Antibacterial Surfaces and Coatings Produced by Plasma Techniques

Bacterial colonisation of synthetic materials surfaces is an important problem in many fields and consequently there have been considerable efforts over many decades to find solutions. This review discusses plasma-based strategies for combating infections at biomedical implants and devices, caused by the attachment of bacteria and their subsequent biofilm formation on device surfaces. Plasma polymerisation and plasma treatment have become attractive modalities for developing antibacterial coatings and various strategies have been reported. Plasma polymers have been used as reservoirs loaded with antibacterial agents that are subsequently released. Plasma polymer layers can also serve as a diffusion barrier to control the release rate. Plasma-modified surfaces are also utilised as functional coatings for attachment of biocidal or bacteriostatic molecules. A popular strategy continues to be the use of silver ions or silver nanoparticles in polymer matrices. Another popular approach comprises the use of quaternary amine compounds on surfaces. In both cases, antibacterial activity is indeed obtained, but damage to human cells and tissue remains a concern. Alternative approaches utilising the covalent immobilisation of antibiotic molecules are discussed. We also assess existing strategies and their potential usefulness. In this work, we review plasma-based strategies for creating antibacterial surfaces or coatings to combat bacterial infections and biofilm formation on surfaces of biomedical implants and devices. Included is the use of covalent grafting of antibiotics onto plasma polymer surfaces. Advantages and disadvantages are discussed with illustrative examples for the various strategies.