Investigation of photoacoustic spectroscopy for biomolecular detection

Saher M. Maswadi, Randolph D. Glickman, Norman Barsalou, Rowe W. Elliott

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationOphthalmic Technologies XVI
StatePublished - 2006
EventOphthalmic Technologies XVI - San Jose, CA, United States
Duration: Jan 21 2006Jan 24 2006

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherOphthalmic Technologies XVI
Country/TerritoryUnited States
CitySan Jose, CA


  • Biomolecular detection
  • Hydrophone
  • Laser
  • Ocular phantom
  • Photo-acoustic
  • Photothermal deflection technique
  • Retina
  • Spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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