Gold-nanostructured immunosensor for the electrochemical sensing of biotin based on liposomal competitive assay.
This work describes the development of a cost-effective, easy-to-use, portable immunoanalytical platform technology with sufficient sensitivity for use in the detection of physiologically important targets. Biotin, also known as vitamin H, was selected as the model analyte. The detecting system employs biotin-tagged, potassium ferrocyanide-encapsulated liposomes as the signal amplifier and PAH (poly allylamine hydrochloride)-modified, nanosized-Au particles assembled screen-printed electrode (nanoAu-SPE) as the working electrode. The diagnostic procedures are based on selective immunoanalytical recognitions and sensitive electrochemical detection. The model analyte biotin was determined based on a "competitive-type" immunoassay in which competition occurs between the analyte biotin and potassium ferrocyanide-encapsulated, biotin-tagged liposomes for a limited number of anti-biotin antibody binding sites, which were immobilized on the PAH/nanoAu/SPE surface. The nanostructured Au SPE surface was covalently bonded to the PAH layer, which subsequently interacted with anti-biotin antibodies. The ferrocyanide released from ruptured bound-liposomes was finally measured using square-wave voltammetry. The calibration curve for biotin had a linear range of 10(-11)-10(-2) M, covering nine orders of magnitude. The detection limit of this immunodetecting system was as low as 9.1 pg of biotin (equivalent to 4.5/microL of 8.3 x 10(-9) M).
BioAnalytical Lab, Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Ja-An Annie
JA
Ho
Je-Kuan
JK
Chiu
Jia-Cherng
JC
Hong
Chun-Cheng
CC
Lin
Kuo-Chu
KC
Hwang
Jih-Ru Reuben
JR
Hwu
D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D001710:Biotin / Q000032:analysis* / Q000138:chemical synthesis / Q000276:immunology; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D005295:Ferrocyanides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D008081:Liposomes / Q000138:chemical synthesis / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D011073:Polyamines / Q000138:chemical synthesis / Q000737:chemistry; D012680:Sensitivity and Specificity
D000906:Antibodies; D005295:Ferrocyanides; D008081:Liposomes; D011073:Polyamines; C063994:polyallylamine; D001710:Biotin; D006046:Gold; C031835:potassium ferrocyanide