Article abstract

Nature Biotechnology 18, 548 - 550 (2000)

A new microvolume technique for bioaffinity assays using two-photon excitation

Pekka Hänninen1, Aleksi Soini1, Niko Meltola1, Juhani Soini1, Jori Soukka1 & Erkki Soini1

Bioaffinity binding assays such as the immunoassay are widely used in life science research. In an immunoassay, specific antibodies are used to bind target molecules in the sample, and quantification of the binding reaction reveals the amount of the target molecules. Here we present a method to measure bioaffinity assays using the two-photon excitation of fluorescence. In this method, microparticles are used as solid phase in binding the target molecules. The degree of binding is then quantified from individual microparticles by use of two photon excitation of fluorescence. We demonstrated the effectiveness of the method using the human alpha-fetoprotein (AFP) immunoassay, which is used to detect fetal disorders. The sensitivity and dynamic range we obtained with this assay indicate that this method can provide a cost-effective and simple way to measure various biomolecules in solution for research and clinical applications.

two-photon excitationimmunoassaymicrovolume detectionoptical trappingmicrochip laserTop
  1. Laboratory of Biophysics, Institute of Biomedicine, University of Turku,P.O. Box 123, 20521 Turku, Finland.

Correspondence to: Pekka Hänninen1 e-mail: