Study On The Construction Of Electrochemilummescence Immunosensor Based On Metal Nanoparticles And Metallic Oxide Nanoparticles

Electrochemiluminescence (ECL) innunosensor is a sensitive device which is developed to detect cancer biomarkers by combining ECL analtical method and immunoassay technology. It has many advantages, such as simple operation, rapid detection, high sensitivity and good selectivity.Due to the large specific surface area, high surface energy and the specific electroic structure and activity of surface atoms of metal nanoparticles and metallic oxide nanoparticles, it has excellent catalytic performance on many ECL reactions. Moreover, these nanoparticles also have good biocompatibility, so they can be used as biomarkers to enhance the ECL singals which can greatly improve the detection sensitivity.Therefore, we hope that metal nanoparticles and metallic nanoparticles are used to construct ECL immunosensor which has satisfactory sensitivity, selectivity and detection limit and can be used to detect cancer biomarkers. In our paper, research work is carried out from the aspects as follows:Part1Study on highly enhanced luminol ECL innunosensor based on L-Cysteine Film adsorbed by Au nanoparticlesIn this work, a novel label free ECL immunosensor based on the ECL of luminol for detection of a-1-fetoprotein (AFP) has been developed. For this proposed immunosensor, gold nanoparticles (AuNPs) were firstly electrodeposited on the glass carbon electrode (GCE) surface, which promoted the electron transfer and largely enhanced the ECL signal of luminol. Subsequently, L-cysteine self-assembled monolayer (SAM) was formed on the nano-Au modified electrode to further enhance the ECL signal and improve the absorption capacity of antibody. Then, EDC/NHS was used to activate the reaction between the-COOH/-NH2of L-cysteine and the NH2/-COOH of anti-AFP. At last bovine serum albumin (BSA) was used to block the nonspecific binding sites. As a result, the ECL of luminol enhanced by L-cysteine film was firstly developed for ultrasensitive immunosensor. Due to the enhancement of AuNPs and L-cysteine for the ECL of luminol, the properties of this immunosensor was largely improved. The developed immunosensor performed high sensitivity and wide linear range for detection of AFP in the linear range of0.001-20ng/mL, with a low detection limit of0.33pg/mL (defined as S/N=3). Moreover, the immunosensor showed good fabrication and detection reproducibility.Part2Study on highly sensitive luminol ECL immunosensor based on ZnO nanoparricles and glucose oxidase decorated grapheneIn this work, we reported a sandwiched luminol ECL immunosensor using ZnO nanoparticles (ZnONPs) and glucose oxidase (GOD) decorated graphene as labels and in situ generated hydrogen peroxide as coreactant. In order to construct the base of the immunosensor, a hybrid architecture of Au nanoparticles and graphene by reduction of HAuCl4and graphene oxide (GO) with ascorbic acid was prepared. The resulted hybrid architecture modified electrode provided an excellent platform for immobilization of antibody with good bioactivity and stability. Then, ZnONPs and GOD functionalized graphene labeled secondary antibody was designed for fabricating a novel sandwiched ECL immunosensor. Enhanced sensitivity was obtained by in situ generating hydrogen peroxide with glucose oxidase and the catalysis of ZnONPs to the ECL reaction of luminol-H2O2system. The as-prepared ECL immunosensor exhibited excellent analytical property for the detection of carcinoembryonic antigen (CEA) in the range from10pg/mL to80ng/mL and with a detection limit of3.3pg/mL (S/N=3). The amplification strategy performed good promise for clinical application of screening of cancer biomarkers.Part3Study on ultrasensitive luminol electrochemiluminescence immunosensor base on gold-coated Fe3O4nanoparticles and glucose oxidase modified L-Cysteine functionalized grapheneThis paper describes a novel enzyme and mimic enzyme amplification strategy for ultrasensitive electrochemiluminescence immunosensing. This approach utilizes gold-coated Fe3O4nanoparticles (Au@Fe3O4NPs) and GOD modified L-Cysteine functionalized graphene as labels to fabricate a sandwiched luminol electrochemiluminescence immunosensor for the sensitive determination of AFP. The results exhibited the aboved-mentioned nanocomposite labeled secondary antibody could highly improved the detection properties of the immunosensor. Under the optimal conditions, the proposed immunosensor could detect AFP in the range from0.1pg/mL to200ng/mL and with a detection limit of33fg/mL (S/N=3). A good mean apparent recovery in the range of85.2-102.0%was obtained over the entire linear dynamic range of the sensor response in the serum samples. Thus, the proposed method was proven to be a feasible quantitative method for immunoassay, which may open a new door for ultrasensitive detection of tumor markers in the serum of cancer patients.