A pinboard by
Nirmala Thomas

Ph.D. Student, Rutgers, the State University of New Jersey


Air borne ions effect from a radioactive source and charger section of novel bioaerosol sampler

Personal electrostatic bioaerosol sampler (PEBS) has been recently developed at Rutgers University to assess exposure to airborne microorganisms. It has been shown to effectively collect airborne biological particles while producing very low ozone concentrations. The key features of PEBS are the charging section made up of a tungsten wire-to-stainless steel wire configuration and a removable, superhydrophobic coated, dual-side collection section. This study evaluated the change in microbial viability and culturability due to airborne ions interactions before the collection section of PEBS. Biological particles were tested under three conditions: 1) particles were charge-neutralized by a radioactive Po-210 source and then those that retained any amount of were electrostatically collected, 2) particles were not neutralized and then electrostatically collected, and 3) particles were neutralized, imparted positive ions and then collected electrostatically.

Pure cultures of gram-positive bacteria Bacillus atrophaeus and fungal spores Penicillium chrysogenum were aerosolized and conveyed into the test chamber for 10 min in triplicates. Collection efficiency of PEBS was also compared to an active control (BioSampler by SKC, Inc.). Total bacteria and fungi were counted by epifluorescent microscopy and hemocytometer chamber. Viable bioaerosols were detected using bioluminescence Adenosine Triphosphate and Thiazole Orange/Propidium Iodide cell viability assays. Culturable bacteria and fungi were determined by plating aliquots on nutrient agar and malt extract agar plates. For bacteria, the viability was 64% in the absence of ions while reducing to 52% when charge-neutralized and 58% with imparted positive ions. Culturability was higher in the absence of ions but not statistically different to the other conditions (p>0.05). For fungi, the viability and culturability were not different in the three conditions (p>0.05).
These results suggest that the airborne ion emissions from PEBS did not affect fungal spores but decreased viability and culturability for sensitive bioaerosols. Future tests would include extended sampling time and outdoor testing with active Button Sampler and BioSampler at standard flow rates.


Direct analysis of airborne mite allergen (Der f1) in the residential atmosphere by chemifluorescent immunoassay using bioaerosol sampler.

Abstract: Dermatophagoides farinae allergen (Der f1) is one of the most important indoor allergens associated with allergic diseases in humans. Mite allergen Der f1 is usually associated with particles of high molecular weight; thus, Der f1 is generally present in settled dust. However, a small quantity of Der f1 can be aerosolized and become an airborne component. Until now, a reliable method of detecting airborne Der f1 has not been developed. The aim of this study was to develop a fiber-optic chemifluorescent immunoassay for the detection of airborne Der f1. In this method, the Der f1 concentration measured on the basis of the intensity of fluorescence amplified by an enzymatic reaction between the labeled enzyme by a detection antibody and a fluorescent substrate. The measured Der f1 concentration was in the range from 0.49 to 250 ng/ml and a similar range was found by enzyme-linked immunosorbent assay (ELISA). This method was proved to be highly sensitive to Der f1 compared with other airborne allergens. For the implementation of airborne allergen measurement in a residential environment, a bioaerosol sampler was constructed. The airborne allergen generated by a nebulizer was conveyed to a newly sampler we developed for collecting airborne Der f1. The sampler was composed of polymethyl methacrylate (PMMA) cells for gas/liquid phases and some porous membranes which were sandwiched in between the two phases. Der f1 in air was collected by the sampler and measured using the fiber-optic immunoassay system. The concentration of Der f1 in aerosolized standards was in the range from 0.125 to 2.0 mg/m(3) and the collection rate of the device was approximately 0.2%.

Pub.: 15 Apr '14, Pinned: 28 Jun '17

Evaluation of sampling methods for toxicological testing of indoor air particulate matter.

Abstract: There is a need for toxicity tests capable of recognizing indoor environments with compromised air quality, especially in the context of moisture damage. One of the key issues is sampling, which should both provide meaningful material for analyses and fulfill requirements imposed by practitioners using toxicity tests for health risk assessment. We aimed to evaluate different existing methods of sampling indoor particulate matter (PM) to develop a suitable sampling strategy for a toxicological assay. During three sampling campaigns in moisture-damaged and non-damaged school buildings, we evaluated one passive and three active sampling methods: the Settled Dust Box (SDB), the Button Aerosol Sampler, the Harvard Impactor and the National Institute for Occupational Safety and Health (NIOSH) Bioaerosol Cyclone Sampler. Mouse RAW264.7 macrophages were exposed to particle suspensions and cell metabolic activity (CMA), production of nitric oxide (NO) and tumor necrosis factor (TNFα) were determined after 24 h of exposure. The repeatability of the toxicological analyses was very good for all tested sampler types. Variability within the schools was found to be high especially between different classrooms in the moisture-damaged school. Passively collected settled dust and PM collected actively with the NIOSH Sampler (Stage 1) caused a clear response in exposed cells. The results suggested the higher relative immunotoxicological activity of dust from the moisture-damaged school. The NIOSH Sampler is a promising candidate for the collection of size-fractionated PM to be used in toxicity testing. The applicability of such sampling strategy in grading moisture damage severity in buildings needs to be developed further in a larger cohort of buildings.

Pub.: 30 Aug '16, Pinned: 28 Jun '17

Miniature PCR Based Portable Bioaerosol Monitor Development.

Abstract: A portable bioaerosol monitor is highly demanded technology in many areas including air quality control, occupational exposure assessment and health risk evaluation, environmental studies and, especially, in defence and bio-terrorism applications. Our recent groundwork allowed us to formulate the concept of a portable bioaerosol monitor, which ought to be light, user friendly, reliable and capable of detecting airborne pathogens within 1 -1.5 hours at the spot.Conceptually, the event of bioaerosol concentration burst is determined by triggers, commencing representative air sampling with sequential real-time PCR confirmation of the targeted microorganism presence in the air. To minimise the reagent consumption and idle running of the technology, an event of the bioaerosol burst is confirming by three parameters: aerosol particles size, concentration and composition. The only particles sizes above 200 nm attract interest towards the bioaerosol. The only elevated aerosol concentration above the threshold (background aerosol concentration) is a signal for analytical procedure commencement. The combination of our previously developed personal bioaerosol sampler, aerosol particle counter based trigger and portable real-time PCR device formed the basis of bioaerosol monitoring technology. The portable real-time PCR device was advanced to provide the internally controlled detection, significantly reducing false positive alarms.The technique is capable to detect selected airborne microorganisms at a spot within 30 - 80 minutes, depending on the particular strain genome organisation.Due to recent outbreaks of infectious airborne diseases and the continuing threat of intentionally-released bioaerosol attacks, investigations into the possibility of early and reliable detection of pathogenic microorganisms in the air is becoming increasingly important. The proposed technology consisting of a bioaerosol sampler, technology trigger and PCR device is capable to detect selected airborne microorganisms at a spot within short time period. This article is protected by copyright. All rights reserved.

Pub.: 07 Oct '16, Pinned: 28 Jun '17