A novel hybrid material with calcium and strontium release capability

Abstract

The preparation of PDMS-TEOS-CaO hybrid materials by sol-gel techniques has been widely described in previous works. Calcium nitrate is the most common source of calcium used in these preparations. However, to remove possible toxic nitrate by-products a thermal treatment is necessary at temperatures above 500 ºC, which leads to the degradation of the polymeric components of the hybrids. Strontium has already shown some promising results in the therapeutic area, being used in cases of osteoporosis and low bone density. In this study a new potential bioactive hybrid material was prepared, by sol-gel techniques, using calcium acetate as a novel calcium source. Also, for the first time, incorporation of strontium in a PDMS-TEOS hybrid system was evaluated. Samples were characterized before and after immersion in Kokubo's Simulated Body Fluid (SBF) by SEM, EDS, ICP and FT-IR spectroscopy . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 isabelmsalvado@ua.pt AbstractThe preparation of PDMS-TEOS-CaO hybrid materials by sol-gel techniques has been widely described in previous works. Calcium nitrate is the most common source of calcium used in these preparations. However, to remove possible toxic nitrate by-products a thermal treatment is necessary at temperatures above 500 ºC, which leads to the degradation of the polymeric components of the hybrids. Strontium has already shown some promising results in the therapeutic area, being used in cases of osteoporosis and low bone density. In this study a new potential bioactive hybrid material was prepared, by sol-gel techniques, using calcium acetate as a novel calcium source. Also, for the first time, incorporation of strontium in a PDMS-TEOS hybrid system was evaluated. Samples were characterized before and after immersion in Kokubo's Simulated Body Fluid (SBF) by SEM, EDS, ICP and FT-IR spectroscopy.

PDMS-SiO2-TiO2-CaO hybrid materials – Cytocompatibility and nanoscale surface features

“…Other calcium sources were tried, such as calcium chloride or calcium methoxyethoxide, but some processing related problems still persisted [8]. In a previous work our group used calcium acetate as an alternative calcium source for PDMS-SiO 2 based hybrids and produced a potential bioactive material [16], as suggested from immersion tests in a synthetic physiological fluid. Although the PDMS-SiO 2 -CaO hybrid system has been appointed as a potentially promising system for biomedical applications in bone substitutes, no information exists in the literature about its cytocompatibility in the presence of osteoblastic cells.…”

“…For this, two PDMS-SiO 2 -TiO 2 -CaO porous hybrid materials were prepared with the same amounts of precursors and solvents, but using two different approaches for the sol-gel procedure based on the authors' previous works [12,16,17]. The …”

A biocompatible hybrid material with simultaneous calcium and strontium release capability for bone tissue repair

“…Both exhibit the characteristic bands assigned to SiO 2 structural units, PDMS backbone, and to PDMS-SiO 2 hybrid bonds [5,23,24].…”

“…Calcium has been usually added to the sol-gel process using its nitrate form with a decomposition temperature higher than the degradation temperature of PDMS [4]. Since this problem was solved with the use of calcium acetate as a precursor [5], new possibilities opened.…”

“…Based on authors' previous findings the addition of titanium is justified by its capability to condition the sol-gel chemistry of the system PDMS-SiO 2 , allowing the modulation of the final microstructure, besides the fact that titanium can also increase the bioactivity, due to surface Ti-OH groups [15]. To avoid the use of nitrates, calcium and strontium were added using the respective acetates as sources, according to a sol-gel technique already described in a previous work [5]. The materials' structures and microstructures were analyzed by Fourier Transform Infrared Spectrometry (FT-IR), solid state Nuclear Magnetic Resonance (NMR) techniques, Smallangle X-ray Scattering (SAXS) and Scanning Electron Microscopy (SEM).…”