Recently, bioaerosols, including the 2019 novel coronavirus, pose a serious threat to global public health. Herein, we introduce a visible-light-activated (VLA) antimicrobial air filter functionalized with titanium dioxide (TiO2)-crystal violet (CV) nanocomposites facilitating abandoned visible light from sunlight or indoor lights. The TiO2-CV based VLA antimicrobial air filters exhibit a potent inactivation rate of ~99.98% and filtration efficiency of ~99.9% against various bioaerosols. Under visible-light, the CV is involved in overall inactivation by inducing reactive oxygen species production both directly (CV itself) and indirectly (in combination with TiO2). Moreover, the susceptibility of the CV to humidity was significantly improved by forming a hydrophobic molecular layer on the TiO2 surface, highlighting its potential applicability in real environments such as exhaled or humid air. We believe this work can open a new avenue for designing and realizing practical antimicrobial technology using ubiquitous visible-light energy against the threat of infectious bioaerosols.

No abstract

No abstract

Real-time on-site monitoring of bioaerosols in an air environment is important for preventing various adverse health effects including respiratory diseases and allergies caused by bioaerosols. Here, we report the development of an on-site automated bioaerosol-monitoring system (ABMS) using integrated units including a wet-cyclone bioaerosol sampler, a thermal-lysis unit for extracting adenosine triphosphate (ATP), an ATPdetection unit based on the immobilization of luciferase/luciferin for bioluminescence reactions, and a photomultiplier tube-based detector. The performance of the bioaerosol detection system was verified using Escherichia coli (E. coli) as a model source. Each unit was optimized to process ∼9.6 × 10 5 times the concentrated ratio of collected bioaerosol samples, using a 3 min lysis time to extract ATP, and has a detection limit of ∼375 colony-forming units (CFUs)/mL with more than 30 days of stability for the immobilizedluciferase/luciferin detection unit supported by a glass-fiber conjugation pad. After the integration of all units, the ABMS achieved E. coli bioaerosol monitoring with continuous detection at 5 min intervals and a minimum detection limit of ∼130 CFU/m air 3 . Furthermore, the rapid responsivity and stable operation performance of the ABMS under test-bed conditions and during a field test demonstrated that the ABMS is capable of continuously monitoring bioaerosols in real-time with high sensitivity. The monitoring system developed here with immobilization strategies for bioluminescence reactions triggered by ATP extracted from collected bioaerosol samples using a simple heat-lysis method may help establish sustainable platforms to obtain stable signals for the real-time detection of bioaerosols on-site.

Bioaerosols, including infectious diseases such as COVID-19, are a continuous threat to global public safety. Despite their importance, the development of a practical, real-time means of monitoring bioaerosols has remained elusive. Here, we present a novel, simple, and highly efficient means of obtaining enriched bioaerosol samples. Aerosols are collected into a thin and stable liquid film by the unique interaction of a superhydrophilic surface and a continuous twophase centrifugal flow. We demonstrate that this method can provide a concentration enhancement ratio of ∼2.4 × 10 6 with a collection efficiency of ∼99.9% and an aerosol-into-liquid transfer rate of ∼95.9% at 500 nm particle size (smaller than a single bacterium). This transfer is effective in both laboratory and external ambient environments. The system has a low limit of detection of <50 CFU/m 3 air using a straightforward bioluminescence-based technique and shows significant potential for air monitoring in occupational and publichealth applications.

No abstract

After the WHO designated COVID-19 a global pandemic, face masks have become a precious commodity worldwide. However, uncertainty remains around several details regarding face masks, including the potential for transmission of bioaerosols depending on the type of mask and secondary spread by face masks. Thus, understanding the interplay between face mask structure and harmful bioaerosols is essential for protecting public health. Here, we evaluated the microbial survival rate at each layer of commercial of filtering facepiece respirators (FFRs) and surgical masks (SMs) using bacterial bioaerosols. The penetration efficiency of bacterial particles for FFRs was lower than that for SMs; however, the microbial survival rate for all tested masks was >13%, regardless of filtration performance. Most bacterial particles survived in the filter layer (44%-77%) (e.g., the core filtering layer); the outer layer also exhibited significant survival rates (18%-29%). Most notably, survival rates were determined for the inner layers (<1% for FFRs, 3%-16% for SMs), which are in contact with the respiratory tract. Our comparisons of the permeability and survival rate of bioaerosols in each layer will contribute to bioaerosol-face mask research, while also providing information to facilitate the establishment of a mask-reuse protocol.

No abstract