Coating of Material with Biosurfactant Compounds

Biosurfactants produced by Pseudomonas aeruginosa SB24 (rhamnolipid congeners), Bacillus amyloliquefaciens ST34 (surfactin and bacillomycin L analogues and homologues) and pigmented (P1) and non-pigmented (NP1) Serratia marcescens strains (serratamolide and glucosamine derivative homologues) were immobilised onto the surface of HDPE, PVC and stainless steel grade 304. To introduce functional groups (hydroxyl groups) to the surface of the materials, the materials were first treated with a Piranha solution and silanized with a 3-triethoxysilylpropan-1-amine (APTES) linker. The lipopeptides and glycolipid compounds were then chemically modified and covalently coupled to the APTES linker on the respective materials. 

Surface immobilisation of the biosurfactants onto the material surfaces was confirmed using attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy coupled to backscattered electron imaging-energy dispersive x-ray spectroscopy and water contact angle measurements. The coating and immobilization methods provide covalent linkages between the antimicrobial biosurfactant compounds and the APTES-functionalised material. The covalent nature of the bonding may be expected to reduce leaching, enhance long-term stability and increase the duration of antimicrobial efficacy. The biosurfactant coated materials have the potential to be exploited as biomaterials to prevent or delay the onset of biofilm formation.