Abstract
Controlling bioaerosols has become more important with increasing participation in indoor activities. Treatments using natural-product nanomaterials are a promising technique because of their relatively low toxicity compared to inorganic nanomaterials such as silver nanoparticles or carbon nanotubes. In this study, antimicrobial filters were fabricated from natural Euscaphis japonica nanoparticles, which were produced by nebulizing E. japonica extract. The coated filters were assessed in terms of pressure drop, antimicrobial activity, filtration efficiency, major chemical components, and cytotoxicity. Pressure drop and antimicrobial activity increased as a function of nanoparticle deposition time (590, 855, and 1150 µg/cm2filter at 3-, 6-, and 9-min depositions, respectively). In filter tests, the antimicrobial efficacy was greater against Staphylococcus epidermidis than Micrococcus luteus; ~61, ~73, and ~82% of M. luteus cells were inactivated on filters that had been coated for 3, 6, and 9 min, respectively, while the corresponding values were ~78, ~88, and ~94% with S. epidermidis. Although statistically significant differences in filtration performance were not observed between samples as a function of deposition time, the average filtration efficacy was slightly higher for S. epidermidis aerosols (~97%) than for M. luteus aerosols (~95%). High-performance liquid chromatography (HPLC) and electrospray ionization-tandem mass spectrometry (ESI/MS) analyses confirmed that the major chemical compounds in the E. japonica extract were 1(ß)-O-galloyl pedunculagin, quercetin-3-O-glucuronide, and kaempferol-3-O-glucoside. In vitro cytotoxicity and disk diffusion tests showed that E. japonica nanoparticles were less toxic and exhibited stronger antimicrobial activity toward some bacterial strains than a reference soluble nickel compound, which is classified as a human carcinogen. This study provides valuable information for the development of a bioaerosol control system that is environmental friendly and suitable for use in indoor environments.
Highlights
Bioaerosols, which are aerosols of biological origin, may include intact microorganisms and/or parts or products of organisms [1]
High-performance liquid chromatography (HPLC) and electrospray ionization-tandem mass spectrometry (ESI/MS) analyses showed that the major chemical compounds in the E. japonica extract were 1(ß)-O-galloyl pedunculagin, quercetin-3-O-glucuronide, and kaempferol-3-O-glucoside
In vitro cytotoxicity and disk diffusion tests showed that E. japonica nanoparticles were less toxic and had stronger antimicrobial activity on some bacterial strains than the soluble nickel compound (SNC), which is classified as a human carcinogen
Summary
Bioaerosols, which are aerosols of biological origin, may include intact microorganisms and/or parts or products of organisms [1]. Previous studies have shown that air filtration technologies employing antimicrobial inorganic nanoparticles are effective in controlling bacterial aerosols. Due to the outstanding antimicrobial activity of these materials, they have been extensively studied and applied in a variety of fields including indoor air quality (IAQ) and human health, air filtration, clothing manufacturing, electronics, food processing, cosmetics, and medical devices [20,21]. Carbon nanotubes (CNTs) have been applied to the control of water quality and IAQ. In their aquatic dispersion, CNTs showed strong antimicrobial activities as the reduction in bacterial viability reached a maximum of ~6 log, and in combination with Ag nanoparticles enhanced the antimicrobial activity of air filters. Single-walled CNTs are more toxic to bacteria than multi-walled CNTs [23,24,25]
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