Abstract
Silica/biopolymer hydrogel-based materials constitute very attractive platforms for various emerging biomedical applications, particularly for bone repair. The incorporation of calcium phosphates in the hybrid network allows for designing implants with interesting biological properties. Here, we introduce a synthesis procedure for obtaining silica–chitosan (CS)–tricalcium phosphate (TCP) xerogels, with CS nominal content varying from 4 to 40 wt.% and 10 to 20 wt.% TCP. Samples were obtained using the sol-gel process assisted with ultrasound probe, and the influence of ethanol or water as washing solvents on surface area, micro- and mesopore volume, and average pore size were examined in order to optimize their textural properties. Three washing solutions with different soaking conditions were tested: 1 or 7 days in absolute ethanol and 30 days in distilled water, resulting in E1, E7, and W30 washing series, respectively. Soaked samples were eventually dried by evaporative drying at air ambient pressure, and the formation of interpenetrated hybrid structures was suggested by Fourier transformed infrared (FTIR) spectroscopy. In addition the impact that both washing solvent and TCP content have on the biodegradation, in vitro bioactivity and osteoconduction of xerogels were explored. It was found that calcium and phosphate-containing ethanol-washed xerogels presented in vitro release of calcium (2–12 mg/L) and silicon ions (~60–75 mg/L) after one week of soaking in phosphate-buffered saline (PBS), as revealed by inductive coupled plasma (ICP) spectroscopy analysis. However, only the release of silicon was detected for water-washed samples. Besides, all the samples exhibited in vitro bioactivity in simulated body fluid (SBF), as well as enhanced in vitro cell growth and also significant focal adhesion development and maturation.
Highlights
Afterwards, samples were dried at 80 ◦ C in ambient air pressure, and the resulting sample washing series were labelled as:= Ethanol-Washed_1 Day (E1), Ethanol-Washed_7 Days (E7), and washing forto 30 days (W30), respectively
The results presented here implicate that an ethanol-washed scaffold built of mesoporous silica/chitosan/tricalcium phosphate (TCP) has an attractive design for bone tissue engineering, appearing to be responsible for cell changes compatible with osteoblast differentiation and are promising candidates for clinical use, a number of steps are still to be overcome
SiO2 /CS and SiO2 /CS/TCP micro- and mesoporous hybrid xerogels with high surface areas about 800 m2 ·g−1 and interconnected porosity were obtained by the sol-gel synthesis introduced in this work
Summary
Polymer silica hybrid gels featuring both bioactivity and osteoconductive properties have experienced increasing research attention in recent years as biomaterials for bone tissue engineering [1,2,3,4]. In this sense, a broad range of organic polymers and biopolymers has been contemplated for the preparation of new hybrid silica gels, including collagen [5], gelatin [6], poly e-caprolactone [7], and polysaccharides such as alginate [8], cellulose [9], and chitosan [10]. In case of SiO2 /CS hybrids incorporating cross-linking agents, such as 3-Glycidyloxypropyltrimethoxysilane (GPTMS) [18,19] or genipin [20], and carbon nanotubes (CNTs) [21], the biomedical applications are widespread, and various studies to expand cell proliferation [22] or to promote bone regeneration as scaffold [23] have been accomplished
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
