Novos revestimentos poliméricos produzidos via layer-by-layer inibem a formação de biofilmes microbianos

Abstract

Bacterial adhesion and biofilm formation are significant issues associated with microbial infections. Materials with anti-adhesive and antimicrobial properties are required in technological applications, such as in disinfection of drinking water, food packaging and biomedical devices. However, it has been a challenge to prepare durable coatings capable of preventing the development of microbial biofilms. In this sense, this study shows for the first time the production of new polymeric coatings with anti-adhesive and antimicrobial potential. For this, a condensed tannin derivative (cationic amino-functionalized material) was associated with anionic polysaccharides (pectin and iota-carrageenan) to create multilayered polyelectrolytes (PEMs) via layer-by-layer technique. PEMs were prepared from the deposition of polymeric layers on an oxidized glass substrate. The deposition of the polycation (modified tannin), followed by the deposition of the polyanion (pectin or iota-carrageenan), followed until reaching 5 or 15 deposition layers. PEMs were characterized by X-ray photoelectron spectroscopy (XPS), in-situ Fourier transform surface plasmon resonance (FT-SPR), atomic force microscopy and contact angle measurements. Compared to the native glass substrate (non-oxidized material), all PEMs showed roughness and hydrophilic surface. A stability test carried out in phosphate buffer (PBS, pH 7.4) confirmed that PEMs manufactured with 15 layers were durable for up to 7 days of contact with the aqueous medium. Adhesion and proliferation tests against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) showed that PEMs with 15 layers exhibit anti-adhesive and bactericidal activity after 6 and 24 hours of testing. The in vitro antimicrobial test indicated that PEMs can significantly kill and prevent the binding and proliferation of bacteria, especially during initial exposure within the first 6 hours of contact. When compared to control samples (polystyrene films), the results indicate that the polymeric coatings significantly inhibit the formation of microbial biofilm. Therefore, it is suggested that PEMs can be applied as filter coatings avoiding bio-encrustation in drinking water, packaging and coatings in hospitals to prevent microbial contamination.