A Prostate Specific Antigen Immunosensor Based on Biotinylated‐Antibody/Cyclodextrin Inclusion Complex: Fabrication and Electrochemical Studies

Abstract

Immobilization of biomolecules with a proper orientation is considered as a basis for diverse biotechnological applications. Herein, we report a host‐guest inclusion complexation between β‐cyclodextrin (β‐CD) and biotin as a versatile approach for the immobilization of biomolecules. As a practical application, a sandwich‐type electrochemical immunosensor was designed for the determination of prostate specific antigen (PSA). The immunosensor was fabricated by in situ electropolymerization of poly(N‐acetylaniline) onto a rGO‐modified Pt electrode. Then, β‐CD was covalently grafted onto the over‐oxidized polymer backbone. For improving the efficiency of the assay, AuNPs were casted on the polymeric film, on the surface of which thionine (TH) as an electron mediator was covalently immobilized. Using a host‐guest inclusion complexation between β‐CD and biotin, a β‐CD/biotin‐Ab1/PSA/Ab2‐horseradish peroxidase (HRP) sandwich was formed on the electrode surface. The analytical signal was produced via electrochemical reduction of THox, generated by biocatalytic oxidation of the THred in the presence of HRP/H2O2. Under optimal conditions, the proposed sensor responded linearly to PSA in the range from 10.0 pg mL−1 to 25.0 ng mL−1, with a low detection limit of 6.7 pg mL−1 (S/N=3). Kinetic parameters of the interaction of β‐CD with Ab1 were also investigated. Finally, the applicability of the immunosensor was successfully investigated for the detection of PSA in human serum samples.

Smartphone-Based Electrochemiluminescence for Visual Simultaneous Detection of RASSF1A and SLC5A8 Tumor Suppressor Gene Methylation in Thyroid Cancer Patient Plasma

“…The affinities of the capture DNA probes (probe R and probe S) toward relative target DNA were determined using electrochemical impedance spectroscopy (EIS) in different concentrations of target DNA in a 2.5 mM Fe­(CN) 6 3–/4– solution containing 0.1 M KCl , (details of the measurement are given in the Supporting Information, Section S20). According to the Hill plot as a function of log­[ target ssDNA ], the obtained K d from the intercepts for RASSF1A (Figure S-13A) and SLC5A8 (Figure S-13B) targets were 2.04 and 2.7 ng –1 , respectively.…”

Thin Films and Composites Based on Graphene for Electrochemical Detection of Biologically‐relevant Molecules

“…They have been explored in detecting proteins and small molecules linked to diseases, including cancer . Immobilization of antibodies on the device with an appropriate orientation and with small non‐specific adsorption are crucial for effective biosensing performance (e. g. long‐term stability, short responde times, precision and high sensitivity) . Promising antibody immobilization strategies have been implemented, which include covalent binding, entrapment, encapsulation, adsorption, cross‐linking within a highly crosslinked polymer matrix, and affinity approaches .…”

“…It is significant that early detection normally increases the chances of cure, which motivates the search for low cost detection methods such as those involving electrochemical biosensors. The literature is rich in examples of electrochemical biosensors to detect cancer biomarkers , some of which made use of graphene as discussed below.…”

An electrochemical sensing platform for sensitive detection DNA methylation using Fe3O4/TMC/Au nanocomposite and poly(l-arginine)/reduced graphene oxide modified screen-printed carbon electrode

“…First, 5 μL of 1 mg ml −1 GO in water was drop-casted onto the working electrode and a thin film of RGO was formed by CV method from −1.5 to 0 V vs. Ag/AgCl for 10 cycles at a scan rate of 100 mV s −1 . 22,30 The modified electrode was then washed with PBS solution to remove remaining GO particles on the electrode surface.…”