Sustainable Platform for Biologics Delivery from Cellulose Microcrystals

Cellulose-based materials are promising biocarriers owing to their inherent biodegradability, biocompatibility, and low toxicity. This study demonstrates the potential of microcrystalline cellulose (MCC), synthesized through an acid hydrolysis of cotton using H₂SO₄:H₂O₂ (3:1), followed by a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation process, as a biologics carrier. Hydrolysis time affected the MCC size and morphology, while oxidation introduced carboxyl groups for functionalization. Chitosan (CHI) was used to decorate the MCC, enhancing its protein-binding ability. The biologic loading capacity of both synthesized MCC and CHI-decorated MCC (MCC/CHI) was evaluated using bovine serum albumin (BSA) as a model protein. Results indicated that MCC/CHI exhibited a more than 22% increase in BSA loading compared with unmodified MCC. Furthermore, the influence of phosphate on BSA attached to both the MCC and MCC/CHI was investigated. It was observed that the phosphate solution aided in maintaining the BSA configuration, irrespective of pH variations in the solution. As a result, despite the difference in surface properties, a similar pattern of BSA release was observed for both the MCC and MCC/CHI. These findings highlight the potential of functionalized MCC for a biologics delivery system in the future.