Antibiofouling coatings for PMMA Photobioreactors (PBRS) and Stone-built Cultural Heritage.

The present study was to develop a novel zwitterionic antifouling (AF) coating as an inner wall modifier for the development of a lab-scale planar polymethylmethacrylate (PMMA) PBR prototype for microalgae cultivations (Chapter I). The AF properties of this new coating were tested vs. the microalgae Chlorella sp., Nannochloropsis sp., and Arthrospira (old genus name, Spirulina) maxima,. For comparison, the AF tests were also performed on untreated PMMA and mechanically aged or rough PMMA slides for conventional times of 7 days (CHAPTER II). A tribological approach was utilized to test the performance and sustainability of the new coating over long-term cycles (CHAPTER III). The incorporation of surfactants in the culture media may also represent a promising strategy for counteracting biofouling on the PBR wall surface. These must be used at a controlled concentration to interfere with cell surface interactions without affecting the growth of biomass and cell vitality. In the present study, Polysorbate 80, better known as Tween 80, was tested as a synthetic non-ionic surfactant to prevent cell attachment on PMMA surfaces. At this aim, the growth and the biomass composition profile of the microalgae Chlorella sp. and Nannochloropsis sp. in BG 11 medium at different concentrations of Tween 80 were tested. A medium-term (4 cycles) tribological approach was also applied even in this case (CHAPTER IV). To the above main research activity, the issues related to the conservation of stone cultural heritage were also addressed via the long-term evaluation (5 years) of an AF Ionic Liquid/nanosilica bilayer-based coating designed specifically for lithic materials (CHAPTER V).