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A series of doped apatites have been deposited onto titanium (V) substrates using a novel ambient temperature blasting process. The potential of these deposited doped apatites as non-colonizing osteoconductive coatings has been evaluated in vitro. XPS, EDX, and gravimetric analysis demonstrated that a high degree of coating incorporation was observed for each material. The modified surfaces were found to produce osteoblast proliferation comparable to, or better than, a hydroxyapatite finish. Promising levels of initial microbial inhibition were observed from the Sr- and Ag-doped surfaces, with the strontium showing prolonged ability to reduce bacteria numbers over a 30-day period. Ion elution profiles have been characterized and linked to the microbial response and based on the results obtained, mechanisms of kill have been suggested. In this study, the direct contact of coated substrate surfaces with microbes was observed to be a significant contributing factor to the antimicrobial performance and the anticolonizing activity. The silver substituted apatite was observed to out-perform both the SrA and ZnA in terms of biofilm inhibition.

This study reports on the effect on the morphology and chemistry of atmospheric pressure plasma deposited nm‐thick coatings (21 ± 3 nm) as the level of exposure to the plasma is systematically altered. Coatings were deposited by directly injecting hexamethyldisiloxane, polydimethylsiloxane or tetramethyldisiloxane liquid precursors through a nebulizer into a helium/oxygen atmospheric pressure plasma. An increase in the level of the precursor was found to be associated with a decrease in the concentration of methyl functional groups in the coating and to an increase of the SiO crosslinking, as demonstrated using surface energy and XPS analysis. This resulted in an increase in the coating refractive index, and in a reduction of the number of surface particulates, as well as of surface roughness.magnified image

By injecting a liquid aerosol precursor directly into a non-equilibrium atmospheric pressure plasma (APP), a controlled, free-radical-induced polymerisation reaction can be initiated with minimal fragmentation of the precursor molecules. This can be used to chemically graft highly complex chemical functionalities directly onto a variety of substrates. This process normally proceeds through polymerisation of unsaturated functional groups on the precursor molecules. In this work, it has been found that compounds that lack such polymerisable groups can be physically dissolved in the liquid precursor and that these chemicals are not directly involved in the plasma reaction. Instead, these chemicals become physically entrapped within the resultant plasma polymer and retain much of their biological and chemical properties. As a preliminary example of such a reaction, the entrapment of various anti-microbial species (quaternary ammonium salts) within glycol and acrylic acid plasma polymers is described. The biological and chemical reactivity of these chemicals is examined using a combination of anti-microbial and XPS investigations.