Sharply Reduced Biofilm Formation from Cobetia marina and in Black Sea Water on Modified Siloxane Coatings

Danail Akuzov,Todorka Vladkova,Lia Franca,Ingo Grunwald

doi:10.3390/coatings8040136

Abstract

Siloxane fouling release coatings are currently the only viable non-toxic commercial alternative to toxic biocide antifouling paints. However, they only partially inhibit biofouling since biofilms remain a major issue. With the aim to improve the bacterial resistance of siloxane coatings modified with non-ionic surfactant (NIS), antioxidant (AO) or both NIS/AO, the ability of PEG-silane co-cross-linker was investigated to reduce Cobetia marina adhesion and multispecies biofilm formation from natural seawater. Surface physical-chemical and physical-mechanical parameters relevant to bio-adhesion were estimated before the testing of the biofilm formation. Slightly reduced biofilm from C. marina and sharply reduced multispecies biofilm, formed in natural sea water, were found on the PEG-silane co-cross-linked coatings without modifying additives. However, both C. marina growth and biofilm formation from natural sea water were sharply reduced on the PEG-silane co-cross-linked coatings containing NIS or AO, even more, no C. marina adhesion was seen on the coating containing NIS and AO simultaneously. Possible explanations of the observed effects are presented in this article. It was concluded that the PEG-silane co-cross-linker, toghether with NIS and AO, can be used as an efficient tool to additionally reduce the bioadhesion of Gram-negative marine bacteria and multispecies biofilm formation on siloxane antifouling coatings.

Highlights

Surface modification by deposition of relevant coatings is one the most often studied approaches in the creation of materials that reduce biofilm formation
Expecting that they can be influenced by the used modifying agents (PEG-silane, non-ionic surfactant (NIS) and AO) and surface characterization of each test surface was carried out before testing the bacterial adhesion and biofilm formation
The mono-species biofilms formed from bacteria C. marina were insignificantly reduced whereas (Figure 4) the multi-species biofilms formed from natural Black sea water (Figure 6) were significantly reduced on the PEG-silane co-cross-linked coatings in the absence of modifying agents

Summary

Introduction

Surface modification by deposition of relevant coatings is one the most often studied approaches in the creation of materials that reduce biofilm formation. Milne [1] was among the first researchers who pointed out the antifouling properties of siloxane (silicone) polymers and observed that the low molecular silicone oils greatly enhance their fouling release properties [2]. These early observations constitute the bases of most siloxane fouling release coatings that facilitate only weak adhesion of macro-fouling organisms and ensure the self-cleaning of high speed moving (about 15 knot and higher) ships by easy detachment (release). The current siloxane fouling release coatings only partially inhibit biofouling since biofilms with their own negative impact remain a major issue

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