Optimization and Antibacterial Response of N-Halamine Coatings Based on Polydopamine

Nadia Nazi,Catherine Debiemme-Chouvy,Vincent Humblot,Adeline Marguier

doi:10.3390/colloids6010009

Abstract

Due to the ability of microorganisms to first adhere to a material surface and then to lead to the formation of a biofilm, it is essential to develop surfaces that have antimicrobial properties. It is well known that N-halamine coatings allow us to prevent or minimize such phenomena. In the present work, various polydopamine (PDA) coatings containing chloramine functions were studied. In fact, three PDA-based films were formed by the simple immersion of a gold substrate in a dopamine solution, either at pH 8 in the presence or not of polyethyleneimine (PEI), or at pH 5 in the presence of periodate as an oxidant. These films were characterized by polarization modulation reflection absorption infrared spectroscopy and X-ray photoelectron spectroscopy analyses, and by scanning electron microscopy observations. The chlorination of these PDA films was performed by their immersion in a sodium hypochlorite aqueous solution, in order to immobilize Cl(+I) into the (co)polymers (PDA or PDA–PEI). Finally, antibacterial assays towards the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus epidermidis (S. epidermidis) were conducted to compare the bactericidal properties of these three N-halamine coatings. Regardless of the bacteria tested, the PDA coating with the best antibacterial properties is the coating obtained using periodate.

Highlights

The fight against the adhesion and proliferation of bacteria on surfaces is a constant concern and a major medical and socioeconomic issue for our society
Microbiological tests towards Escherichia coli (E. coli) bacteria showed that chlorinated PDA coatings reduced E. coli adhesion by up to 45% compared to uncoated surfaces, while, at the same time, bacterial viability was reduced by 34% with a chlorinated PDA coating compared to initial PDA films
Dopamine monomers are known to self-polymerize upon oxidation within the right concentration and pH conditions

Summary

Introduction

The fight against the adhesion and proliferation of bacteria on surfaces is a constant concern and a major medical and socioeconomic issue for our society. Three main classes of antibacterial coatings can be designed in such a way, either to limit bacterial adhesion, which is called an antiadhesive coating and/or to inhibit the development of bacteria, which are said to be bacteriostatic films, or even to kill bacteria, known as biocidal coatings [13]. These can act by the contact and/or release of antibacterial substances. Bio-based compounds, such as enzymes or antimicrobial peptides, have been considered as alternative routes, but their high cost of production and purification, as well as their relative instability in the face of variations in pH or temperature, restrict their use [19,20,21,22,23]

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Conclusion