Nonspecific particle-based method with two-photon excitation detection for sensitive protein quantification and cell counting.

摘要: A novel easy-to-use homogeneous method utilizing two-photon excitation (TPX) for quantification of proteins or counting eukaryotic cells in solution has been developed. This highly sensitive technique is based on the adsorption competition between sample and fluorescently labeled protein to micrometer-sized carboxylate modified polystyrene particles detection excited fluorescence. The was detected as a distinct fluorescence individual microparticles. Analyte interacted with particle surface reduced resulting decrease optimizations assay conditions were performed separately cell counting, principle confirmed microscopy imaging. allowed determination picogram quantities (1.2 μg/L) protein, three an average variation approximately 10% signal. sensitivity more than 500-fold improved from common most commercial methods. Moreover, dynamic range broad, 4 orders magnitude. comparable method. developed tolerates interfering agents such neutral detergents found lysate samples even at high concentrations. experimentally fairly simple allows expansion use TPX technology.