Fingerprinting individual bio-nanoparticles by interferometric photothermal microscopy (Conference Presentation)

Chemical characterization of biological specimens in the mid-infrared (IR) window plays a central role in the analysis of their functionalities. Although recent advances in mid-IR microscopy have demonstrated detection of the sample’s chemical contrast at a sub-micron resolution using a visible probe beam, they have limited sensitivity at high-throughput. To overcome this limit, we employ wide-field interferometric microscopy to detect the minute change in the optical path induced by mid-IR absorption. Our technique enables high-speed fingerprinting of more than thousands of sub-200 nm nanoparticles at once. This method paves the way for high-throughput, ultrasensitive, and label-free chemical imaging of individual bio-nanoparticles at sub-micron resolution.