Wettability and surface charge of Si3N4-bioglass composites in contact with simulated physiological liquids.
Wettability and surface charge studies were performed on a novel Si3N4-30wt% bioglass biocomposite. Contact angle and surface tension variation with time were determined at 25 degrees C, respectively, by the sessile and pendant drop techniques, for distinct testing liquids: water, diiodomethane, simulated body fluid (SBF) and bovine serum albumin (BSA) dissolved in SBF solution. This biocomposite revealed a hydrophilic character (theta = 26.6 +/- 2.0 degrees) and a surface tension value (66.6 mJ m(-2)) comparatively higher than those of the most common bioceramics. An important characteristic is the high work of adhesion towards SBF + BSA (96.4 +/- 0.2mJ m(-2)) that was measured. The Si3N4-bioglass material is negatively surface charged above the pH(IEP) = 2.5 in aqueous SBF + BSA solution, as a result of the presence at the surface of unsaturated Si-O bonds and Si-OH groups. The very high negative zeta potential at pH approximately 7 (-58.6 +/- 5.5mV) influenced albumin adsorption and mechanisms are discussed in terms of entropy and enthalpy gains from conformational unfolding and cations coadsorption.
Amaral
M
M
Department of Ceramics and Glass Engineering, UIMC, University of Aveiro, Portugal.
Lopes
M A
MA
Santos
J D
JD
Silva
R F
RF
D005898:Glass; D006863:Hydrogen-Ion Concentration; D012710:Serum Albumin, Bovine / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry*; D013499:Surface Properties
D017655:Silicon Compounds; D012710:Serum Albumin, Bovine; C032734:silicon nitride