In Vitro and In Vivo Investigation of the Potential of Amorphous Microporous Silica as a Protein Delivery Vehicle

Delivering growth factors (GFs) at bone/implant interface needs to be optimized to achieve faster osseointegration. Amorphous microporous silica (AMS) has a potential to be used as a carrier and delivery platform for GFs. In this work, adsorption (loading) and release (delivery) mechanism of a model protein, bovine serum albumin (BSA), from AMS was investigatedin vitroas well asin vivo. In general, strong BSA adsorption to AMS was observed. The interaction was stronger at lower pH owing to favorable electrostatic interaction.In vitroevaluation of BSA release revealed a peculiar release profile, involving a burst release followed by a 6 h period without appreciable BSA release and a further slower release later. Experimental data supporting this observation are discussed. Apart from understanding protein/biomaterial (BSA/AMS) interaction, determination ofin vivoprotein release is an essential aspect of the evaluation of a protein delivery system. In this regard micropositron emission tomography (μ-PET) was used in an exploratory experiment to determinein vivoBSA release profile from AMS. Results suggest strongerin vivoretention of BSA when adsorbed on AMS. This study highlights the possible use of AMS as a controlled protein delivery platform which may facilitate osseointegration.