Chem. Mater. 2016, 28, 6791−6796.
Recently, the bioadhesive properity of marine mussels have been extensively studied, and the mechanism has been found that all the adhesion proteins contain a kind of rare amino acid 3,4-dihydroxyphenylalanine (DOPA). This component can be oxidized by one electron to a semiquin one or two electrons to a quinone. Subsequent reactivity generates the final cross-links with the surface of materials. With this properity, DOPA and its derivative structure have been utilized to modify the surface properities of materials. For example, after DOPA pre-treatment, the growth factors and other bioactive substance could effectively attach to the surface of biomaterials. However, with the ability to attach onto nearly any surfaces, how to avoid the unnecessary attachment of DOPA is a arduous task. Besides, for marine organisms, such as barnacles, oysters, mussels, etc., they often attach themselves to underwater structures. This adhesion presents a major problem for transoceanic shipping. Because of the resistance that caused by the attachment of marine organisms, fuel burn can increase up compare to a clean hull. Traditionally, coatings releasing biocidal copper（Cu2+）into the surrounding waters could stop attachment by essentially killing everything in the waters around a ship, which severely caused the pollution of the ocean and the destruction of the marine ecological environment. Therefore, it is of great significance to develop a new type of environmentally friendly anti-bioadhesion coating material.
DOPA can be oxidized to a semiquinone or a quinone which subsequently generates the chemical bonding with the surface of materials to form a strong connection. Such insights now allow us to take a mechanism-based approach to minimizing or stopping oxidation reactions of DOPA necessary to form glues and thus the bioadhesion could be weaken. Del Grosso et al., from Purdue University, United States, designed a protocol that 4 kinds of antioxidants and a control compound were each dissolved into a host coating proportionally and painted onto aluminum panels. Mussels were each banded to panels containing different antioxidants as well as bare, uncoated aluminum for comparison. After 3 days culture underwater, adhesion strengths were quantified after animals were removed from the plates, leaving behind attached plaques and threads on the coatings, also did the mussel health. The effect of antioxidant materials on adhesion was studied throughy this experiment. Results showed that average adhesion strength values for mussels attached to each coating containing an antioxidant (or DBT control) displayed less adhesion than the bare, uncoated aluminum control. At 2.5% loadings of antioxidants in the host matrix, animals stuck equally well to all surfaces. With more antioxidants present at 25%, significant decreases in adhesion were found, relative to the DBT control. These tests also revealed that the candidate coatings did not diminish mussels’ health. These kinds of antioxidant substances have a significant effect on reducing the attachment ability, and have no obvious influences on the surrounding ecological environment.