The rising threats to the worldwide security (military and civilian) attest the need to develop efficient and versatile technological solutions to protect the human being. Specifically, those who put themselves in situations of most exposure—those protecting and caring for the safety of others—should be adequately protected, so that infectious diseases cannot be spread or misused so easily. Current technology in biological protective garments is traditionally based on a multilayered fabric integrating activated carbon as the sorptive agent, and a separate filtrating layer for passive protection. However, the adsorbed contaminants accumulate within the carbon filler over time, turning into secondary contaminants. The clothing becomes too heavy and warm to wear, not breathable, hindering them from performing active work for extended hours. Hence, there is a strong need to select and create innovative materials, fibrous structures with incorporated active agents, offering efficient filtering capability and bioactive protective skills. A rational design of layered compositions is key to ensure lightweight, comfortable, breathable and multifunctional fabrics [
1,
2].
Our proposal relies on the use of textile-based macro-to-nanoscale structures, acting in consonance to reach the intended biocidal effects. A twill fabric composed of cotton and polyamide fibers, hydrophobic but breathable, constitutes the first passive protective barrier. Internally, by resorting to zinc oxide nanoparticles (ZnO NPs) [
3] and a polyurethane-based paste, an active protective barrier was spread by knife coating, using 0.5–2%
w/
v ZnO NPs and 0.25–0.5 mm of thickness. A coating thickness of ≈13 nm was obtained, and parameters such as fabric wettability (water contact angle of ≈130°) and breathability (air permeability of ≈30 L/m
2/s) remained unaffected. Qualitative and quantitatively tests (JIS L 1902 standard) using two representative bacteria species, the gram-positive
Staphylococcus aureus and the gram-negative
Escherichia coli evaluated the front and back sides of the coated textiles following 24 h of incubation, as typically done to screen technical textiles’ action against biological threats [
4]. Those with ZnO NPs successfully eradicated all
S. aureus and
E. coli colonies. Collectively, the strategy here presented is intended to enhance current textile-based options under the scope of bioterrorism, opening new perspectives for the safety of those potentially exposed to biological warfare agents.
Author Contributions
Conceptualization, J.C.A., I.P.M., M.H. and R.F.; methodology, J.C.A., L.M.A., M.S.-S., F.G. and I.P.M.; validation, M.H. and R.F.; formal analysis, J.C.A.; investigation, J.C.A.; data curation, J.C.A., T.F. and M.S.-S.; writing—original draft preparation, J.C.A., M.S.-S., F.G. and I.P.M.; writing—review and editing, J.C.A. and I.P.M.; supervision, M.H. and R.F.; project administration, R.F.; funding acquisition, M.H., F.C. and R.F. All authors have read and agreed to the published version of the manuscript.
Funding
The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), the FEDER funds by means of the Portugal 2020 Competitive Factors Operational Program (POCI), and the Portuguese Government (OE) for funding the project PluriProtech—“Desenvolvimentos de soluções multicamada para proteção ativa contra ameaças NBQR”, ref. POCI-01-0247-FEDER-047012. The authors also acknowledge the strategic funding of UID/CTM/00264/2020 of 2C2T and UIDB/04469/2020 of CEB, given by FCT.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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