Renewable Protein A modified graphite-epoxy composite for electrochemical immunosensing.
A novel rigid and renewable transducing material for electrochemical immunosensing, based on Protein A bulk-modified graphite-epoxy biocomposite (ProtA-GEB) is reported. Protein A is able to bind to the Fc region of antibodies and provide an affinity matrix for antibody immobilisation onto the transducer. The rigid conducting biocomposite acts not only as a transducer, but also as a reservoir for protein A. After use, the electrode surface can be renewed by a simple polishing procedure, highlighting a clear advantage of this new approach with respect to classical immunoassays. The performance of ProtA-GEB transducers was compared with surface-modified transducers based on a simple dry adsorption procedure, where both Protein A and directly the antibody were adsorbed onto the surface of graphite-epoxy composite (ProtA/GEC and IgG/GEC, respectively). The application of the new biocomposite material in electrochemical immunosensing was studied using a model competitive immunoassay. The immunological reaction was detected using an enzymatic-labeling procedure together with the amperometric detection through a suitable substrate (H(2)O(2)) for the enzyme (HRP). The enzymatic labelling was performed using a two-step procedure based on the biotin/streptavidin interaction as well as a one-step procedure using an antibody labelled with the enzyme. Electrochemical and microscopic characterisation of ProtA-GEB transducer, optimisation of the immunosensor design as well as the stability of this material are also reported.
Zacco
E
E
Grup de Sensors i Biosensors, Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain.
Pividori
M I
MI
Llopis
X
X
Del Valle
M
M
Alegret
S
S
D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D004852:Epoxy Compounds; D006108:Graphite; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007074:Immunoglobulin G / Q000737:chemistry*; D018613:Microscopy, Confocal; D013205:Staphylococcal Protein A / Q000737:chemistry*; D014159:Transducers
D004852:Epoxy Compounds; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D006108:Graphite