Effective disinfection of airborne microbial contamination in hospital wards using a zero‐valent nano‐silver/TiO ₂ ‐chitosan composite

Abstract

A novel antimicrobial composite of zero‐valent silver nanoparticles (AgNPs), titania (TiO2), and chitosan (CS) was prepared via photochemical deposition of AgNPs on a CS‐TiO2 matrix (AgNPs@CS‐TiO2). Electron microscopy showed that the AgNPs were well dispersed on the CS‐TiO2, with diameters of 6.69‐8.84 nm. X‐ray photoelectron spectra indicated that most of the AgNPs were reduced to metallic Ag. Fourier‐transform infrared spectroscopy indicated that some AgNPs formed a chelate with CS through coordination of Ag+ with the CS amide II groups. The zones of inhibition of AgNPs@CS‐TiO2 for bacteria (Escherichia coli and Staphylococcus epidermidis) and fungi (Aspergillus niger and Penicillium spinulosum) were 6.72‐11.08 and 5.45‐5.77 mm, respectively, and the minimum (critical) concentrations of AgNPs required to inhibit the growth of bacteria and fungi were 7.57 and 16.51 µg‐Ag/mm2, respectively. The removal efficiency of a AgNPs@TiO2‐CS bed filter for bioaerosols (η) increased with the packing depth, and the optimal filter quality (qF) occurred for packing depths of 2‐4 cm (qF = 0.0285‐0.103 Pa−1; η = 57.6%‐98.2%). When AgNPs@TiO2‐CS bed filters were installed in the ventilation systems of hospital wards, up to 88% of bacteria and 97% of fungi were removed within 30 minutes. Consequently, AgNPs@TiO2‐CS has promising potentials in bioaerosol purification.

Airborne contamination in the food industry: An update on monitoring and disinfection techniques of air

“…The contribution of airborne microorganisms to food contamination has been addressed (Chang, et al, 2019;Chen et al, 2019;Shale & Lues, 2007). Burfoot and Brown (2004) reported that the ratio of microorganisms to total particles may range up to more than two orders of magnitude.…”

“…-++, frequent use; +, occasional use; -, not used. Sources: Burfoot, Hall, Brown, & Xu, 1999;Marriott & Gravani, 2006;Pascual, Llorca, & Canut, 2007;Stanga, 2010;Krishnan et al, 2012;Cutler & Zimmerman, 2011;O'Donnell, Tiwari, Cullen, & Rice, 2012;Christ, Savi, & Scussel, 2016;Zhou, Yang, Lai, & Huang, 2016;Yang, Zhang, Nunayon, Chan, & Lai, 2018;Chen et al, 2019;Masotti et al, 2019.…”

Effectiveness of the Nanosilver/TiO2-Chitosan Antiviral Filter on the Removal of Viral Aerosols

“…The titania-chitosan (TiO 2 -CS) composite was prepared according to our previously reported method. (19) Briefly, 15 g of chitosan was completely dissolved in acetic acid solution (600 mL, 3% v/v, pH = 2.6). Then, 2.4 g of P25 TiO 2 powder (particle size 25-30 nm; Brunauer-Emmett-Teller [BET] surface area 53.3 m 2 /g; 80% in the anatase phase and 20% in the rutile phase) was added to the viscous chitosan solution, and then the slurry was nonstop stirred for 24 hours to obtain a viscous colloid.…”

“…(18) Our previous study has demonstrated the excellent bactericidal efficacy of zero-valent nanosilver/titania-chitosan (nano-Ag 0 /TiO 2 -CS) composite for purifying the supply air in hospital wards. (19) However, due to the different structures and aerosol particle sizes between viruses and bacteria, (20)(21)(22)(23) the antimicrobial efficacy of nano-Ag 0 /TiO 2 -CS against viruses and bacteria would also be different. Thus, the primary aim of this study is to evaluate the filtration efficiency and antiviral efficacy of nano-Ag 0 /TiO 2 -CS filter for viral aerosols, along with the assessment of the infection risk reduction and longterm antiviral efficacy of nano-Ag 0 /TiO 2 -CS.…”

Evaluation of the Bioaerosol Inactivation Ability of Chitosan-Coated Antimicrobial Filters

“…Ozden and Basal (2017) applied polyamide 6/chitosan nanofiber-coated on HEPA filter for controlling bioaerosols [19]. Chen et al (2019) used zero-valent nano-silver/Ti0 2 -chitosan composite filters to remove hospital indoor bioaerosols [20]. Mishra et al (2021) applied lemongrass essential oil loaded on chitosan nanocellulose for inactivating bioaerosols [21].…”