High Sensitivity Detection of ATP Using Bioluminescence at An Optical Fiber End

We investigated the sensitivity of ATP detection based on bioluminescence at an optical fiber end where luciferase molecules were immobilized via silica-binding protein molecules. Luminescence was detected by an avalanche photodiode (APD), with coupling optics to make full use of the merits of compactness, high quantum efficiency, and low noise of the APD. The core diameter and the numerical aperture of the optical fiber, as well as the design of the coupling optics, were optimized so as to realize high photon-collection efficiency. A detection limit of about 10−10 M was obtained, which corresponds to 10−15 mol of ATP. A rough estimation shows that the photon count rate is still two orders of magnitude lower than that limited by diffusion or reaction processes, implying a possibility of further improvement of the sensitivity. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(9): 53–59, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10054