Fabrication Of Electrochemical Immunosensor Research Articles

Bovine Serum Albumin-Dependent Charge-Transfer Kinetics Controls the Electrochemical Immunosensitive Detection: Vibrio cholerae as a Model Bioanalyte.

This work investigates how bovine serum albumin (BSA), a commonly used protein in the fabrication of electrochemical immunosensors, can impact on the sensitivity of detection when integrated with antibody (Ab) pre-encapsulated with (i) insulating polyacrylonitrile (PAN) fibre (i.e., GCE-PAN-Ab-BSA immunosensor) or (ii) conducting PAN-grafted iron (II) phthalocyanine (FePc) (i.e., GCE-PAN@FePc-Ab-BSA immunosensor), using Vibrio cholerae toxin as a case study bioanalyte. Both immunosensors show different charge-transfer kinetics that strongly impact on their immunosensitive detection. From the electrochemical data, GCE-PAN-Ab-BSA is more insulating with the presence of BSA, while the GCE-PAN@FePc-Ab-BSA is more conducting with BSA. The CV of the GCE-PAN-Ab-BSA is dominated by radial diffusion process, while that of the GCE-PAN@FePc-Ab-BSA is planar diffusion process. The behaviour of GCE-PAN@FePc-Ab-BSA has been associated with the facile coordination of BSA and FePc that permits co-operative charge-transport of the redox probe, while that of the GCE-PAN-Ab-BSA is related to the interaction-induced PAN-BSA insulating state that suppresses charge-transport. As a consequence of these different interaction processes, GCE-PAN-Ab-BSA immunosensor provides higher electroanalytical performance for the detection of Vibrio cholerae toxin (with sensitivity of 16.12 Ω/log [VCT, g/mL] and limit of detection (LoD) of 3.20 × 10−13 g/mL compared to those of the GCE-PAN@FePc-Ab-BSA (4.16 Ω/log (VCT, g mL−1) and 2.00 × 10−12 g/mL). The study confirms the need for a thorough understanding of the physico-chemistries of the electrode platforms for the construction of immunosensors. Although this work is on immunosensors for cholera infection, it may well apply to other immunosensors.Graphical

An efficient label-free immunosensor based on ce-MoS2/AgNR composites and screen-printed electrodes for PSA detection

Label-free electrochemical immunosensors (EIs) are simple and sensitive in cancer diagnosis. Electrode materials which can offer a large specific area and excellent electrical conductivity play a critical role in the fabrication of EIs. In our study, ce-MoS2/AgNR composite was synthesized via Van der Waals force and electrostatic interaction between chemical exfoliated MoS2 nanosheets (ce-MoS2) and Ag nanorods (AgNRs). The conductivity of ce-MoS2/AgNR composite was almost three times higher than single ce-MoS2 because of the synergistic effect between ce-MoS2 and AgNRs. Furthermore, AgNRs could effectively inhibit the stacking of MoS2 nanosheets. The EIs for prostate-specific antigen (PSA) detection were fabricated based on ce-MoS2/AgNR composite. The fabricated EIs retained a wide linear response range (0.1–1000 ng/ml), low sensitivity (0.019 μA/(ng ml−1)), and low detection limit (0.051 ng/ml) for the detection of PSA. Therefore, the EIs based on screen-printed electrode (SPE) and ce-MoS2/AgNR composite could be applied to clinical diagnosis of prostatic cancer and have potential application in the detection of other cancer biomarkers.

Fabrication of Electrochemical Immunosensor Using Gold Nanoclusters as Signal Amplification Labels

A cheap and portable electrochemical immunosensor based on silver-enhanced colloidal gold electrochemical stripping technique and gold nanoclusters(AuNCs) labels was proposed for the detection of human IgG.Inspired by the adhesive proteins that secreted by marine mussels,the stable and robust film-poly(dopamine) was used to immobilize biomolecules(Ab1) on an indium tin oxide(ITO) electrode for the fabrication of immunosensor.Then,human IgG and AuNCs-Ab2 were successively immobilized to the Ab1 modified ITO electrode.The process for the fabrication of sandwich immunosensor was monitored by electrochemical impedance spectroscopy.Through the immunoreaction between antigen and antibody,IgG could be quantitatively determined by anodic stripping voltammetry.On the basis of the dual signal amplification of AuNCs labels and silver enhancement technique,the sensitivity was improved to 0.5 ng/L.Moreover,the proposed immunosensor could be used in clinical diagnosis.