Nanomaterials Based Signal Amplification Strategy For Electrochemiluminescence Biosensors

By the advantages of electrochemiluminescence?ECL?technology,such as high sensitivity,high controllability,and rapidity,it has become hot spot in the field of analytical chemistry in recent years.However,in the absence of coreaction reagent or other signal amplification methods,the response signal of the ECL sensor is often weak.Therefore,building the signal amplification technique to amplify the response signal of the ECL sensor has become the key to the further development of this technology.According to many reports,the signal amplification and sensitivity of ECL sensors can be effectively improved by constructing new signal amplification strategies based on nanomaterials.This work mainly designed and synthesized new luminescent materials,new nano-immobilized platforms,and nanomaterials based novel nano-signal enhancers,and developed a variety of signal amplification strategies and applied them to different types of biosensor construction processes.This studied thesis is mainly divided in the following sections:1,In situ electro-polymerization of nitrogen doped carbon dots and their application in an electrochemiluminescence biosensor for the detection of intracellular lead ions.In this paper,a novel sensitive electrochemiluminescence?ECL?biosensors was developed for the detection of intracellular lead ions(Pb²⁺)using N-doped carbon dots?N-CD?in-situ electropolymerized on glassy carbon electrode?GCE?as emitters and Pd-Au hexahedrons?Pd@AuHOHs?as enhancers.First,o-phenylenediamine?OPD?is electropolymerized on GCE to form N-CD which contained amino groups.Then,Ag nanoparticles?AgNPs?,which possessed excellent conductivity and biocompatibility,were modified on the N-CD through Ag-N bonds to immobilize the capture DNA?T1?.Subsequently,complementary DNA?T2?and ssDNA1?S1?labeled Pd@AuHOHs?Pd@AuHOHs-T2-S1?were introduced on the electrode through the hybridization between T1 and T2.At the same time,the ssDNA2?S2?-labeled Pd@AuHOHs?Pd@AuHOHs-S2?was introduced through the hybridization of S1 and S2,forming a Pd@AuHOHs-DNA dendrimer structure on the surface of the electrode.It is noteworthy that Pd@AuHOHs had a specific catalytic activity for ECL reactions and efficiently enhanced the ECL signal of N-CDs.Through rational design,a large number of S1 and S2 DNA sequences were coupled to intracellular Pb²⁺,resulting in Pb²⁺stable G-quadruplex?G4?structures and quenching the ECL intensity of N-CDs.In addition,the sensor has great potential for studying the biological behavior of heavy metal ions in other cells.2,A novel solid-state Ru?bpy?₃²⁺electrochemiluminescence immunosensor based on poly?ethylenimine?and polyamidoamine dendrimers as co-reactants.In this study,a novel solid-state tris?2,2-bipyridyl?ruthenium?II?electrochemiluminescence?ECL?immunosensor was constructed based on polyethyleneimine functionalized graphene oxide?PEI-RGO?and gold nanoparticles?AuNPs?modified polyamide?PAMAM?for sensitive detection of alpha-fetoprotein?AFP?.Both PEI and PAMAM are polymers with a large number of amino groups,which can as co-reactants to greatly increase the ECL signal of tris?2,2-bipyridyl?ruthenium?II?.In order to improve the low conductivity of PAMAM,the AuNPs were modified on the PAMAM via Au-N bond,and the prepared AuNPs-PAMAM was modified on PEI-RGO.Then,the detection antibody?Ab2?was further labeled on the AuNPs-PAMAM/PEI-rGO nanomaterial and introduced into the surface of GCE by a sandwich immunoreaction.On the other hand,the complexes of nafion and platinum nanoparticles?Ru-PtNPs?were mixed with ruthenium complexes to prepare ECL substrates and modified on the surface of the GCE,reducing the consumption of ruthenium complexes and improving the luminous efficiency.As a result,the prooposed ECL immunosensor showed a good response to AFP.The linear range is 0.01 pg mL^-1 to 10 ng mL^-1 with a detection limit of 3.3 fg mL^-1.At the same time,the obtained ECL immunosensor has good stability,selectivity and reproducibility,which made it have good potential for clinical detection.3,Luminescence-functionalized metal–organic frameworks based on a Ruthenium?II?complex:a signal amplification strategy for electrogenerated chemiluminescence immunosensors.In this study,a novel luminescence functional metal organic frameworks?MOFs?with excellent electroluminescent properties was synthesized using zinc ion as the central ion and[Ru?dcbpy?₃]²⁺as the ligand.The synthesized luminescent functionalized MOFs were used to construct a luminescence signal“signal on”electrochemiluminescence immunosensor that was used to detect N-terminal pro-brain natriuretic peptide?NT-proBNP?.Consistent with the prediction,this article obtained a strong electrochemiluminescence signal through a simple preparation strategy,which not only because the luminescent functionalized MOF increased the loading capacity of[Ru?dcbpy?₃]²⁺,but also because MOF served as a loading platform in electrochemiluminescence immunosensors.In addition,the proposed electrochemiluminescence immunosensor exhibited excellent sensitivity with a wide linear range of 5pg ml^-11 to 25 ng mL^-1 and a detection limit of 1.67 pg mL^-1.The results show that the luminescent functionalized MOFs provide a novel amplification strategy for the construction of electrochemiluminescence immunosensors,which has broad application prospects in biological analysis.4,Ultrasensitive assay for telomerase activity via self-enhanced electrochemiluminescent Ruthenium complex doped metal-organic frameworks with high emission efficiency.In this study,a novel"off-on"type of ultrasensitive electrochemiluminescence?ECL?biosensor was developed based on the self-enhanced polyethylene imine?Ru-PEI?ruthenium doped zeolite with imidazole skeleton-8?Ru-PEI@ZIF-8?and enzymatic cycling amplification strategy for the detection of telomerase activity.Ru-PEI@ZIF-8 nanocomposite is synthesized by adding self-enhanced Ru-PEI complex during the growth of zeolite imidazole framework-8?ZIF-8?.A high ECL efficiency and excellent stability was obtained.In addition,self-enhanced Ru-PEI complexes in the outer layer and inner layer of Ru-PEI@ZIF-8 self-enhanced Ru-PEI@ZIF-8 can be excited by electrons due to the good porosity of Ru-PEI@ZIF-8,resulting in a significant increased ECL signal.In order to improve the sensitivity of the proposed biosensor furthermore,the telomerase activity was converted to trigger DNA,which was amplified by enzyme assisted DNA amplification strategy.The proposed ECL biosensor showed excellent performances in the detection of telomerase activity from 5 x 10¹ to 10⁶Hela cells,with a detection limit of 11 cells.In addition,this method is applied to detect telomerase activity in cancer cells treated with anti-cancer drugs,indicating the potential application of the proposed biosensor as an evaluation tool for anti-cancer drug screening.