MAIN RESEARCH DIRECTIONS

SELECTED RESEARCH PROJECTS (under revision)

 For more information about these and other projects, please contact Dr. G. Mainelis mainelis@envsci.rutgers.edu

“Evaluation of Portable Samplers for Viable Bioaerosols”

Recently, portable bioaerosol samplers have been gaining in popularity as tools for microbial monitoring in occupational and residential environments. However, very little data are available about their performance and it is not known whether these samplers follow any health-related sampling conventions and whether their data could be related to personal exposures. This project focuses on a systematic investigation of portable bioaerosol samplers’ performance in the laboratory and field environments. Performance of the portable impactors is compared against the Andersen-type impactor and the Button Aerosol Sampler equipped with gelatin filter.

 Related publications:

1.                  Yao, M.^# and Mainelis, G.* (2006a) Analysis of Portable Impactor Performance for Enumeration of Viable Bioaerosols, Journal of Occupational and Occupational Hygiene, submitted.

2.                  Yao, M.^# and Mainelis, G.* (2006b) Use of Portable Microbial Samplers for Estimating Inhalation Exposure to Viable Biological Agents, Journal of Exposure Science and Environmental Epidemiology, doi: 10.1038/sj.jea.7500517.

3.                  Yao, M.^# and Mainelis, G.* (2006c) Effect of Physical and Biological Parameters on Enumeration of Bioaerosols by Portable Microbial Impactors, Journal of Aerosol Science, published online, doi:10.1016/j.jaerosci.2006.06.005.

4.                  Yao, M.^# and Mainelis, G.* (2006d) Investigation of Cutoff Sizes and Collection Efficiencies of Portable Microbial Samplers, Aerosol Science and Technology, 40(8): 595-606. 

”Design and Evaluation of Advanced Electrostatic Sampler for Total Bioaerosols”

Integration of bioaerosol sampling methods with modern analysis techniques, such as the polymerase chain reaction (PCR) as well as our ability to detect low concentrations of airborne agents require samplers that are able not only to efficiently collect the biological particles, but also to concentrate them in small amounts of fluids. In this research, we are developing a novel bioaerosol sampler, 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. This new sampling concept allows achieving very high sample concentration rates (up to 1 million and higher) and could be applied to detect low concentrations of bioaerosols in various environments.

 Related publications:

Han, T.^# and Mainelis, G.* (2008) Design and Development of an Electrostatic Sampler for Bioaerosols with High Concentration Rate, Journal of Aerosol Science, 12: 1066-1078.

Han, T.^#, An, H.R.^# and Mainelis, G.* (2010) Performance of an Electrostatic Precipitator with Superhydrophobic Surface when collecting Airborne Bacteria, Aerosol Science and Technology, 44:339-348. Abstract.

Han, T.^#, Nazarenko, Y. ^#, Lioy, P.J., and Mainelis, G.* (2011) Collection Efficiencies of An Electrostatic Sampler With Superhydrophobic Surface For Fungal Bioaerosols, Indoor Air, 21:110-120. Abstract

“The Effectiveness of Bubble Aerosol Generator for Sensitive Bacteria”

 A variety of bioaerosol studies require reliable generation of biological aerosols over extended periods of time. Although pneumatic nebulization is widely applied, it has been shown to injure and fragment the organisms due to shear stress and repeated “recycling” of microbial suspension. We have designed and analyzed a new particle generator that utilizes a bursting bubble principle and eliminates carrier fluid reuse. When this Liquid Sparging Aerosolizer (LSA) was applied for sensitive bacteria P. fluorescens, their viability virtually did not change after 90 minutes of continuous aerosolization, while there was a 50% loss in viability after pneumatic aerosolization. We are currently investigating application of this technology for other sensitive microorganisms.

 Related Publications:

Mainelis, G.*, Berry, D.^#, An, H.R.^#, Yao, M.^#, DeVoe, K., Fennell, D.E., and Jaeger, R. (2005) Performance and Design of a Single-Pass Bubbling Bioaerosol Generator, Atmospheric Environment, 39(19): 3521-3533.

 “Application of electrostatic techniques for bioaerosol collection”

 Commonly used inertia-based bioaerosol samplers are known to underestimate microorganism presence due to the damage to sensitive species. In a search for more advanced sampling techniques we have been investigating application of electrostatic precipitation for bioaerosol collection. We have recently determined a range of conditions when the electrostatic fields could be used either to collect the microorganisms without damage, or to inactivate them. Although literature already describes application of pulsed electrical fields to inactivate the microorganisms, our study was the first one to show that static electrical fields could also be used for microorganism inactivation.

We have recently investigated a hypothesis that innate electrical charge carried by the ambient microorganisms should be sufficient for their collection. To test this hypothesis we built a new electrostatic collector featuring no external charging and compared it with an Andersen-type impactor in indoor and outdoor environments. This new method consistently enumerated more airborne bacteria and fungi, sometimes by as many as 5-9 times. This study was the first one to show that innate charges on bioaerosols are sufficient for their collection by electrostatic technique.

Related publications:

1.      Yao, M.^# and Mainelis, G.* (2006e) Utilization of Natural Electrical Charge on Airborne Microorganisms for their Collection by Electrostatic Means, Journal of Aerosol Science, 37(4): 513–527.

2.      Yao, M.^#, Mainelis, G.*, and An, H.R.^# (2005) Inactivation of Microorganisms using Electrical Fields, Environmental Science and Technology, 39(9): 3338-3344.