Synthesis of nanostructured silica particles for controlled release of ascorbic acid: Microstructure features and in...

To date, the long term stability of ascorbic acid (AA) under physiological conditions represents a major issue for wound healing and tissue regeneration applications. In this study, ascorbyl phosphate (AP) was loaded into silica nanoparticles (SiNPs) through a simple one step procedure, in which spherical shaped porous SiNPs were obtained via hydrolysis/condensation of tetraethylorthosilicate (TEOS) in the presence of bicarbonate salt and ammonia. The as-prepared SiNPs were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier Transformer Infrared Spectrophotometer (FTIR). Incorporation of bicarbonate salt resulted in the formation of spherical SiNPs with an average diameter of 460 ± 89 nm, while further increase of bicarbonate salt led to the formation of silica sheet-like structures. The AP-loaded SiNPs exhibited high loading efficiency from 92.3- 81.5%, according to AP content and sustained release over 3 days. According to cell viability assay, the obtained AP-enriched SiNPS showed no toxicity and supportive effect to the proliferation of human skin fibroblast cells (HSF) at a concentration less than 200 µg mL^-1 . Moreover, it was observed that the wound closure percentage (%) after 24 h was also shown to increase to 74.1 ± 3.1% for 20AP-loaded SiNPs compared to control samples (50.1 ± 1.8%). The obtained results clearly demonstrated that the developed SiNPs formulation exhibits optimal microstructure features to maintain a sustained release of ascorbic acid AA at wound bed for the healing of skin tissue, including acute and chronic wounds.