driven from Aqueous Deep Eutectic Solvents: A Suitable Media for Enzyme Structure, Storage, and Activity at High Temperature

Production of biomaterials from lignocellulosic biomass waste is of prime importance for diverse applications. However, the use of harsh chemicals, extreme conditions, and tedious processes to convert it into useful materials are the major bottlenecks for its application. Herein, leftover waste of corn-cob biomass (CB) was converted into functional carbonaceous material via a solvothermal process using water in deep eutectic solvents (DESs) by employing two DESs namely, choline chloride-glycerol (ChCl-Gly) and ChCl-ethylene glycol (ChCl-EG). The synthesized CB-based solvothermal carbon materials, using CB-ChCl-Gly and CB-ChCl-EG, were characterized to verify incorporated morphological variations. The obtained results showed that the synthesized carbon materials were rich in oxygen functionality with a more porous, globular surface structure. Further, the detailed analysis of the feasibility of the synthesized biomaterials as biocompatible carriers for cytochrome-c (Cyt-c) was evaluated. The peroxidase-like activity was remarkably enhanced up to 1.5-fold compared to the native enzyme. Further, the biocompatibility of these synthesized carbon materials was validated using the Michaelis–Menten equation. Besides this, time- and temperature-dependent studies of Cyt-c after immobilization of these biomass-based carbon materials demonstrated preservation of structural integrity as well as improved enzymatic activity. Various biophysical techniques validated the improved secondary and tertiary structures of the enzymes after immobilization. The micrograph obtained using transmission electron microscopy (TEM) microscopy and hydrodynamic size (d_H) and zeta potential values measured using dynamic light scattering (DLS) showed successful protein immobilization on the synthesized carbon materials. Interestingly, the secondary structure of Cyt-c is maintained at higher temperatures in the presence of both CB-ChCl-EG and CB-ChCl-Gly carbon materials. Overall, this study elucidates a sustainable source and ecofriendly method of preparation of solvothermal carbon material and displays its beneficial influence on the activity and stability of Cyt-c. Remarkably, proving to be a protein-friendly host, CB will be helpful for long-term protein packing, which may provide a foundation for imaging modalities for the biomolecules with diverse industrial applications.