Research And Application Of Novel Electrochemiluminescent Materials In Biosensors

Electrochemiluminescence?ECL?analysis technology,which combines the characteristics of electrochemical and chemiluminescence,has showing broad application prospects in the field of biological analysis due to its inherent advantages of simple equipment,fast response,good selectivity and high sensitivity.Traditional ECL materials?luminal and Ru complex?generally suffer from some shortcomings,such as complex preparation process,high cost and difficulty in loading.Therefore,it is particularly important to synthesize novel ECL materials with high luminescence efficiency and explore their ECL properties in analytical applications.In the current work,three kinds of novel ECL materials were synthesized,including tin dioxide nanoflowers,tetraphenylethylene microcrystals and perylene composite microcrystals doped with tetrakis?4-aminophenyl?ethene.And on the basis,combined with signal amplification strategy,several ECL biosensors were constructed for high sensitivity detection of biomolecules.The main research work of this paper includes the following aspects:1.Based on the silver nanoparticles functionalized SnO₂ nanoflowers as efficient signal probes for electrochemiluminescence biosensor constructionMetal oxide semiconductor nanocrystals?NCs?,which emerged as a novel class of electrochemiluminescence?ECL?emitters with low cost and good biocompatibility,have attracted particular research interests in ECL biosensors.However,their analytical applications still remained a substantial challenge of relatively low ECL intensity.Herein,the novel self-accelerated ECL emitters of silver nanoparticles functionalized SnO₂ nanoflowers?Ag@SnO₂ NFs?were first prepared by in situ generating silver nanoparticles on the surface of SnO₂ NFs via silver mirror reaction,which exhibited highintensity ECL emission with the maximum emission peak at 542 nm in the case of S₂O₈^2-as a co-reactant.It was worthy to note that compared with traditional ECL emitters of SnO₂ NCs with diameters below 10 nm,the obtained Ag@SnO₂ NFs with diameters about 1²?M showed a stronger ECL emission.The ECL enhancement was supposed to derive from?1?the strong size effect of flower-like nanostructure aggregating by ultrathin SnO₂ nanosheets,which would offer large amount of tin interstitials or oxygen vacancies.?2?the in situ generated silver nanoparticles?Ag NPs?as co-reaction accelerator,which would generate more oxidizing intermediate(SO₄^·-)to significantly self-promote the ECL emission of Ag@SnO₂ NFs.Given these attributes,we developed a sensitive ECL immunosensor for the detection of cardiac troponin T?cTnT?utilizing Ag@SnO₂ NFs as efficient signal probes,which showed outstanding sensitivity with a favorable linear range from 1 fg/mL to 100 pg/mL and relatively low detection limit of 0.11 fg/mL.2.Basedonthetetraphenylethylenemicrocrystalsasnovel electrochemiluminescence emitter for biosensor constructionIn this work,hexagonal tetraphenylethylene microcrystals?TPE MCs?were prepared for the first time.It was found that the TPE in aggregate state?TPE MCs?showed a significantly enhanced ECL response compared with TPE molecules in free state.Based on this magic phenomenon,a new mechanism named restriction of intramolecular motions-driven ECL?RIM-ECL?enhancement was first proposed.Inspired by the unique luminescence characteristic of TPE MCs,we integrated the novel ECL emitter of TPE MCs and target-activated bipedal DNA walker together to fabricate a sensitive“off-on”ECL biosensor for Mucin 1?MUC1?assay,which exhibited desirable linear response for a concentration scope from 1 fg/mL to 1 ng/mL with a low detection limit of 0.29 fg/mL.In addition,the RIM enhanced ECL demonstrated by the TPE MCs provides a new chapter in the exploration of aggregated organic emitters for further applications.3.Basedontheperylenecompositemicrocrystalsdopedwith tetrakis?4-aminophenyl?ethaneasnovelelectrochemiluminescenceemitter constructing biosensorPerylene and its derivatives,as classical organic polycyclic aromatic hydrocarbons?PAHs?ECL materials,have attracted extensive attention due to their excellent photoelectric activity and good structural controllability.As is well known,the molecular structure of perylene is composed of five coplanar aromatic rings.There are intense?-?stacking interactions between perylene molecules,which leads to its existence in the form of aggregates and poor solubility in aqueous media.Unfortunately,such aggregation could weaken or even quench their emission intensity owing to the aggregation-caused quenching?ACQ?effect,finally limitting the analytical application of organic luminophores in biological detection.In this work,the perylene composite microcrystals?ETTA@PeMCs?dopedwithnon-planarmolecular tetrakis?4-aminophenyl?ethene were synthesized in aqueous phase by the surfactant assisted self-assembly method.During the process,the intense?-?stacking interactions of perylene monomers were suppressed by doping.As a result,the ETTA@Pe MCs exhibited a significantly enhanced ECL signal compared to that of alone perylene microcrystals?Pe MCs?in the case of S₂O₈^2-as a co-reactant.Moreover,the ETTA@Pe MCs,as a novel ECL luminophore,was utilized to fabricate a sensitive ECL biosensor for the quantitative analysis of dopamine?DA?,which displayed favorable linear response from 1 nmol/L¹00?mol/L with detection limit of 0.96 nmol/L.