Sol-Gel Materials for Biomedical Applications

R. (1996) Characterization of sol-gel surfaces for biomedical applications. Journal of Materials Science Materials in Medicine, 7, 255-60. 

Sol-gel materials have the potential to succeed in these applications where traditional materials have failed. This chapter will cover the two main broad applications of sol-gel materials in biomedical applications in drug delivery and scaffolds for regenerative medicine. It will begin with bioactive glasses and hybrids before moving to submicron particles and nanoparticles for drug delivery. 

Chiriac, A.P., Neamtu, I., Nita, L.E., and Nistor, M.T. (2011) Sol-gel based materials for biomedical applications, in The Sol-Gel Process Uniformity, Polymers and Applications, Nova Science Publishers, Hauppauge, NY, ISBN 978-1-61761-621-1. 

Titanium is one of the most biocompatible materials and is widely used as dental and orthopaedic implants. An oxide layer is formed at the sruface of the titanium metal onto which cells should be able to grow. Therefore sol-gel derived titania coatings are being developed for biomedical applications. Osteoblast-like and bone marrow stromal cells have been shown to attach well to these sol-gel coating and spread normally at their surface (Haddow, 2000). Such properties could open new opportunities for the encapsulation of living cells within titania gels ... 

Yokogawa Y., Nishizawa K., Nagata F., Kameyama T. Bioactive properties ofchitin/chitosan-calcium phosphate composite materials. J. Sol-Gel Sci. Technol. 2001 21 105-113 Yoshioka T., Tsuru K., Hayakawa S., Osaka A. Preparation of alginic acid layers on stainless-steel substrates for biomedical applications. Biomaterials 2003 24 2889-2894... 

Contrarily, the sol-gel process is a wet chemical approach carried out mostly at ambient temperature for the production of nanopartides. As such, the formed particles contain many silanol groups on their surface, which can be easily functionalized, for example, with various chlorosilanes or alkoxysilanes [9]. In addition, the silica-based sol-gel process often produces stable suspensions that can be stored for a long time [10]. The precursors of the sol-gel materials can be easily prepared and purified therefore, very pure silica particles are produced, which is important for applications in electronics and the biomedical field. Due to its ability to control the particle size, size distribution, and morphology through systematic monitoring of reaction parameters, the sol-gel process is ideally suited for many different applications. 

Chastellain et al. confirmed the sensitivity of the power loss with respect to the size distribution, comparing power losses of silica-iron oxide nanocomposites synthesized by different routes [92]. Although for biomedical applications iron oxides are the main materials being studied because of their low toxicity, several studies have also evaluated the role of other materials for hyperthermia such as manganese perovskite nanoparticles [33]. The heating properties of several ferrites synthesized by sol-gel (Fe, Li, Ni/Zn/Cu, Co, Co/Ni, Ba, and Sr ferrites) have also been characterized [93]. However, in this kind of studies, it is complicated to isolate the effect of the composition on the heating properties of the material from other factors that may influence as well, such as the particle size or size distribution. 

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