Biofouling and its control for in situ lab-on-a-chip marine environmental sensors

Abstract

Biofouling is the process by which biological organisms attach to surfaces in an aqueous environment. This occurs on nearly all surfaces in all natural aquatic environments, and can cause problems with the functioning of scientific equipment exposed to the marine environment for extended periods. At the National Oceanographic Centre in Southampton (NOCS), the Centre for Marine Microsystems (CMM) is developing lab-on-chip micro-sensors to monitor the chemical and biological environment in situ in the oceans. Due to the long periods (up to several months) that these sensors will be deployed, biofouling by microbial biofilms is an important concern for the efficient running of these sensors. The aim of this project was therefore to determine the potential level of fouling within the sensors and to investigate the potential use of low-concentration diffusible molecules (LCDMs) to remediate biofouling.
Many of the sensors in development by CMM are designed to sense specific chemical species and they use various chemical reagents to achieve this. The effects of some of these reagents on the formation of biofilms by mixed marine communities were investigated. It was shown that Griess reagent and ortho-phthadialdehyde (OPA), used to sense nitrites and ammonium respectively, effectively stop biofilm formation by killing microorganisms before they can attach to surfaces.
Biofouling on two different polymers, cyclic olefin copolymer (COC) and poly (methyl methacrylate) (PMMA), used in the construction of micro-sensors, was compared with biofouling on glass. No differences were observed between COC and PMMA, however a small but significant difference in surface coverage was observed between glass and COC at the early stages of exposure to the marine environment. The lack of differences between the two polymers suggests that biofouling is not an important consideration when deciding whether to construct sensors from COC or PMMA. However, the larger degree of fouling on hydrophobic COC compared with hydrophilic glass indicates a potential use of surface modifications as an antifouling strategy.
The effects on biofouling of the LCDMs nitric oxide (NO), cis-2-decenoic acid (CDA) and patulin, were investigated to evaluate their potential for anti-fouling in marine micro sensors. All three molecules were shown to reduce the formation of biofilms by mixed marine communities, but colony counts suggested that the effect of patulin was due to toxicity as opposed to a physiological effect. Investigation of biofilm growth in the light and the dark revealed that there was less biofilm formation in the light that the dark and this effect was determined to be due to an interaction with the polystyrene growth substratum.
Analysis of the biofilm communities grown in the presence of LCDMs by denaturing gradient gel electrophoresis (DGGE), showed no clear differences in community profiles depending on the LCDMs. However those biofilms grown in the light appeared to have a greater proportion of Alphaproteobacteria than those grown in the dark.
Further study is needed to determine the level of fouling and the applicability of LCDMs in real micro-sensor systems. However, this study has shown that LCDMs have the potential to remediate, at least in part, the biofouling of marine micro-sensors.

More information

Identifiers

ORCID for Charles W. Keevil: orcid.org/0000-0003-1917-7706

ORCID for Jeremy S. Webb: orcid.org/0000-0003-2068-8589

Catalogue record

Export record