A sulfobetaine containing-polymethylmethacrylate surface coating as an excellent antifouling agent against Chlorella sp

Biofouling represents one of the major issues in Photobioreactors (PBRs) for microalgae cultivation. At this aim, a series of zwitterionic-containing polymethylmethacrylate (PMMA) co-ter-polymers, differing in the molar percentage of sulfobetaine (SBMA)- and 2-hydroxyethylmethacrylate (HEMA) components were designed as antifouling (AF) potential coatings for inner PMMA surface of photobioreactors (PBRs). Among these, the sample named PSBM, P(HEMA-co-MMA-co-SBMA), showing the best film capabilities on PMMA slides, was selected, characterized and its AF activity investigated. High transparent and thin PSBM films, as confirmed by AFM and optical transparency investigations, were obtained by a simple drop-casting procedure using a basic isopropylalcohol/water mixture. AFM images of raw PSBM and PSBM films clearly indicate that a conformational change occurred upon treatment with electrolytes. PSBM was further characterized by ATR-FTIR Spectroscopy, Dynamic Light Scattering, X-Ray Photoelectron Spectroscopy, Thermogravimetric analysis, Differential Scanning Calorimetry and Static Water Contact Angle (WCA) investigations. Consistent with hydrophilic behavior, the PSBM surface provided a WCA of 60.9 ± 0.8° which, interestingly, decreased to 27.7 ± 1.2° after immersion in electrolyte culture media. PSBM films displayed a high satisfactory AF behavior in that a rare or no cell adhesion was observed when placed for 7 days in a suspension of the green microalga Chlorella sp. For comparison, the experiments were carried out with untreated and rough PMMA surfaces.