Student Research: Lauren Dunbar

, Occupational & Environmental Exposure Sciences (OEES), 2009
Faculty Advisor: John Meschke

Endotoxin Collection and Electrochemical Detection Method for Use in Bioaerosol Personal Sampling Device


The potential health effects of bioaerosols are a concern in many environmental and occupational settings. Endotoxin, or lipopolysaccharide, is a component of the outer membrane of Gram-negative bacteria. Studies have shown that inhaled endotoxin may result in increased asthma, airway irritation, and allergic responses. These are of particular interest in occupational settings such as dairy farms, textile plants, and grain processing. The current method for occupational bioaerosol sampling involves collection on glass fiber filters for an entire workday. A novel collection device with an aerodynamic lens inline with a p-trap impactor has been developed and tested for collection efficiency. In parallel, a novel electrochemical detection technique has been developed to quantify endotoxin concentration.

A novel electrochemical detection technique has been shown to be as sensitive as the limulus amebocyte lysate (LAL) assay, the gold standard for the quantification of endotoxin. In the new technique, endotoxin binds to a recombinant protein that cleaves a substrate with a serine protease to yield charged para-nitroanaline. Fast scan cyclic voltammetry measures the release of pNA using a screen-printed electrode. In this study, this detection technique is applied to small concentrations and volumes on a microfludic card. The reproducibility of the electrochemical detection in environmental samples is compared with the LAL assay. The electrode is shown to demonstrate concentrate dependence in the range of 0.05 EU/mL to 50 EU/ml. This is a promising detection device for field measurements of aerosolized endotoxin in real time.