Self-Disinfecting Paints with the Natural Antimicrobial Substances: Colophony and Curcumin.

Micaela Machado Querido,Cristiana Costa Pereira,Ivo Paulo,Nuno Barbosa,Sriram Hariharakrishnan,Rui Galhano Dos Santos,João Paulo Teixeira,João Moura Bordado,Daniel Rocha

doi:10.3390/antibiotics10111351

Abstract

The risk of infection arising from indirect sources—namely, contaminated surfaces—has been proved, particularly in healthcare facilities. In the attempt to minimize this problem, innumerable research projects involving the development of surfaces with self-disinfecting properties are being conducted. In this work, wall-paints with self-disinfecting properties were developed with the scope of being applied in environments prone to contamination, such as those at healthcare settings. Our approach was to develop new paint formulations containing two natural plant-based products with known antimicrobial activity—colophony (CLF) and curcumin (CUR). The natural substances were separately incorporated on a commercial paint and their antibacterial activity was evaluated with several bacterial species following ISO 22196. To assess the paints’ safety, cytotoxicity tests were performed on HaCaT and A549 cell lines, using tests on extracts and direct contact tests, as suggested by the standardized protocol ISO 10993. In general, both paints containing CLF and CUR were able to reduce the bacterial growth after 24 h, compared with the control, the commercial unmodified paint. Colophony was even able to reduce the number of culturable bacteria by over 2 log for Staphylococcus aureus, Escherichia coli, and Bacillus cereus. Regarding the cytotoxicity tests performed (WST-1, NRU, and LDH), both formulations revealed promising results regardless of the methodology used.

Highlights

Contamination of environmental surfaces is a serious public health problem with increasing interest over recent years, and with even more interest since the beginning of the COVID-19 pandemic [1,2]
The paint samples were considered to have antibacterial activity when presenting a value of R equal or superior to 2, according to JIS Z 2801 recommendations [31]
The obtained results show that both developed paints, either containing CUR or CLF, presented antibacterial effects

Summary

Introduction

Contamination of environmental surfaces is a serious public health problem with increasing interest over recent years, and with even more interest since the beginning of the COVID-19 pandemic [1,2]. Surface contamination with pathogens represents considerable risks for people’s health and is one of the major causes of infections spreading among individuals. This issue is even more worrying within healthcare settings, due to the great number of susceptible and frail people present in these spaces [3]. In the attempt to minimize surface contamination in those settings, several studies involving the development of surfaces with self-disinfecting properties have been conducted [4]. Surfaces have been modified to obtain antimicrobial properties in innumerable studies; dangerous chemicals are often applied, representing a potential risk for people contacting the surfaces directly or over longer periods of time. Increasing environmental awareness has led to the demand for less toxic and more ecological materials, including materials developed through science

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