Performance of an Electrostatic Precipitator with Superhydrophobic Surface when Collecting Airborne Bacteria

Abstract

Modern bioaerosol sampling and analysis techniques that enable rapid detection of low bioagent concentrations in various environments are needed to help us understand the causal relationship between adverse health effects and bioaerosol exposures and also to enable the timely biohazard detection in case of intentional release.We have developed a novel bioaerosol sampler, an electrostatic precipitator with superhydrophobic surface (EPSS), where a combination of electrostatic collection mechanism with superhydrophobic collection surface allows for efficient particle collection, removal, and concentration in water droplets as small as 5 µL. The sampler's performance at different sampling flow rates and sampling times was tested with two common bacteria: Pseudomonas fluorescens and Bacillus subtilis. The collection efficiency was determined using the traditional method of microscopic counting as well as the whole-cell quantitative real-time polymerase chain reaction assay (QPCR). The tests indicated that the new sampler achieves collection efficiency as high as 72%. A combination of the satisfactory collection efficiency and the small collecting water droplet volumes allowed achieving sample concentration rates that exceed 1 × 10 6 . In addition, the collection efficiency for both bacteria obtained by the two different methods was not statistically different, indicating the sampler's compatibility with the PCR-based sample analysis techniques. In addition, the whole-cell QPCR does not require DNA extraction prior to the PCR reaction which offers faster sample processing.Very high concentration rates achieved with the new sampler as well as its compatibility with the QPCR methodology point toward its suitability for detecting low concentrations of airborne bacterial agents in various environments.

Investigation of a New Electrostatic Sampler for Concentrating Biological and Non-Biological Aerosol Particles

“…However, since the sampler is able to perform an efficient collection of 0.3-0.35 μm particles, a wider range of airborne biological agents should be collectible, ranging from viruses to fungi. Following Han's (2008Han's ( , 2010 investigations, it was shown that transfer of biological particles is highly dependant on the composition and volume of the rinsing buffer, while best results were obtained with SDS.…”

“…According to the rinsing protocol, the collection efficiency obtained by plate counting in the present study ranges from 57 to 94% when at least 15 ml of liquid is used. Such a volume is commonly used in samplers such as the All Glass Impinger 30 (ACE Glass), the BioSampler R (SKC) and the Coriolis R (Bertin) but it is much higher than volumes used by Han (2008Han ( , 2010. The amount used therefore is a compromise between the recovery efficiency and the sample volume.…”

“…Han and Mainelis (2008) and Han et al (2010) highlighted that recovery efficiency depends on the particles and the rinsing procedure used, achieving a collection efficiency of 65 ± 7% determined by microscopy and 54 ± 3% determined by whole-cell QPCR for B. subtilis. According to the rinsing protocol, the collection efficiency obtained by plate counting in the present study ranges from 57 to 94% when at least 15 ml of liquid is used.…”

“…Yao demonstrated that electrostatic sampling could achieve culturable bioaerosol concentration levels as much as nine times higher than the BioStage impactor (Yao and Mainelis 2006) and five to ten times higher airborne allergen and toxin concentration levels than the BioSampler (Yao et al 2009). High concentration rates were also obtained with a smart implementation of the Lotus effect (Barthlott and Neinhuis 1997;Feng et al 2002) with an ultra hydrophobic surface (Han and Mainelis 2008;Han et al 2010). Unfortunately, while electrostatic precipitators (ESP) used as air cleaners work at high flow rates, most of the aforementioned studies are based on devices using a lower flow rate (Table 1) and are therefore not directly comparable.…”

Analysis of Culturable Bacterial and Fungal Aerosol Diversity Obtained Using Different Samplers and Culturing Methods

“…Their results indicated that the RCS High Flow obtained lower culturable counts than that of the BioSampler due to its higher desiccation factors ). Among various bioaerosol samplers, the electrostatic sampler is increasingly being applied to detect biological aerosols (Yao and Mainelis 2006c;Yao et al 2009b;Han et al 2010). It was shown that when the electrostatic sampler was used, the culturable bioaerosol concentrations could be 5-9 times higher than those obtained by the BioStage impactor (Yao and Mainelis 2006c).…”