Microfluidic chip-based electrochemical immunoassay for hippuric acid.
Urinary hippuric acid (HA), of molecular weight 180 Da, is one of the major metabolites in toluene-exposed humans and is a major biological indicator. Simple and ubiquitous monitoring of exposure to toluene is very important in occupational health care, and a microfluidic chip-based electrochemical immunoassay for rapid and quantitative detection of HA in human urine is proposed in this paper. The system employs a conjugate of ferrocene (Fc) and hippuric acid (HA). The competition between hippuric acid (HA) and the ferrocene-hippuric acid complex (Fc-Lys-HA) to bind with a HA antibody coated onto polybeads generated electrical signals proportional to the HA concentration in the range of 0-40 mg mL(-1). All the complicated HA detection processes were integrated on the single microfluidic platform. The quantitative advantages of our HA detection chip are as follows: (1) the total chip size was reduced to 3.0 x 2.0 x 0.5 cm and is small enough to be portable, (2) the assay time took 1 min, and is shorter than that of conventional electrochemical HA immunoassay systems (about 20 min) and (3) 40 microL of the sample solution was enough to detect HA in the range of 0-40 mg mL(-1), which is enough range to be used for the point-of-care system. In addition, we suggest the improved chip-based HA assay method by the combination of electrochemical and enzymatic amplification processes for the detection of greater electrical signals. The sensitivity of the combined method was increased about three times compared to that of the non-enzymatic process.
Yoo
Sung Ju
SJ
Department of Chemistry, College of Advanced Science, Dankook University, Anseo-dong, Cheonan 330-714, Republic of Korea.
Choi
Young Bong
YB
Ju
Jong Il
JI
Tae
Gun-Sik
GS
Kim
Hyug Han
HH
Lee
Sang-Hoon
SH
D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods; D005296:Ferrous Compounds; D006626:Hippurates / Q000737:chemistry*; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D008239:Lysine / Q000737:chemistry; D000075163:Metallocenes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D015394:Molecular Structure
D005296:Ferrous Compounds; D006626:Hippurates; D000075163:Metallocenes; D008239:Lysine; C030514:hippuric acid; C004998:ferrocene