Coatings consisting in gentamicin-containing nanocapsules have been synthetized by means of an aerosol-assisted atmospheric pressure plasma deposition process. The influence of different parameters affecting the process has been extensively investigated by means of a morphological and chemical characterization of the coatings. Scanning electron microscopy highlighted the presence of nanocapsules whose size and abundance depend on power input and deposition time. A detailed analysis carried out with matrix-assisted laser desorption ionization coupled to high-resolution mass spectrometry allowed to detect and identify the presence of gentamicin embedded in the coatings and its rearrangement, as a result of the interaction with the plasma. The release of gentamicin in water has been monitored by means of UV-vis fluorescence spectroscopy, and its biological activity has been evaluated as well by the disk diffusion assay against Staphylococcus aureus and Pseudomonas aeruginosa. It is confirmed that the antibacterial activity of gentamicin is preserved in the plasma-deposited coatings. Preliminary cytocompatibility investigations indicated that eukaryotic cells well tolerate the release of gentamicin from the coatings.

A coating consisting of a copolymer of methacrylic acid and ethylene glycol dimethacrylate was deposited over a gentamicin film by initiated chemical vapor deposition with the aim of controlling the drug release. Gentamicin release in water was monitored by means of conductance measurements and of UV-vis Fluorescence Spectroscopy. The influence of the polymer chemical composition, specifically of its crosslinking density, has been investigated as a tool to control the swelling behavior of the initiated chemical vapor deposition (iCVD) coating in water, and therefore its ability to release the drug. Agar diffusion test and microbroth dilution assays against Staphylococcus aureus and Pseudomonas aeruginosa on cellulose coated substrates confirmed that the antibacterial activity of the drug released by the coating was retained, though the release of gentamicin was not complete.

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In this review an overview is given on bio-composite coatings, on their applications and the plasma-based processes for their deposition. In particular, we describe the innovative possibility to deposit, via aerosol-assisted atmospheric pressure plasma, drug containing nano-capsules in a one-step process. The application of these peculiar bio-composite materials as cyto-compatible bactericidal drug release coatings have been examined, with different molecules embedded in the same polyethylene-like plasma-deposited matrix: vancomycin, gentamicin and lysozyme. In conclusion, a hypothesis on the formation mechanisms of the nano-capsules is proposed, which could be very interesting for numerous potential applications.