Surface Functionalization of Bacterial Cellulose Nanoparticles for Sustainable Nanomedicine

Sustainable nanomedicine is an emerging field of nano-based therapeutics to combat the environmental impact of current synthetic nanomaterials. There is a field-wide need to improve formulation processes that reduce waste generated in the nanomedicine industry. Sustainable nanomedicine uses green engineering, a technique implemented in processing to reduce extensive waste generation through the synthesis and formulation of biologically derived nanomaterials to create commercially scalable, waste-free products. Biologically sourced nanomaterials such as polysaccharides, have gained interest for nanomedicine use and many are already FDA approved in the pharmaceutical, food and beverage, and cosmetic industries. We have recently developed bacterial cellulose nanoparticles (BCNPs) for sustainable drug delivery. The development of BCNPs was motivated by a synthesis method that has reduced environmental impact, an overall eco-friendly life cycle, compared to synthetic nanomaterials. BCNPs were formulated via nanoprecipitation using dissolved bacterial cellulose in dimethylacetamide and lithium chloride and surfactant solution. The particle size of BCNPs were 100-200 nm with a polydispersity index (<0.3, PDI), near neutral or slightly negative zeta-potential, and a primarily amorphous morphology, desired parameters for nano-drug delivery. BCNPs were characterized by electron microscopy and zeta potential analyzer, and the PDI was calculated. To advance the use of BCNPs, we applied surface functionalizations such as methylation, acetylation, and amination to tune the surface functionality and charge density. Commercially manufactured alpha cellulose was first surface modified as a control via methylation and acetylation to yield a greater hydrophobic material, while amination was used to yield a more hydrophilic material. After validating the functionalization for positive and negatively charged cellulose matrices with Fourier transform infrared spectroscopy and X-ray crystallography, we next applied the same functionalization methods to BC pellicle, prior to nanoparticle formulation. Our results establish a tunable and sustainably derived platform in nanomedicine for targeted drug delivery applications. Functionalized BCNPs can open opportunities for other utilizations and an eco-friendlier way to produce therapeutics using green engineering.