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Proceedings Paper

Investigation of photoacoustic spectroscopy for biomolecular detection
Author(s): Saher M. Maswadi; Randolph D. Glickman; Norman Barsalou; Rowe W. Elliott
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Paper Abstract

We are developing a non- or minimally-invasive method for detecting and measuring specific drugs and biomolecules in vivo using photoacoustic spectroscopy (PAS). This pilot study investigated the feasibility of detecting the concentration of certain drugs in the vitreous or aqueous of the eye. As a prototype for using PAS for molecular detection in vivo, the technique was applied to the detection in a surrogate eye, of drugs with known optical spectrum such as Trypan Blue, Rose Bengal, and Amphotericin B (AB), at concentrations as low as 1 μg/ml. Chopped CW, or short pulse, Q-switch lasers, were used as pumping sources to generate ultrasonic photoacoustic signals in an ocular phantom containing the drug solutions. In addition to an ultrasonic hydrophone, the photothermal deflection technique (PhDT), a non-contact optical method with high sensitivity and fast response, were used to record the photoacoustic signals. The data from both detectors were compared over a range of drug concentrations. The photoacoustic signal generated from the retina was used as a reference, to measure the attenuation of light through drug solutions of different concentrations in the ocular phantom. The results indicated that photoacoustic spectroscopy is feasible in ocular phantoms incorporating ex vivo ocular tissue. The signals recorded using PAS were to be found to be linearly dependent on drug concentration, as predicted by theory. The photoacoustic method was found to be sensitive to drug concentrations as low as 1 μg/ml, a clinically relevant concentration for many drugs. Future work will be directed at adapting this method for in vivo measurement, and enhancing its sensitivity by using a tunable laser as the pump source.

Paper Details

Date Published: 7 March 2006
PDF: 10 pages
Proc. SPIE 6138, Ophthalmic Technologies XVI, 61380V (7 March 2006); doi: 10.1117/12.674408
Show Author Affiliations
Saher M. Maswadi, Univ. of Texas Health Science Ctr. at San Antonio (United States)
Randolph D. Glickman, Univ. of Texas Health Science Ctr. at San Antonio (United States)
Norman Barsalou, Naval Health Research Ctr. (United States)
Rowe W. Elliott, Naval Health Research Ctr. (United States)


Published in SPIE Proceedings Vol. 6138:
Ophthalmic Technologies XVI
Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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