RIASSUNTO
ABSTRACT
Antifouling and drag reduction is an important part of ship tribology. During the process of fouling, bacterial biofilms formation is the first step. Algae, barnacles and shells and other large bio fouling organisms attach on the hull because of biofilms. Attachment will be difficult to achieve if the biofilms were destroyed. The study was designed to regulate surface properties of the material by biological surface modification, providing material surface antibacterial properties to destroy biofilm formation. Reaction conditions were optimized and antibacterial surface with preliminary antifouling properties were also prepared. Its antibacterial ability was analyzed in order to provide a theoretical basis for further improving the antibacterial and antifouling property of hull's surface.
INTRODUCTION
Bacterial biofilms form rapidly on almost every surface exposed to a non-aseptic area. The biofilms are difficult to remove or control according to previous research results. Many studies have revealed that biofilm formation rely on the conditioning layer which developed from bacterial and other microorganism. The biofilms will attract a large number of fouling organisms, resulting in adhered fouling on the surface of the metal [Huang, 1984].
Many studies have been utilized for reducing bio fouling of ships. Some coatings with heavy metal ions were used to reduce the adhesion of bio fouling organism, however, those ions would spread into the sea water which caused marine environment pollution. Green techniques should be applied into the drag reduction of ship transportation. Previous experiment showed that the alteration of surface energy of the material surface is related to antifouling of metal surfaces. Fouling will become difficult or defaced desorption becomes very easy when the surface energy of the material is low or ultra-low, which will make it possible to achieve antifouling [Yebra, 2004].
A new concept of bioorganic stainless steel with lower surface energy which yielded by the reaction of peptides and metals has been reported [Ma, 2014]. Pseudomonas aeruginosa can directly bind to stainless steel surfaces through molecular interactions of the type IV pilus through the pilin or PilA protein receptor binding domain (RBD), and some bioorganic metallic material were obtained by the reaction between the pili of microorganisms and steel. Davis et al. proved that electron sharing results in the formation of a novel organic-metallic state of matter and creates new bioorganic metals that have altered surface properties compared to the original metal [Davis, 2011]. Another scholar also proved that indole group of L-tryptophan with a cyclic chain structure can also share electrons with metal to generate a new material. Many experiments indicated that peptides with disulfide bond could easily react with stainless steel. Ren et al designed and produced a peptide from Pseudomonas aeruginosa which can develop a new material via reaction with stainless steel, and the material has a good hydrophobicity [Ren, 2015]. Some short-chain peptides obtained by biological chemical synthesis were applied to the synthesis of new materials [Cao, 2015].