Electrochemical detection of the disease marker human chitinase-3-like protein 1 by matching antibody-modified gold electrodes as label-free immunosensors

Tissue inflammation, certain cardiovascular syndromes and the occurrence of some solid tumors are correlated with raised serum concentrations of human chitinase-3-like protein 1 (YKL-40), a mammalian chitinase-like glycoprotein, which has become the subject of current research. Here we report the construction and characterization of an electrochemical platform for label-free immunosensing of YKL-40. Details of the synthesis of YKL-40 and production of anti-YKL-40 immunoglobulin G (IgG) are provided and cross-reactivity tests presented. Polyclonal anti-YKL-40 IgG was immobilized on gold electrodes and the resulting immunosensors were operated in an electrochemical flow system with capacitive signal generation. The strategy offered a wide linear detection range (0.1 mu g/L to 1 mg/L) with correlation coefficients (R-2) above 0.99 and good sensitivity (12.28 +/- 0.27 nF/cm(2) per decade of concentration change). Additionally, the detection limit of 0.07 +/- 0.01 mu g/L was well below that of optical enzyme-linked immunosorbent assays (ELISAs), which makes the proposed methodology a promising alternative for YKL-40 related disease studies. (C) 2014 Elsevier B.V. All rights reserved.