Evaluation on the use of reactive dye-modified polylysine as the biomarker in immunochromatographic test application.

Wei-Feng Chang, Shwu-Jinng Wang, Sin-Fang Lai, Chwen-Jen Shieh, Kuang-Pin Hsiung, Yung-Chuan Liu

Index: Anal. Biochem. 411(2) , 236-40, (2011)

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Abstract

An improved dye immunochromatographic test (DICT) using polylysine (PL) as conjugate spacer loading dye molecules to enhance chromophor color intensity with the potential of a simultaneous multicolored assay has been developed. To construct this new effective chromophor, a dyeing process coupling a reactive dye, Procion Blue MX-7RX (PB7RX), with PL of different molecular weights was performed. The optimal conjugate condition between PB7RX and PL was studied. It showed that under the optimized dyeing conditions, a PL molecular weight of 189.4 kDa and a molar ratio (mol dye/mol amine group in PL) of 1.5 were obtained. The resulting dyed PL chromophor, used as both a spacer and a color intensifier, was further labeled to a model antibody, anti-human serum albumin (anti-HSA), to build a PB7RX-PL-anti-HSA (PPA) conjugate. The PPA obtained in this way generated the highest color intensity of 19,455 assayed by immunochromatographic test strip under densitometer scanning. A competitive DICT for determination of HSA was carried out. A linear range between 0 and 18.77 μg/ml with a detection limit of 0.49 μg/ml was observed. A test for using dyed PL chromophors as biomarkers was also performed to demonstrate the feasibility of a multianalyte immunoassay.Copyright © 2010 Elsevier Inc. All rights reserved.