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.
Department of Ceramics and Glass Engineering, UIMC, University of Aveiro, Portugal.
M
M
Amaral
M A
MA
Lopes
J D
JD
Santos
R F
RF
Silva
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