Combining Microscopy Assays of Bacteria-Surface Interactions To Better Evaluate Antimicrobial Polymer Coatings

Abstract

We present and evaluate a combination of methods for validating the efficacy of antimicrobial surfaces. Antimicrobial surfaces/coatings based on contact-killing components can be instrumental to functionalize a wide range of products.

Functionalized Self-Assembled Monolayers: Versatile Strategies to Combat Bacterial Biofilm Formation

“…As we have reviewed the literature that were referenced herein, one challenge in this field that has stood out is the lack of standardization for quantifying biofilm growth. This is a problem in the field of antimicrobial materials in general, and there have been recent reviews calling for more standardization [191], as well as government-issued standard operating procedures [192] and academic research articles [193][194][195] attempting to address this issue. However, many of these tests are for biocides and biofilm inhibitors that operate in vitro rather than specifically at a surface.…”

Preventing E. coli Biofilm Formation with Antimicrobial Peptide-Functionalized Surface Coatings: Recognizing the Dependence on the Bacterial Binding Mode Using Live-Cell Microscopy

“…It should indeed be recognized that in any clinical application, the antibacterial efficacy of a coating relates to a combination of its ability to reduce surface growth, to prevent binding, and to inhibit development of biofilm-specific phenotypes, among which the last are often heterogeneously distributed among bacteria in a population. , Specialized methods to analyze the antibacterial efficacy of coatings, like the CERTIKA test, which aim to measure the release of bacterial cells from a biofilm established on the test surface, and the popular live/dead staining procedure are usually implemented as artificial end-point measurements that do not monitor the biofilm formation dynamically with single-cell resolution. It is therefore difficult to gain mechanistic insights from these tests, and since the procedures require manual intervention, the results are also sensitive to the handling of washing and staining. − In contrast, mechanistic understanding of the bacteria’s response to AMP has been made available from time-resolved live microscopy of single cells featuring fluorescent probes that continuously indicate membrane permeability, oxidative status, etc. ,− The corresponding procedures and analysis are, however, more complex, limiting the settings under which such tests can be done. Thus, there is an imminent need for medium-throughput methods that can monitor dynamically the early events of biofilm formation on antibacterial coatings under conditions that closely resemble the end-usage, therethrough delivering quantitative information about all their different modes of actions.…”

“… 42 − 44 In contrast, mechanistic understanding of the bacteria’s response to AMP has been made available from time-resolved live microscopy of single cells featuring fluorescent probes that continuously indicate membrane permeability, oxidative status, etc. 21 , 45 − 47 The corresponding procedures and analysis are, however, more complex, limiting the settings under which such tests can be done. Thus, there is an imminent need for medium-throughput methods that can monitor dynamically the early events of biofilm formation on antibacterial coatings under conditions that closely resemble the end-usage, therethrough delivering quantitative information about all their different modes of actions.…”

Visualizing Penetration of Fluorescent Dye through Polymer Coatings

“…Polymer coatings are found in a variety of application areas, from food packaging [1][2][3] and automotive paints [4][5][6][7][8] to corrosion prevention [9][10][11][12][13][14] and material decontamination. [15][16][17][18][19][20][21] One of the DOI: 10.1002/marc.202300304 primary functions of coatings is to protect the underlying substrate against external agents, such as solvents, [22][23][24] toxins, [25,26] bacteria, [27][28][29][30][31][32] or corrosive ions, [33][34][35][36][37][38][39] that are harmful to the underlying surface. Since these external agents vary, protective coatings need to be designed for the specific application in question.…”