Superhydrophobic Hybrid Nanoparticle Coatings Against Biofilm Growth

Device-related infections are a major burden both to the patients and the healthcare system. These infections often occur due to biofilm formation. Biofilms are dense microcolonies of bacteria adherent to a surface that secrete a glue-like matrix of extracellular polymeric substances. Since biofilms are often resistant to conventional antimicrobial interventions, their formation can lead to severe and persistent infections. They often require the removal of the device and can lead to severe complications. These biofilm-based infections urgently call for the development of new therapeutic or preventative strategies.¹<br/>An attractive approach to prevent biofilm formation is the physicochemical modification of the surface. Such a modification can prevent the initial attachment of bacteria and therefore prevents the formation of the microcolonies, which could become a biofilm. Surface charge, surface hydrophobicity, and surface composition significantly impact the bacteria's attachment. This has been successfully applied to design hydrophobic and superhydrophobic surfaces that can reduce the colonization and adhesion of bacteria and prevent biofilm formation. Rare earth oxides have been successfully applied for the development of hydrophobic and superhydrophobic surfaces due to the adsorption of gaseous organic compounds. However, a thorough characterization of the antibiofilm properties and comparison with other metal oxides is lacking.^1,2<br/>Flame spray pyrolysis was used here to produce hydrophobic and hydrophilic nanoparticle coatings of rare earth oxides and other metal oxides to investigate the dependence of biofilm formation on surface hydrophobicity and composition. Nanoparticles were deposited directly on substrates by flame spray pyrolysis in a single step. In this technique, a combustible liquid precursor solution containing the metal of choice is atomized and subsequently ignited.³ The coatings were fabricated by depositing highly porous metal oxide nanoparticle coatings onto a water-cooled substrate.<br/>The initial hydrophilic coating was converted to a hydrophobic coating by the adsorption or infusion of silicone oil. By tuning the metal oxide coating and silicone oil a range of stable hydrophobic and hydrophilic coatings were prepared and their effect on biofilm formation investigated.<br/>The affinity of metal oxide and rare earth oxide nanoparticle coatings to adsorb volatile organic compounds and the subsequent wettability of the coatings was investigated. The coatings were applied and assessed for the inhibition of biofilm formation by clinically relevant pathogens on medical device mimicking surfaces.<br/><br/>This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (ERC Grant agreement n 758705). Funding from the Karolinska Institutet, the Swedish Research Council (2021-05494) and the Swedish Foundation for Strategic Research (SSF) (FFL18-0043) is kindly acknowledged.<br/><br/>1. Chan Y, Wu XH, Chieng BW, Ibrahim NA, Then YY. <i>Nanomaterials</i>. 2021;11(4):1046<br/>2. Oh J, Orejon D, Park W, et al. <i>iScience</i>. 2022;25(1):103691.<br/>3. Meierhofer F, Mädler L, Fritsching U. <i>AIChE Journal</i>. 2020;66(2):e16885.