Biomedical engineers from the University of Washington in St. Louis have developed a novel technique to image oxygen levels in individual cells in real-time. The technique, called photoacoustic flowoxigraphy, uses two laser pulses of different frequencies fired 20 microseconds apart to identify the color of a red blood cell, which identifies it’s oxygenation at a given instant in time.
As shown in the video below, the researchers can image the cells in a given capillary segment at a rate of 200Hz. By monitoring the cells’ color change as they traverse the capillary, the researchers can determine the rate of oxygen delivery over a given time frame or capillary distance.
Prof. Wang and colleagues have published their technique in detail in the latest edition of The Proceedings of the National Academy of Sciences. According to the paper, the team successfully quantified multiple single red blood cell functional parameters, including total hemoglobin concentration, oxygen saturation, gradient, flow speed, and oxygen release rate, simultaneously in real time.
Prof. Lihong Wang, the lead developer of the technology, envisions a number of applications for the technology from monitoring changes in oxygen metabolism due to diabetes or cancer to monitoring the effects of therapeutic interventions on oxygen metabolism. The team hope to license their technology so that some of these applications may be realized.
Article in PNAS: Single-cell label-free photoacoustic flowoxigraphy in vivo