Chemiluminescence detection of protein in capillary electrophoresis using aptamer-functionalized gold nanoparticles as biosensing platform

Highly sensitive and selective detection of disease-related proteins play critical roles in clinical practice and diagnostic assays. Herein, we proposed a highly selective and ultrasensitive chemiluminescence (CL) method for protein detection in capillary electrophoresis (CE) using aptamer-functionalized gold nanoparticles (AuNPs) as biosensing platform. In this protocol, AuNPs were synthesized and conjugated with aptamer to form AuNPs-aptamer. Using thrombin and thrombin binding aptamer as an initial proof-of-concept recognization pair, AuNPs-aptamer was linked to thrombin to produce an AuNPs-aptamer-thrombin complex. The resulted complex and unbound AuNPs-aptamer were separated in CE and detected with luminol-H2O2 CL system. The developed strategy produced an ultrasensitive detection of thrombin down to 13.5 fmol/L (S/N = 3) with a linear range from 0.033 to 66.0 pmol/L The application of the present protocol was demonstrated by analyzing thrombin in human plasma samples with the recoveries of 87.6-116.8%. This novel strategy has many outstanding merits including high specificity of aptamer, excellent catalysis behavior of AuNPs, high sensitivity of CL detection, and high separation efficiency of CE. (C) 2014 Elsevier B.V. All rights reserved.