Poly(VP-co-V3D3), an Insoluble Hydrophilic Copolymer Coating Deposited via Initiated Chemical Vapor Deposition to Prevent Bacterial Adhesion and Biofilm Formation

While bacterial biofilm remains one of the world's major health issues, many traditional strategies for combatting it are being questioned. Indeed, as antibioresistance is rising and other biocides are raising concerns due to their potential toxicity, these curative methods no longer seem to be the solution. Therefore, biomimetic preventive methods, based on impeding bacterial adhesion, are being developed. One strategy is creating superhydrophilic surfaces to which bacteria cannot adhere as a water barrier forms at the interface. Polymer thin films are an efficient way for crafting such surfaces, and more precisely, the vacuum-based method initiated chemical vapor deposition (iCVD) allows the formation of polymers through radical polymerization mechanisms, therefore giving good control over the chemical composition of the resulting coatings. Polyvinylpyrrolidone (poly(VP)) has previously been used for its antibiofouling properties due to its high wettability and can be easily deposited into thin films by iCVD. However, its strong affinity with water makes it soluble, and thus, it cannot be used in bacterial suspensions. By coinjecting the VP precursor with a cross-linker, in this case organosilicate 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3D3), the iCVD technique allows the formation of cross-linked copolymer thin films. The conservation of the functional groups of both monomers, whose proportion can be finely tuned by adjusting the injected fractions of each precursor, was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The Fineman–Ross equation was used to evaluate the reactivity of both monomers, allowing us to describe the copolymer structure. Water contact angle (WCA) and atomic force microscopy (AFM) measurements were carried out to characterize the surface state of the coatings and correlate it with the copolymer composition. Finally, solubility tests were carried out in phosphate buffer saline (PBS), and microbiological adhesion assays were carried out with the model species Escherichia coli to highlight the potential of these copolymers for antifouling applications.