Engineering Graphene Oxide based Nanocomposite Paints against Marine Biofouling

海洋生物污染，即暴露在海水中的各种海洋微生物、植物、藻类和贝类在船体上的积累和定居，给海洋运输带来了重大问题1。例如，基于生物污垢的摩擦效应导致速度下降，燃油消耗增加40%以弥补损失；因此，国际海事组织(2009年)估计，如果不开发新的高效技术，到2020年，温室气体排放(二氧化碳和二氧化硫)预计将增加38%-72%。目前，已经开发了许多防污技术和涂料来解决这个问题；然而，如果对环境无害，例如硅橡胶，它们就不那么有效，不适合静止或缓慢移动的船舶。目前有效的防污剂通过释放重金属(铜、锡或锌)，在某些情况下，如三丁基锡，扰乱非目标生物的内分泌系统，与有害的、往往是非特异性的毒性有关。因此，非常需要开发高效和环境友好的方法来解决海洋生物污损问题。 石墨烯是石墨单原子层，具有超高的电学、热传导性和力学性能。最近，人们发现氧化石墨烯(GO)，即用羰基、环氧基和羟基衍生的石墨烯薄片，具有固有的杀菌性能。在我的团队中，最近我们发现氯化钠的存在可以显著增加少量H_2O_2产生的羟基自由基的数量，即增强GO的杀菌效果。当将纳米复合材料组合在一起时，由于每个组分所具有的独特性能(即GO的高杀菌效果、CuO纳米颗粒的自清洁性能和层状双氢氧化物(LDH)的催化效率)，在海水中存在高浓度氯的情况下，GO作为其他纳米材料(如氧化锌和银纳米颗粒7)的复合材料可以协同增强杀菌效果。因此，我们推测，GO与其他纳米酶组成的复合体，可能是研制海洋船舶防生物污损涂料的有效候选者。由于GO的巨大表面积和微不足道的重量，这种涂料可以有效地用于工业和娱乐航运应用。拟议项目的目标是测试使用这种纳米复合材料防止海洋污染的可行性。

Marine biofouling, the accumulation and colonization of various marine microorganisms, plants, algae, and shellfish on vessels’ hull exposed to seawater, generates significant problems for marine shipping1. For example, biofouling based frictional effects results in decreased speeds and up to 40% increased fuel consumption to compensate; as a result, the International Maritime Organization (2009) estimates that greenhouse emissions (CO2 and SO2) would be expected to increase 38-72% by 2020 if no new efficient technology is developed. Currently, many antifouling technologies and paints have been developed to address the issue; however, if environmentally benign such as silicone elastomers, they are less effective and unsuitable for stationary or slowing moving vessels. Current effective anti-fouling agents are associated with adverse and often non-specific toxicity through their release of heavy metals (copper, tin or zinc) which in some cases such a tributyltin, disrupted endocrine systems of non-target organisms. Consequently, it is highly desirable to develop efficient and environmental friendly approaches to address marine biofouling. Graphene, the single atomic layer of graphite, possesses many extraordinary properties such as super high electrical, thermal conductance and mechanical properties. Recently, it was found that graphene oxide (GO), graphene sheets derivatized with carbonyl, epoxy, and hydroxyl groups, have intrinsic bactericidal properties6. In my group, recently we found the presence of NaCl could significantly increase the amount of hydroxyl radicals generated with a small amount of H2O2, namely, enhancing bactericidal effects of GO. When nanocomposite materials are combined, the unique properties contributed by each constituent (i.e., high bactericidal effect from GO, self-cleaning properties from CuO NPs, and catalytic efficiency properties from layered double hydroxides (LDHs)), the bactericidal effect can be synergistically enhanced when GO is produced as a composite with other nanomaterials, such as ZnO and silver nanoparticles7, in the presence of high concentration of chloride as in sea water. Consequently, we hypothesize that GO, structured as a composite with other nanozymes, may be an effective candidate for formulating anti-biofouling paints for marine vessels. With the huge surface area and negligible weight of GO, the paint could be effective in industrial and recreational shipping applications. The objective of the proposed project is to test the feasibility of using such nanocomposite materials to prevent marine fouling.