title: Extended nanofluidic immunochemical reaction with femtoliter sample volumes.
abstract: The growing need to optimize immunoassay performance driven by interest in analyzing individual cells has resulted in a decrease in the amount of sample required. Miniaturized immunoassays that use ultra-small femtoliter to attoliter sample volumes, a range known as the extended nanospace, can satisfy this analytical need; however, capturing every targeted molecule without loss in extended nanochannels for subsequent detection remains challenging. This is the first report of a successful extended nanofluidics-based quantitative immunochemical reaction capable of high capture efficiency using a femtoliter-scale sample volume. A novel patterning method using a photolithographic technique with vacuum ultraviolet light and low-temperature (100 °C) bonding enables patterning of functional groups for antibody immobilization before bonding, resulting in an immunochemical reaction space of only 86 fL. Reaction rate analyses indicate a decrease in the required sample volume to 810 fL and improvement in the limit of detection to 3 zmol, 5-6 orders of magnitude better than possible with the microfluidic immunoassay format. Highly efficient (near 100%) immunochemical reactions on a seconds time scale are possible due to the nm-scale diffusion length, which should be advantageous for the analysis of ultra-low-volume samples.
authors: Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan.
authors: Kentaro
authors: K
authors: Shirai
authors: Kazuma
authors: K
authors: Mawatari
authors: Takehiko
authors: T
authors: Kitamori
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized; D002417:Cattle; D007120:Immunochemistry / Q000379:methods*; D057230:Limit of Detection; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D036103:Nanotechnology; D011327:Printing; D059010:Single-Cell Analysis / Q000379:methods
chemical_list: D055910:Antibodies, Immobilized
keywords: extended nanospace; immunoassay; nanofluidics; surface patterning