An interference-free and rapid electrochemical lateral-flow immunoassay for one-step ultrasensitive detection with serum.
Point-of-care testing (POCT) of biomarkers in clinical samples is of great importance for rapid and cost-effective diagnosis. However, it is extremely challenging to develop an electrochemical POCT technique retaining both ultrasensitivity and simplicity. We report an interference-free electrochemical lateral-flow immunoassay that enables one-step ultrasensitive detection with serum. The electrochemical-chemical-chemical (ECC) redox cycling combined with an enzymatic reaction of an enzyme label is used to obtain high signal amplification. The ECC redox cycling involving Ru(NH3)6(3+), enzyme product, and tris(3-carboxyethyl)phosphine (TCEP) depends on pH, because the formal potentials of an enzyme product and TCEP increase with decreasing pH although that of Ru(NH3)6(3+) is pH-independent. With consideration of the pH dependence of ECC redox cycling, a noble combination of enzyme label, substrate, and product [β-galactosidase, 4-amino-1-naphthyl β-D-galactopyranoside, and 4-amino-1-naphthol, respectively] is introduced to ensure fast and selective ECC redox cycling of the enzyme product along with a low background level. The selective ECC redox cycling at a low applied potential (0.05 V vs. Ag/AgCl) minimizes the interference effect of electroactive species (L-ascorbic acid, acetaminophen, and uric acid) in serum. A detection limit of 0.1 pg mL(-1) for troponin I is obtained only 11 min after serum dropping without the use of an additional solution. Moreover, the lateral-flow immunoassay is applicable to the analysis of real clinical samples.
Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea. hyang@pusan.ac.kr.
Md Rajibul
MR
Akanda
Hyou-Arm
HA
Joung
Vellaiappillai
V
Tamilavan
Seonhwa
S
Park
Sinyoung
S
Kim
Myung Ho
MH
Hyun
Min-Gon
MG
Kim
Haesik
H
Yang
D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation; D055664:Electrochemical Techniques / Q000191:economics / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000191:economics / Q000295:instrumentation*; D057230:Limit of Detection; D019095:Point-of-Care Systems / Q000191:economics; D019210:Troponin I / Q000097:blood*
D019210:Troponin I