A Sensitive Electrochemical Immunosensor for α‐Fetoprotein Detection with Colloidal Gold‐Based Dentritical Enzyme Complex Amplification

Abstract

A sensitive and specific electrochemical immunosensor was developed with a-fetoprotein (AFP) as the model analyte by using gold nanoparticle label for enzymatic catalytic amplification. A self-assembled monolayer membrane of mercaptopropionic acid (MPA) was firstly formed on the electrode surface through gold-sulfur interaction. Monoclonal mouse anti-human AFP was covalently immobilized to serve as the capture antibody. In the presence of the target human AFP, gold nanoparticles coated with polyclonal rabbit anti-human AFP were bound to the electrode via the formation of a sandwiched complex. With the introduction of goat anti-rabbit IgG conjugated with alkaline phosphatase, the dentritical enzyme complex was formed through selective interaction of the secondary antibodies with the colloidal gold-based primary antibody at the electrode, thus affording the possibility of signal amplification for AFP detection. Current response arising from the oxidation of enzymatic product was significantly amplified by the dentritical enzyme complex. The current signal was proportional to the concentration of AFP from 1.0 ng mL À1 to 500 ng mL À1 with a detection limit of 0.8 ng mL À1. This system could be extended to detect other target molecules with the corresponding antibody pairs.

Alzheimer’s disease: Development of a sensitive label-free electrochemical immunosensor for detection of amyloid beta peptide

“…Thus, 5 mM was considered the most favorable concentration of MPA. The optimized conditions are in accordance with the values found in literature as periods of incubation ranging from 30 min-12 h and MPA concentrations ranging from 0.1-10 mM were found [12,[33][34][35][36][37][38].…”

Graphene and Nanogold‐Functionalized Immunosensing Interface with Enhanced Sensitivity for One‐Step Electrochemical Immunoassay of Alpha‐Fetoprotein in Human Serum

“…AFP is elevated in the malignant diseases of hepatocellular, testicular nonseminomatous origin, and occasionally of other entodermal origin. AFP measurement is widely accepted as a tumor marker and for monitoring the therapeutic effectiveness of hepatocellular cancer and nonseminomatous testicular cancer [21]. Herein, we designed a new electrochemical immunosensor for sensitive detection of AFP using graphene and nanogold-functionalized immunosensing interface.…”

Electrochemical Detecting Lung Cancer-Associated Antigen Based on Graphene-Gold Nanocomposite

“…However, complicated instrumentation and sophisticated and time-consuming pretreatment of sample are generally necessary in these methods. Consequently, electrochemical immunosensors have become a promising analytical method to detect antibody and antigen in the past decades, because of their high sensitivity, relatively low-cost, and quick analysis time [ 21 , 22 , 23 ]. Recently, nanoparticle-based electrochemical immunosensors have attracted intensive attention with the development of nanotechnology, due to their special electrical, optical, catalytic, and thermal properties [ 24 , 25 , 26 ].…”