Layer-by-layer deposited hybrid polymer coatings based on polysaccharides and zwitterionic silanes with marine antifouling properties Wenfa Yu†, Yongxiang Wang†, Patricia Gnutt†, Robin Wanka†, Lutz M. K. Krause†, John A. Finlay‡, Anthony S. Clare‡, Axel Rosenhahn†* † Analytical Chemistry- Biointerfaces, Ruhr University Bochum, Bochum, Germany ‡ School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom Abstract: Polyelectrolyte multilayer (PEM) assembly is a versatile tool to construct low-fouling coatings. For application in the marine environment, their structure needs to be stabilized by covalent linkage. Here we introduce an approach for spin coating of silane-based sol-gel chemistries using layer-by-layer assembly of polysaccharide- based hybrid polymer coatings (LBLHPs). The silane sol-gel chemistry allows the films to be crosslinked under water-based and mild reaction conditions. Two different silanes were used for this purpose, a conventional triethoxymethyl silane and a de-novo synthesized zwitterionic silane. The polysaccharide-silane hybrid polymer coatings were thoroughly characterized with spectroscopic ellipsometry, water contact angle (WCA) goniometry, attenuated total reflection – Fourier-transform infrared spectroscopy, and atomic force microscopy. The coatings showed good stability in seawater, had smooth surfaces, a high degree of hydration, and WCAs below or close to the Berg limit. LBLHPs showed low-fouling properties in biological assays against nonspecific protein adsorption, attachment of the diatom Navicula perminuta and settlement of zoospores of the macroalga Ulva linza. Keywords: Layer-by-layer, polysaccharides, sol-gel chemistry, hybrid polymers, zwitterionic silanes, marine antifouling 1, Introduction Marine biofouling refers to the accumulation of biological materials on surfaces, that are immersed in the sea. 1,2 The processes include the rapid accumulation of dissolved organic materials and the attachment of biological species such as bacteria, diatoms, micro- and macroalgae, and invertebrates such as barnacles and mussels. 2 Marine biofouling on artificial structures leads to massive ecological and economic costs. For instance, in 2011 it was estimated that for a midsized naval ship the financial loss caused by biofouling is 56 Million US Dollars per year. 3 The drag forces exerted on ships are significantly increased once the hulls are fouled with organisms, resulting in greater fuel consumption and greenhouse gas emissions. As vessels affected by biofouling travel oceans worldwide, they are also a vector for the transfer