Studies on Photothermal Effect in Nanofluidic Channel Toward Ultrasensitive Detection of Nonfluorescent Molecules Using Differential Interference Contrast Thermal Lens Microscope

摘要

Thermal lens effect in nanofluidic channel was investigated by calculation and experiment. Recently, analytical chemistry has been rapidly miniaturized to micrometer and nanometer scale. In such small spaces, high sensitivity and versatility are required for detection techniques. Previously, our group has developed a differential interference contrast thermal lens microscope (DIC-TLM) to detect nonfluorescent molecules in nanofluidic channels smaller than wavelength of light. The DIC-TLM, which was based on light absorption and nonradiative relaxation followed by a change in refractive index, realized a sensitive determination of concentration of nonfluorescent molecules to date. However, heat transfer was remained as a problem to decrease sensitivity significantly. In this paper, the heat transfer was closely investigated by a computational method and the simulation results were compared with experimental result to discuss causes of the signal decrease and strategies to improve sensitivity.