Infrared biosensors using hydrophobic chalcogenide fibers sensitized with live cells

Chalcogenide glass fibers are used to perform remote infrared analysis in a fiber evanescent wave spectroscopy system (FEWS). Spectral analysis of a series of organic species demonstrates that the detection signal of non-polar species is enhanced by up to 60% relative to that of water. Contact angle measurements of the organic liquid/glass interaction strength shows that the spectral enhancement is the result of glass surface hydrophobicity. The greater interaction of non-polar species with the chalcogenide surface leads to a concentration gradient of the organic species at the glass surface where the evanescent wave is most intense. This results in selective detection of non-polar organic species in aqueous solution using FEWS. This behavior is beneficial for the detection of microorganism by FEWS and is used to design bio-optic sensors based on monitoring the response of live cells to toxins by detecting change in their infrared spectrum. This technique permits observation of disruption induced in living mammalian cells by at least two different types of toxicants. It is shown that it is possible to distinguish between the effect of a genotoxic agent (which damage nucleic acids) and a cytotoxic agent (which damages other cellular components) based on the cell's IR response. (c) 2005 Elsevier B.V. All rights reserved.