Silica nanoparticles with enlarged nanopore size for the loading and release of biological proteins

Silica nanoparticles (SNs) with a nanoporous structure are attractive for the delivery of biomolecules. This study developed a SNs-based protein delivery system with nanopore sizes large enough to uptake protein molecules. The use of trioctylmethylammonium bromide (TOMAB) as an auxiliary chemical facilitated a dramatic increase in pore size from 2.6 nm to 17.4 nm. The surface was highly negatively-charged with a zeta potential of approximately − 35 at pH 7. Positively-charged protein cytochrome C was encapsulated effectively within the large pore spaces of the SNs, with a protein loading capacity of almost 2-fold increase due to the pore size increase. The loaded protein exhibited sustained release for approximately one week with an initial burst in a day, suggesting the SNs tailored with enlarged nanopores should be useful for the delivery of large protein molecules for tissue regeneration.

► Silica nanoparticles with enlarged nanopores were prepared for the delivery of biological proteins.
► Protein uptake was significantly enhanced by the pore size control.
► Protein was released for up to about one week.