The Study And Application Of Novel Strategies For Luminol Eletrochemiluminesence Signal Amplification

Luminol-based ECL provides many valuable advantages,such as,luminol ECL can be used specially in aqueous medium with sufficient reagent source and high luminous efficiency.Therefore,the luminol-based ECL has been widely researched and applied in many fields.However,for a long time,the ECL intensity of luminol was really weak under neutral condition,which limits its application in some neutral systems（eg,the detection of biologically active substances）.In order to solve this problem,how to better enhance the ECL intensity of luminol in the neutral system has always been a hot topic in the ECL research field.At present,modifying the working electrode and changing the solution medium are the generally accepted two approaches to sensitize the luminol-based ECL.However,the methods of electrode modification are generally complicated and time-consuming,and the change of solution medium usually requires the addition of many foreign substances.In view of the above problems,there are two novel methods developed for the sensitization of luminol-based ECL in this paper.The sensitization mechanism of these methods were discussed in detail and applied to the detection of H₂O₂.The main research contents are as follows:（1）A simple and time-saving strategy was developed for the amplification of electrochemiluminescence（ECL）by dropping the noncoplanar tetraphenylethylene（TPE）solution on the surface of gold electrode.The selfassembled TPE aggregates exhibited inherent porous structures,endowing them with high specific surface area and oxygen adsorption capability.Therefore,the fabricated porous structures could lead to a 50-fold increase in the ECL signal of luminol in neutral aqueous solution,in comparison to that on the bare electrode.In contrast,the aggregates of the two typical coplanar polycyclic aromatic hydrocarbons（PAHs）,perylene and pyrene,gave a weaker ECL enhancement,owing to their disc-like molecular structure and densely packed layers.under aggregated conditions.The proposed ECL system has been successfully applied for the detection of hydrogen peroxide（H₂O₂）in the linear range of 0.25～1000 μM with a detection limit（S/N = 3）of 0.1μM.Our findings provide inspiration for revealing the role of inherent molecular structure in the aggregate configuration,and they provide attractive perspectives for the usage of noncoplanar molecules in analytical applications.（2）The effective sensitization effect of formamide on luminol-based ECL under neutral condition was discovered for the first time,which was based on the introduction of slight formamide into the electrolyte.Meanwhile,the ECL signal sensitized by formamide possessed good reproducibility and stability.In addition,the sensitization mechanism was further researched.The medium of luminol solution would be changed by formamide,which could solubilize luminol in neutral medium.Meanwhile,the deprotonation of luminol could be catalyzed to promote the electrochemical oxidation of luminol through molecular hydrogen bonding interaction between formamide and luminol,resulting in the enhancement of ECL intensity.On basis of this exciting phenomenon,we not only found a novel sensitizer to enhance the ECL intensity of luminol in neutral medium,and provided a theoretical basis for further researching the mechanism of luminol-based ECL,but also provided the opportunity to broaden the application area of luminol-based ECL.