Abstract
Nonlabeled protein was detected at zeptomole (zmol) order with an optical path length of 900 nm using UV differential interference contrast thermal lens microscope (UV-DIC-TLM). The principle of DIC-TLM, which is based on wave optics, allowed sensitive detection in a nanofluidic channel comparable to the wavelength of light. By introducing UV excitation into the DIC-TLM, detection of nonlabeled protein was realized in a nanofluidic channel. This technology is promising for analytical devices using nanospace including chromatography and extremely small volume analysis such as single cell analysis.