Biomimetic Calcium Phosphate Coatings Deposited on Various Substrates

3 Biomimetic Calcium Phosphate Coatings Deposited on Various Substrates 

Coated substrates used in implantology can be ceramics such as alumina, zirconia or titania, metals such as magnesium and titanium and their alloys, and austenitic medical stainless steels, as well as several biocompatible polymers. In the following text, some recent research will be reviewed. 

Rambo et al. (2006) produced highly porous biomorphous alumina scaffolds by pyrolysis of natural cellulosic sponges that afterwards were infiltrated by aluminium vapour, and subsequently oxidised and sintered. These alumina scaffolds were immersed in highly supersaturated SBF for 4 days to yield a thin (2 pm) calcium phosphate layer with a Ca/P ratio of 1.62, indicating the formation of a Ca-deficient bone-like hydroxyapatite layer. Kim et al. (2003a) had performed similar work on biomorphous zirconia scaffolds previously. 

A supersaturated bioinspired solution was used to coat alumina and zirconia substrates with a thin, poorly crystalline layer of OCP that after heat treatment at 1050 °C for 1 h was converted to hydroxyapatite with particle size of 300 nm (Pribosic, Beranic-Klopcic and Kosmac, 2010). Stefanic et al. (2012) applied a related method to rapidly deposit an OCP layer by a two-step process onto yttria-stabilised tetragonal zirconia polycrystal (Y-TZP). 80vol% Mg-PSZ/20 vol% alumina substrates were used by Nogiwa and Cortes (2006) to deposit biomimetically by immersion in 1.4 SBF a bone-like apatite coating of 15-30 pm thickness, using a bed of either wollastonite ceramics or bioactive glass as an additional source of Ca2+ ions. 

Biomimetic hydroxyapatite deposition routes were investigated on titanium oxide surfaces (Xia etal., 2011), silicon nitride (Chaves Guedes e Silva etal., 2008), wollastonite (Huang, Jiang and Tan, 2004), canasite (Ca5Na3K3Si12O30(OH,F)4) glass ceramic (Miller etal., 2002) and also pyrolytic carbon and carbon-carbon composite (CCC) ceramics (Hoppe etal., 2013). 

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