Perylene Diimide As Luminophores For Ultrasensitive Electrochemiluminescence Immunosensor

The sensitivity and selectivity of electrochemiluminescence（ECL）immunosensor are affected by many factors,such as external environment and instrument,excitation potential,emission wavelength,dispersion of luminophores and loading amount of luminophores on the carrier.Ratiometric immunosensor could eliminate the interference from the external environment and instrument through the self-calibration of two ECL signals.The luminophores with low excitation potential and long emission wavelength can not only eliminate the background interference but also protect the activity of biomolecules.Lowly aggregated luminophores could be used to prepare highly productive ECL nanomaterials.Nanocarrier with large specific surface area can enhance the electrochemiluminescence signal by increasing loading amount of luminophores.Perylene diimide derivatives could produce strong near-infrared（IR）ECL at low potential and have drawn widespread attention.This thesis uses the perylene diimide derivative as luminophores to construct a sensitive electrochemical luminescence immunosensor from the following three aspects.1.Carbon Nitride and N,N-Dimethyl-3,4,9,10-perylenedicarboximide were used as luminophores for a Dual-potential Ratiometric ImmunosensorWe used carbon nitride nanosheets（CNNS）and perylene diimide（PDI-CH₃）as ECL donor/acceptor pair to fabricate dual-potential ratiometric immunosensor to detect tumor marker.Carbon nitride nanosheets could emit ECL at-1.2 V with wavelength 495 nm.Perylene diimide could absorb the emission at 495 nm and also emit ECL at-0.47 V with wavelength 689 nm.Moreover,gold nanoparticles（Au NPs）was grafted on carbon nitride nanosheets as ECL platform to immobilize primary antibody（Ab₁）.Perylene diimide was grafted on graphene oxide（GO）as ECL materials to label secondary antibody（Ab₂）.Finally,CEA as target protein model and Ab₂labeled ECL materials were stepwisely immobilized on ECL platform to fabricate immunosensor.The ratio of ECL intensities from CNNS and PDI-CH₃was taken as detection signal.The results show that the sensor has high sensitivity and good linear relationship to CEA in the range of 0 to-1.2 V cyclic scanning voltage,and the sensor has a satisfactory recovery rate in the detection of actual samples,which proves the practical application value of this strategy.2.Lowly-Aggregated N,N-dicaproate sodium-3,4,9,10-perylenedicarboximide as Near-Infrared Electrochemiluminescence luminophore for Ultrasensitive Immunosensor at Low PotentialAt present,due to the strong hydrophobicity of the framework of perylene diimide andπ-πconjugation,the reported perylene diimide derivatives always aggregated into micro-rods and accumulated into large blocks,which largely influenced their application in biological field such as bio-sensing and bio-imaging.To overcome this obstacle,we designed a novel perylene diimide molecule N,N-dicaproate sodium-3,4,9,10-perylenedicarboximide（PDI-COONa）.Furthermore,an ultrasensitive sandwiched immunosensor was fabricated using this ECL nanomaterial for detecting alpha-fetoprotein（AFP）between 0 to-0.6 V.The results showed that the sensor has high sensitivity and good linearity in the range of linear scanning voltage from 0 to-0.6 V,and the sensor has a satisfactory recovery rate in actual sample detection,which proves that it has potential application value in clinical detection.3.Study on the Enhancement of Electrochemiluminescence Signal by using MOF PCN-777 as NanocarrierWe synthesized a porous MOF material,PCN-777,and used PCN-777 as a nano-carrier to enhance the electrochemical luminescence signal of the material by improving loading amount of PDI-COONa.We studied the nano-composite PCN-777/PDI-COO^-electrochemiluminescence measurements showed that PCN-777 as a carrier did not enhance the electrochemical luminescence intensity of the material.The previously reported perylene diimide derivatives were all supported on GO,and the mechanism proved that the low potential luminescence was caused by the dimer,and GO was favorable for the formation of the dimer.Therefore,the carrier PCN-777 we selected failed to enhance the luminescence intensity of the material.The reason should be that PDI-COO^-existed in the form of monomer in PCN-777/PDI-COO^-,and the carrier PCN-777 was not favorable for the formation of dimer,so the electrochemiluminescence signal could not be improved.