Durable antibacterial and UV-protective Ag/TiO2@ fabrics for sustainable biomedical application

Abstract

A facile method was developed to endow cotton fabric with remarkable antibacterial and ultraviolet (UV)-protective properties. The flower-like TiO₂ micro-nanoparticles were first deposited onto cotton fabric surface via hydrothermal deposition method. Then, the Ag NPs with a high deposition density were evenly formed onto TiO₂@cotton surface by sodium hydroxide solution pretreatment and followed by in situ reduction of ANO₃. This work focused on the influence of different hydrothermal reaction durations and the concentration of AgNO₃ on antibacterial activity against relevant microorganisms in medicine as well as on the UV-blocking property. Ag NPs-loaded TiO₂@cotton exhibited high antibacterial activity with an inhibition rate higher than 99% against Staphylococcus aureus and Escherichia coli bacteria. Moreover, the as-prepared cotton fabric coated with Ag NPs and TiO₂ NPs demonstrated outstanding UV protective ability with a high ultraviolet protection factor value of 56.39. Morphological image of the cells revealed a likely loss of viability as a result of the synergistically biocidal effects of TiO₂ and Ag on attached bacteria. These results demonstrate a facile and robust synthesis technology for fabricating multifunctional textiles with a promising biocidal activity against common Gram-negative and Gram-positive bacteria.

Keywords: Ag nanoparticles; TiO2 nanoparticles; UV-shielding; antibacterial; biomedical; fabric.

Figure 1

SEM images of various cotton fabrics. Notes: (A) Pristine cotton, (B) TiC(5), (C) AgC-100, (D) AgTiC(5)-100. Abbreviation: SEM, scanning electron microscopy.

Figure 2

Elements mapping (A–F) and the energy spectrum and elements proportion (G) of AgTiC(5)-100 sample surface.

Figure 3

(A) FTIR spectra and (B) XPS spectra of cotton fabric before and after hydrothermal treatment and in situ deposition of Ag NPs. Corresponding high-resolution XPS spectra of Ti 2p (C) and Ag 3d (D). Abbreviations: au, absorbance unit; BE, binding energy; FTIR, Fourier transform infrared; NPs, nanoparticles; XPS, X-ray photoelectron spectroscopy.

Figure 4

The inhibition zone and inhibition rate of various samples: the numbers 1–7 represent TiO₂@cotton depositing for 5 h (A) and 10 h (B), in situ growth of Ag NPs on TiO₂@cotton with various AgNO₃ concentrations including 6.25 mM, 12.5 mM, 25 mM, 50 mM, 100 mM, and pristine cotton, respectively. Corresponding inhibition rates against E. coli and S. aureus on various samples (C, D). Abbreviations: E. coli, Escherichia coli; NP, nanoparticle; S. aureus, Staphylococcus aureus.

Figure 5

The UV transmittance property test of the pristine cotton and treated cotton with TiO₂ NPs and Ag NPs; inset is the UV transmittance curve of Ag NPs-coated TiO₂@cotton samples. Abbreviations: NP, nanoparticle; UV, ultraviolet.

Figure 6

The stability of the TiC fabric, AgC fabric, and AgTiC fabric for UV-protection property before and after laundering numerous times according to AATCC 61-2006 standard under 2A condition. Abbreviations: AATCC, American Association of Textile Chemists and Colourists; UPF, ultraviolet protection factor; UV, ultraviolet.

Figure 7

The inhibition rates (A) and number of survived bacterial colonies (B) of E. coli on various prepared cotton fabrics after 50 cycles of domestic laundering. Abbreviation: E. coli, Escherichia coli.

Figure 8

SEM morphology of E. coli bacteria adhered on various cotton fabric surfaces after incubating for 4 h (both low resolution and high resolution). Notes: (A, E) Pristine cotton, (B, F) TiO₂@cotton, (C, G) Ag/cotton, (D, H) Ag/TiO₂@cotton. Abbreviations: E. coli, Escherichia coli; SEM, scanning electron microscopy.

Scheme 1

The synthesis of TiO₂ flower-like micro-NPs and Ag NPs coated onto cotton fabric. Abbreviations: NP, nanoparticle; PTO, potassium titanium oxalate.

Scheme 2

The proposed mechanism of antibacterial activity on cotton surface coated with TiO₂ and Ag NPs. Abbreviations: E. coli, Escherichia coli; NP, nanoparticle; CB, conduction band; VB, valence band.