Biomaterials in Clinical Practice by unknow

Author:unknow
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Nanoparticles of these polymers are able to disrupt microbial membranes selectively and efficiently thus inhibiting the growth of Gram-positive bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and fungi, without inducing significant haemolysis over a wide range of concentrations.

2.4 Bioactive Composite Coatings

Although metallic orthopaedic implants are widely used and there is a strong bonding between the bioactive coating (such as HA) and the bone structure, limitations have been identified. For instance, it has been recognized that there could be an issue with the mechanical stability of the interface between the coating and the metallic substrate during surgical operation, after implantation for a prolonged period and/or post-surgery infections, which have caused the failure of the implants. Various strategies have been explored to address such limitations and one of them is to explore the use of bioactive composite coatings.

Bioactive composites have been shown to successfully overcome the brittleness usually attributed to HA and bioglass coatings, while retaining bioactivity, and also to potentially be used to confer additional properties to the coatings (Simchi et al. 2011; Mehdipour and Afshar 2012; Venkateswarlu et al. 2012; Gopi et al. 2013; Pishbin et al. 2013; Cordero-Arias et al. 2015). The combination of bioactive glass/ceramic structure with an appropriate biopolymer to form a biocomposite coating has been shown to be able to transform the brittle HA and bioactive glass coating structure into a compliant and soft composite structure (Chen et al. 2006; Kim et al. 2011), while retaining their bioactivity and enable the incorporation of additional functional properties such as corrosion resistance, antibacterial property and release of biomolecules and drugs (Chen et al. 2006; Rezwan et al. 2006; Simchi et al. 2011; Mehdipour and Afshar 2012; Venkateswarlu et al. 2012; Gopi et al. 2013; Pishbin et al. 2013; Cordero-arias et al. 2015), and removing the need to densify glass ceramics at high temperatures. Various bioactive composite coatings have been investigated and some examples are being highlighted here. These bioactive composite coatings have been deposited onto metallic substrates by various processing techniques. These include sol–gel, thermal spray, laser spinning, plasma spray, electrophoretic and electrochemical deposition (Zheng et al. 2000; Jun et al. 2010a; Boccaccini et al. 2010b; Mehdipour and Afshar 2012; Gopi et al. 2013; Pishbin et al. 2013; Cordero-Arias et al. 2014; Pishbin et al. 2014).

Glasses, 6P57 and 6P68, with thermal expansion coefficients that matched Ti-6Al-4V were prepared and used to coat Ti-6Al-4V. Crack free bioactive composite coatings consisting of 20% of hydroxyapatite (HA) and/or Bioglass (BG) particles (45 µm) in silicate glass coatings were fabricated by enamelling technique on Ti-6Al-4V substrates. HA and/or BG particles were incorporated into these coatings to increase bioactivity of the silicate coatings while maintaining good adhesion to the substrate. There was no apparent reaction at the glass/HA interface at the temperatures 800–840 °C, whereas the BG particles softened and some infiltration of the glass coating occurred during heat treatment. The effectiveness of BG incorporation would depend on the softening temperature of the glass coating, with higher softening temperatures leading to increased degradation of the BG, whereas this was not the case for HA (Gomez-Vega et al.

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