Protein interactions with nanoporous sol–gel derived bioactive glasses

Sol–gel derived bioactive glasses are excellent candidates for bone regenerative implant materials as they bond with bone, stimulate bone growth and degrade in the body. Their interactions with proteins are critical to understanding their performance after implantation. This study focuses on the interactions between fibrinogen and sol–gel glass particles of the 70S30C (70 mol.% SiO2, 30 mol.% CaO composition). Sol–gel silica and melt-derived Bioglass® were also used for comparison. Fibrinogen penetration into the nanoporous glasses was observed by live tracking the fluorescent-labelled fibrinogen with confocal microscopy. The effect of pore size on protein penetration was investigated. Nanoporous networks with modal pore diameters larger than 6 nm were accessible to fibrinogen. When the modal nanopore diameter was decreased to 2 nm or less, the penetration of fibrinogen was inhibited. The surface properties of the glasses, which can be modulated by media pH, glass composition and final stabilisation temperature in the sol–gel process, have effects on fibrinogen adsorption via long-range Coulombic forces before the adsorption and via short-range interactions such as hydrogen bonding after the adsorption.