Model Organic Surfaces to Probe Marine Bacterial Adhesion Kinetics by Surface Plasmon Resonance

Abstract

Understanding how bacteria adhere to a surface is a critical step in the development of novel materials and coatings to prevent bacteria forming biofilms. Here, surface plasmon resonance (SPR) spectroscopy, in combination with self‐assembled monolayers (SAMs) that have different backbone structures and/or functional groups, is used for the first time to study the initial stages of bacterial adhesion to surfaces (i.e., initial interaction of cells with a surface, a process governed by van der Waals, electrostatic, and hydrophobic interactions). The work highlights SPR spectroscopy as a powerful and unique approach to probe bacterial adhesion in real time. SPR spectral data reveal different kinetics of adhesion for the interaction of two marine bacterial species (Marinobacter hydrocarbonoclasticus and Cobetia marina) to a range of organosulfur SAMs. Furthermore, the extent of adhesion is dependent on the backbone structures and functional groups of the SAMs. The role of extracellular polymeric substances (EPS) in bacterial adhesion is also investigated. Pre‐conditioning experiments with cell‐free culture supernatants, containing planktonic EPS, allow quantification of the amount adsorbed onto surfaces and directly account for the impact of EPS adsorption on bacterial adhesion in the assay. While the physicochemical characteristics of the surfaces play a significant role in determining bacterial cell adhesion for low levels of conditioning by planktonic EPS, greater levels of conditioning by EPS reduce the difference between surfaces.

Adsorption of Acacia Gum on Self-Assembled Monolayer Surfaces: A Comprehensive Study Using QCM-D and MP-SPR

“…SAM thicknesses were around 1.70 nm at the three studied pHs for all groups except for NH 2 , where the thickness was double. The values are in agreement with previous studies. − ,, The difference in NH 2 SAM thickness is probably due to steric constraints induced by hydrogen atoms overlapping. The SAM thicknesses were also measured by ellipsometry, right after the SAM formation, for comparison, and the present similar results were compared to those obtained using MP-SPR.…”

“…SAM formations were characterized by contact angle measurements, and their thicknesses were measured by MP-SPR and ellipsometry. The obtained contact angles of SAM surfaces (Table ) are consistent with the literature data. ,− Images of contact angle measurements at pH 5 in both methods are available in Table S2. As expected, the SD contact angle measurements suggested the most hydrophobic surface is −CH 3 (104° ± 2°), while the surfaces coated with the other groups are more polar: with −OH: 26° ± 4°; with – NH 2 : 67° ± 4°; and with −COOH: 22° ± 1°.…”

Chemical Functionalization of the Zinc Selenide Surface and Its Impact on Lactobacillus rhamnosus GG Biofilms

“…LGG attaches quicker on positively charged substrates than on hydroxyl and hydrophobic ones. Overall, this result is in accordance with other works demonstrating faster adhesion rates of different bacterial species on SAMs terminated with amine groups. ,, Furthermore, it has been claimed that bacterial cells attach preferentially to hydrophobic materials (materials with low surface energy) due (i) to a mismatch between their surface energy and a typically higher surface energy of liquids in which cells are suspended and (ii) to lack of water at the interface. , In this work, however, it was shown that LGG is able to attach on substrates regardless of their surface energy. This result is in accordance with the recent study, in which it was suggested that the surface energy alone does not allow predicting bacterial attachment, as this process is governed by multiple mechanisms including the surface interaction of extending from cell appendage molecules and gene regulation .…”

Bacterially Antiadhesive, Optically Transparent Surfaces Inspired from Rice Leaves

“…On the other hand, the number of adhering bacteria increased linearly with increasing flow time for pristine and methylated quartz window surfaces (Figure c, d and Table S1). The previous studies reported that the initial stages of bacterial adhesion tend to follow a linear adhesion kinetics with respect to time, − which is consistent with the trends observed in pristine and methylated quartz surfaces. The loss of sensitivity in biosensors due to the accumulation of bacteria on flow chamber windows is a major problem in diagnostic assays .…”