New Insights into Antibacterial and Antifungal Properties, Cytotoxicity and Aquatic Ecotoxicity of Flame Retardant PA6/DOPO-Derivative Nanocomposite Textile Fibers.

Jelena Vasiljević,Danaja Štular,Janja Zajc,Brigita Tomšič,Matic Šobak,Ivan Jerman,Gabriela Kalčíková,Marija Čolović,Andrej Demšar,Vid Simon Šelih,Barbara Simončič

doi:10.3390/polym13060905

Jelena Vasiljević, Danaja Štular + Show 9 more

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https://doi.org/10.3390/polym13060905

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Abstract

The aim of this study was to evaluate the antibacterial and antifungal activity, cytotoxicity, leaching, and ecotoxicity of novel flame retardant polyamide 6 (PA6) textile fibers developed by our research group. The textile fibers were produced by the incorporation of flame-retardant bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (PHED) in the PA6 matrix during the in situ polymerization process at concentrations equal to 10 and 15 wt% (PA6/10PHED and PA6/15PHED, respectively). Whilst the nanodispersed PHED provided highly efficient flame retardancy, its biological activity led to excellent antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as excellent antifungal activity against Aspergillus niger and Candida albicans. The results confirmed leaching of the PHED, but the tested leachates did not cause any measurable toxic effect to the duckweed Lemna minor. The in vitro cytotoxicity of the leached PHED from the PA6/15PHED sample was confirmed for human cells from adipose tissue in direct and prolonged contact. The targeted biological activity of the organophosphinate flame retardant could be beneficial for the development of PA6 textile materials with multifunctional properties and the low ecotoxicity profile, while the PHED’s leaching and cytotoxicity limit their application involving the washing processes and direct contact with the skin.

Highlights

Flame retardants (FRs) represent a class of functional materials with different chemistries tailored for application to specific flammable materials, e.g., polymers or plastics, textiles, and foams
The flame retardant phosphaphenanthrene-10-oxide (DOPO) derivative (PHED) was applied at these two concentrations because we have previously shown that 10 wt % of this flame retardant additive provides the increased thermo-oxidative stability of the polyamide 6 (PA6) textile filament, while 15 wt % of this FR is required to achieve a substantial reduction in the flammability of the melt drops produced in the vertical flammability test of the fiber strand sample [31]
In order to investigate the antibacterial activity of the incorporated PHED compound in the PA6 textile fibers, the pathogenic bacteria E. coli and S. aureus were used as models for Gram-negative and Gram-positive bacteria, respectively [51,52]

Summary

Introduction

Flame retardants (FRs) represent a class of functional materials with different chemistries tailored for application to specific flammable materials, e.g., polymers or plastics, textiles, and foams. Organophosphorus compounds (OP), i.e., organophosphates, organophosphonates, organophosphinates, organoposphine oxide, and organophosphites, are currently being intensively investigated as alternatives to PBT flame retardants due to due the chemical versatility of phosphorus’ different oxidation states and their ability to provide effective flame retardant protection in both the condensed and gas phases [12,13,14,15,16,17,18,19,20]. Organophosphate esters from both flame retardant and pesticide application are ubiquitous in abiotic, including air, water, dust, soil, sediment, and sludge, and biotic matrices, including birds, fish, and human tissue [21,22,23]. Estill et al reported that concentrations of organophosphate FR in air in the manufacturing, construction, and service sectors were higher and more prevalent than those of polybrominated diphenyl ethers [25]

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