Electrochemiluminescence Sensors Based On Graphene Quantum Dots And Poly(5-Formylindole)/Graphene Nanocomposites

Conducting polymers?CPs?are functional polymer materials with high conductivity which contain ? bond in molecule.When the monomor was modified with aldehyde groups and carboxyl functional groups,the performance showed a larger improvement than polyindole.Graphene oxide?GO?is water-solutable nano-material,it can be reduced to graphene?erGO?in electrochemical reduction way.Then electrochemical polymerization was reacted between erGO and 5-formylindole?5FIn?monomer through ?-? action.A novel poly?5-formylindole?/erGO?P5FIn/erGO?nanocomposite was prepared,which imoroved the performance of biocompatibility.Graphene quantum dots?GQDs?is a novel nano carbon material,it has shown great promise for the applications in biosensor by the unusual properties such as low toxicity,attractive biocompatibility and unique electro-optical properties.Electrochemiluminescence?ECL?sensors based on P5FIn/erGO nanocomposite and GQDs were fabricated in this work.The major contents of the thesis are as followes:1.A novel P5FIn/erGO nanocomposite was prepared by electrochemical polymerization of 5FIn monomer in acetonitrile on erGO modified electrode.As revealed by the results of cyclic voltammetry studies,P5FIn/erGO nanocomposite showed higher redox active,higher electrochemical activity,larger peak current and wider electrochemical window than P5 FIn.Scanning electron microscope?SEM?showed that P5 FIn film was loosely packed porous structure in the form of net-like morphology.P5FIn/erGO nanocomposite has a nanosheet structure that is homogeneous,uniform and compact.The nanostructure was benefit for electron transportation.The ECL property studies of GQDs showed that the as-prepared GQDs had stable and high EC L intensity.The properties of GQDs and P5FIn/erGO nanocomposite have broad application prospects in biosensors research.2.A sandwich-type ECL immunosensor based on P5FIn/erGO nanocomposite and GQDs was fabricated for carcinoembryonic antigen?CEA?detection.P5FIn/erGO nanocomposite not only used for the immobilization of primary antibody?Ab1?,but also improved the conductivity of the electrode.Gold nanoparticle?AuNP?was modified on the surface of GQDs,and the redulted GQDs@AuNP was used as EC L signal probe after co mbined with sectondary antibody?Ab2?.The linear range of this sensor was from 0.1 p g mL-1-10 ng mL-1,the detection limit was calculated as 3.78 fg mL-1.The large surface area of the nanometer-sized GQDs and integration of P5FIn/erGO provided great active sites for the C EA,leading to a low detection limit.The ECL immunosensor performed with admirable stability and good selectivity and reproducibility as well,it provides a high sensitivity,high selectivity analytical technique for the determination of CEA in real samples.3.A simple and ultrasensitive ECL sensor for the determination of mercuric ions was developed based on P5FIn/erGO nanocomposite and GQ Ds.In this work,DNA S1 and DNA S2 are thymine-enriched single-strand DNA,Amino modified DNA S1 can connect with P5FIn/erGO nanocomposite.When Hg²⁺ was added to the electrodes,the thymine-Hg²⁺-thymine(T-Hg²⁺-T)interaction between two ssDNA probes directed the coordination between the GQD-EC L nanoprobe complexes.GQDs-ECL nanoprobe was consisted of GQDs,Linker DNA S3,Au NP and DNA S2.The detection range of the sensor was from 1.5-90 nmol L-1,and the detection limit was 0.16 nmol L-1.This novel EC L biosensor showed good stability,excellent selectivity and high sensitivity over a series of interference metal ions.It can not only provides a high sensitivity and convenient way for Hg²⁺ detection,but also widens the application of GQDs in environmental monitoring.