Electrophoretic Deposition of Calcium Phosphate Coatings

Among the earliest application of EPD in the field of biomaterials the work by Ducheyne etal. (1986,1990) stands out, followed by further input from the studies by Zhitomirsky and Gal-Or (1997), Roether et al. (2002), Boccaccini et al. (2006) and Boccaccini et al. (2009). Comprehensive reviews are available from Besra and Liu (2007), Boccaccini etal. (2010), Dickerson and Boccaccini (2012), Chew, Zein and Ahmad (2012), Dorozhkin (2014) and Kaabi Falahieh Asl, Nemeth and Tan (2014). 

A double layer consisting of a dense inner Ti02 film produced by PEO and a top HAp coating produced by EPD was thought to improve both the corrosion resistance and the osseoconductive properties of Ti6Al4V alloy (Nie, Leyland and 

Matthews, 2000). A phosphate salt solution and an aqueous suspension of HAp powder were used as an electrolyte for PEO and EPD, respectively. The corrosion resistance was assessed by potentiodynamic polarisation tests in a buffered physiological solution (see also Kwok et al., 2009). The results of this study indicated that a hybrid combination of PEO and EPD produces an osseoconductive phase-pure ITAp layer and an anticorrosive titania interlayer that promise to provide good mechanical and biochemical stability in the highly corrosive environment of the human body. Other studies involving titania bond coats include Albayrak and Altintas, 2010 Paluszkiewicz, Dlugon andKwiatek, 2012 Rath etal., 2012 and Jain etal. (2013). 

Significantly improved ALP activity and cytoskeleton organisation of MG63 cell line cultured on EDP hydroxyapatite-coated cp-Ti substrates were observed by Rad etal. (2014). 

Several studies were devoted to EPD of hydroxyapatite coatings reinforced with either CNTs (Kaya, 2008 Lin et al., 2008 Zhang et al., 2011), chitosan (Mah-moodi et al., 2013) or alumina (Wang, Ni and Huang, 2008). Other ceramics of importance for biomedical applications such as alumina (Salman, Jassim and Al-Zubaydi, 2011) and zirconia (Ananth et al., 2013) were deposited by EPD onto Ti alloy surfaces. 

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