Effect of net surface charge on physical properties of the cellulose nanoparticles and their efficacy for oral protein delivery

• CMC–QC nanoparticles could load both positively and negatively charged proteins.
• Encapsulation was efficient by loading protein on oppositely charged nanoparticles.
• Proteins could be sustainably released and no protein denaturation was detected.
• Both positively and negatively charged nanoparticles exhibited low cytotoxicity.
• Both positively and negatively charged nanoparticles were uptake by Caco-2 cells.

Both net positively and negatively charged cellulose-based nanoparticles were prepared from oppositely charged carboxymethylcellulose (CMC) and quaternized cellulose (QC). Effect of surface charge on efficacy of cellulose nanoparticles for delivering both positively and negatively charged proteins was investigated. Lysozyme (LYS) and bovine serum albumin (BSA), which possess positive and negative charge at physiological pH respectively, were used as models. The results revealed that high encapsulation efficiency (67.7% and 85.1%) could be achieved when negatively charged protein was encapsulated in positively charged nanoparticles, or positively charged protein was encapsulated in negatively charged nanoparticles. Proteins encapsulated in optimal cellulose nanoparticles could be sustainably released and no obvious protein denaturation was detected. Both net positively and negatively charged nanoparticles exhibited low cytotoxicity due to cellulose's good biocompatibility. Not only net positively charged nanoparticles demonstrated high cellular uptake efficiency, but also net negatively charged nanoparticles showed somewhat efficient cellular uptake.

The surface charge played an important role in cellular uptake of cellulose nanoparticles. The positively charged protein-encapsulated nanoparticles were more efficiently internalized; the negatively charged protein-encapsulated nanoparticles also exhibited a somewhat efficient cellular uptake, which might be due to the biologically adhesive polysaccharide coating. Schematic representation and cellular uptake of cellulose nanoparticles.Figure optionsDownload as PowerPoint slide