| Luminol,as a classic emitter in the field of electrochemiluminescence（ECL）,could produce strong ECL signal in alkaline solution when hydrogen peroxide（H2O2）was used as coreactant.Dissolved oxygen（O2）had better biological activity and renewability than H2O2 as an endogenous coreactant.However,due to the low ECL reactivity of dissolved O2,there were still several urgent problems to be solved in the bioanalysis using luminol as the emitters and dissolved O2 as the coreactant in the ECL system:（1）How to propose a highly efficient and easily available coreaction accelerator to accelerate the dissolving O2 reactivity for enhancing the ECL signal of luminol;（2）How to explore a new type of emitter with high ECL luminous efficiency and improve the accuracy and specificity of ECL system in biological analysis;（3）How to design an efficient target recognition strategy to achieve high sensitivity detection of different types of target.A novel ECL system based on luminol was constructed.The specific research work is divided into the following parts:（1）Intense electrochemiluminescence from anorganic microcrystal accelerated H2O2-free luminol system for micro RNA detection.Dissolved O2 had the advantages of better stability and non toxicity as an endogenous coreactant.However,the reaction activity of dissolved oxygen（O2）was often very low,which limited the application of luminol/dissolved O2 binary ECL system extently.9,10-diphenylanthracene（DPA）was often used as ECL emitters due to their high fluorescence quantum yields and good ECL properties.However,the properties of adsorption and catalytic gas of PAHs organic nanocrystals was rarely mentioned and applied in the field of ECL.A kind of organic microcrystal,9,10-diphenylanthracene microcrys-tals（DPA MCs）,was developed as a novel coreactant accelerator to efficiently catalyze dissolved O2 for more reactive oxygen species（ROSs）generation,achieving intense ECL for a H2O2-free luminol system.Moreover,based on this ternary ECL system,a ECL biosensor for micro RNA-21（mi RNA-21）detection was constructed combining a sensitive target recycling amplification strategy and an enzyme-mediated recycling strand displacement reaction（RSDR）,which showed wide linear range from 100 amol/L～100pmol/L,and the limit of detection of 18.3 amol/L.（2）N,S co-doped carbon dots based on luminol as a new electrochemiluminescence material and its application in dopamine detection.Carbon dots（CDs）have attracted great interest of researchers due to their excellent photostability,small size,low toxicity,good biocompatibility and inert chemical properties.However,the synthesis controllability of the size and morphology of CDs was poor,so the luminescence mechanism of CDs was difficult to be accurately explained.In this work,a new idea of pre-introduction of luminescence center was proposed,which introduced a large number of known luminescence center on the surface of CDs and around carbon core to make them have specific luminescence center and efficient ECL signal response.A kind of N,S co-doped CDs（N,S CDs）had synthesized through one pot hydrothermal method between luminol and dithiosalicylic acid（DTSA）in this work.The hydrazide groups in the luminol as the predictable luminescence center was introduced into the N,S CDs.By the introducing large number of hydrazide groups in the N,S CDs,the ECL intensity of CDs could be significantly improved in the PBS without any exogenous coreactant.With the aid of the excellent performance,the N,S CDs was used to be an advanced ECL emitters to fabricated a ECL biosensor for dopamine（DA）detection,which showed excellent linear range from 1 nmol/L～100μmol/L with detection limit of 0.16 nmol/L.（3）An“off-on”biosensor based on N,S CDs and its application in MUC1 detection.Signal“on”and signal“off”were two common modes used in ECL biosensor construction.The“on”and“off”of the signal realize the conversion of the detection signal so as to realize the sensitive detection of the target.To construct a simplex“signal-off”ECL biosensor with excellent performance,not only should the original luminescence signal of the emitter be strong enough but also quenching efficiency of quencher should be high enough.In this work,we constructed a signal“off-on”ECL biosensor to detect MUC1 based on the quenching effect of Fc on N,S CDs.At the same time,the repeated high efficient cleave of T7 exonuclease（T7 Exo）on the solution and electrode surface,realizing the sensitive detection of MUC1.The constructed biosensor had a good linear response in the range of 1 fg/m L～1 ng/m L,and the detection limit was0.39 fg/mL. |
