H. Shiku et al., DUAL IMMUNOASSAY OF HUMAN CHORIONIC-GONADOTROPIN AND HUMAN PLACENTAL-LACTOGEN AT A MIOCROFABRICATED SUBSTRATE BY SCANNING ELECTROCHEMICAL MICROSCOPY, Journal of electroanalytical chemistry [1992], 438(1-2), 1997, pp. 187-190
A dual immunoassay of human chorionic gonadotropin (HCG) and human pla
cental lactogen (HPL) at a microfabricated substrate was studied using
scanning electrochemical microscopy (SECM). Anti-HCG and anti-HPL wer
e microspotted on 50 X 50 mu m(2) raised flat squares separated from e
ach other by 150 mu m at a glass substrate. A 10 mu l sample solution
containing HCG and/or HPL was then dropped onto the substrate followed
by treatment with a solution of horseradish peroxidase (HRP)-labeled
anti-HCG and HRP-labeled anti-HPL The SECM measurements were carried o
ut at 0.05 V vs. Ag/AgCl in the presence of ferrocenylmethanol (FMA) a
nd H2O2 to detect FMA(+) generated by the HRP reaction. The SECM image
s of the substrates showed clearly the large response areas which corr
esponded to the squares with HCG and/or HPL. The detection limits were
0.1 IU ml(-1) for HCG and 3 ng ml(-1) for HPL. (C) 1997 Elsevier Scie
nce S.A.