An effective electrochemical signal amplification strategy based on enzyme membrane modification and redox probe immobilization was proposed to construct an amperometric immunosensor.L-cysteine@ferrocene functionalized chitosan,which possessed not only efficient redox-activity but also excellent film-forming ability,was coated on the bare glass carbon electrode. Moreover,the thiol groups(SH)in the ferrocenyl compound were used for gold nanoparticles immobilization via the strong bonding interaction,which could further be utilized for the immobilization of antibody biomolecules with well-retained bioactivities.Finally,glucose oxidase(GOD)as the enzyme membrane was employed to block the possible remaining active sites and avoid the nonspecific adsorption.With the excellent electrocatalytic properties of GOD towards glucose,the amplification of antigen-antibody interaction and the enhanced sensitivity could be achieved.Under the optimal conditions,the linear range of the proposed immunosensor for the determination of carcinoembryonic antigen(CEA)was from 0.05 to 100 ng/mL with a detection limit of 0.02 ng/mL(S/N=3).Moreover,the immunosensor exhibited good selectivity,stability and reproducibility, which provided a promising potential for clinical immunoassay.
A novel hydrogen peroxide(H2O2)biosensor was prepared.First,zirconium dioxide(ZrO2)were solubilized in the aqueous solution of a biopolymer chitosan(CS)and the mutlicarbon nanotubes(MWNTs)was introduced into the ZrO2-CS solution to get a ZrO2-CS-MWNTs composite.Then the ZrO2-CS-MWNTs composite was immobilized onto the surface of the glass carbon electrode(GCE).Subquently,a stable nano-Au film was electrodeposited on the ZrO2-CS-MWNTs modified electrode at a constant potential.Finally,horseradish peroxidase(HRP)was immobilized onto the nano-Au layer to obtain the HRP/nano-Au/ ZrO2-CS-MWNTs /GCE electrode.The results showed that the biosensor exhibited well reduction ability for hydrogen peroxide with high sensitivity and fastresponse time resulting from.The biosensor displayed a rapid response to H2O2 and the linear range of the biosensor was from 7.80×10-6 to 9.26×10-3 mol/L with the detection limit of 2.8×10-6 mol/L(S/N=3).In addition,the biosensor showed fast response,high sensitivity,good stability and reproducibility.
