The Degradation and BMP Release Dynamics of Silica-Based Xerogels Modified by Adding Calcium and Magnesium or Sintering Process

Abstract

A new mesoporous silica xerogel used as biodegradable material was synthesized by improved sol-gel methods. The xerogel’s degradation character and property of releasing character for bone morphological protein (BMP)were modified by adding calcium (Ca) and phosphor (P) elements into pure silica xerogel, and uesing sintering processes, as well as adding magnesium (Mg) into silica xerogel. The differential thermal and thermogravimetric analysis (DTA-TG), X-Ray diffraction analysis(XRD), Fourier infrared spectrum analysis (FITR), N2 adsorption-desorption analysis, Scanning electron microscope(SEM) and Transmitting electron microscope (TEM) observation were used to measure the thermal effects, crystalline state, pore diameter and specific surface area, surface morphology and inner structure of the xerogels. The xerogel’s degradability and BMP release were studied by simulated body fluid (SBF) immersion. The results indicated that the synthesized xerogels were mesoporous structure with pore diameter around 3 nm and the big specific surface area about 1000 m2/g.They were non crystall with hydroxyl and micro-molecular silica-oxygen groups. Xerogels dried at low sintering temperature degraded completely in 42 days in bursting manner and degraded in linear curves with sintering temperature increased as well as adding calcium and magnesium into xerogels. The BMP release behaviour from the Mg-xerogel dried naturally was in controlled manner.