Application Of Carbon Nitride Luminophore In Electrochemiluminescence Analysis

Graphite-phase polymeric carbon nitride(CN)is an emerging organic semiconductor,and the applications based on its electrochemiluminescent(ECL)properties in the field of sensing has drawn many attentions such as detecting cancer markers in recent years.As a rapidly growing number of human diseases are associated with abnormal DNA methylation,developing a sensitive MTase activity assay is of paramount significance in early disease diagnosis and therapy.Traditional detection methods including high performance liquid chromatography,gel electrophoresis,and radioactive labeling are golden standards,but they are laborious,time-intensive,and discontinuous and usually require expensive instruments.For this reason,various nanomaterial-derived biosensors using spectroscopic and electrochemical methods are proposed for detecting DNA MTase.In this thesis,we report a sandwich-assembled ECL biosensor using multifunctional CNNS to evaluate the Dam MTase activity.The CNNS could not only be used as an excellent substrate to conjugate a large amount of hairpin probe DNA to improve the sensitivity but also be utilized as an internal reliability checker and an analyte reporter in the bottom and top layers of the biosensor,respectively.Such a unique sandwich configuration of CNNS well coupled the advantages of ECL luminophor that were generally assembled in the bottom or top layer in a conventional manner.In another work,the change of the fluorescence intensity caused by the change of the distance between CNNS and dye is also investigated to offer a simple and easy analytical method for the detection of telomerase.The detailed works are summarized as follows:1.We constructed a self-detectable strategy for assembling multifunctional carbon nitride nanosheet sandwich structures with high sensitivity to detect DNA methylase activity by ECL.It was found that the ECL intensity increased with the increase of the Dam MTase concentration in the range of 0.05-80U/ml and the detection limit(LOD,S/N=3)was estimated to be 0.043U/ml.2.The changes of fluorescence signals were observed for CNNS in the presence of dyes with different concentration.Telomerase can change DNA into long-chain DNA and the length of DNA chain can control the distance between the CNNS and the dye,which made the changes of fluorescence intensity correlated to the activity of telomerase.This study provides a new perspective on the early prevention and diagnosis of deceases and provides a new successful examples of applying CNNS in the field of biosensors as a new type of material.