The Preparation Of Electrochemiluminescence Sensor And Its Application Of Mycotoxin Detection

Electrochemiluminescence(ECL)is an analytical method which combines techniques of electrochemistry with chemiluminescence.In recent years,ECL has been intensively adopted in the fields of immunoassays,environmental monitoring and food security owing to its remarkable advantages such as high sensitivity,excellent controllability,wide linear range and so on.Nowadays,it has attracted great interest for science researchers to study the signal amplification strategies of ECL and combine ECL with other technologies.Mycotoxins are secondary metabolites of fungi,especially molds.Many mycotoxins are harmful to human beings and animals through diet.In this paper,we fabricated two different ECL sensors based on the ECL property of tris(2,2'-bipyridine)ruthenium(II)(Ru(bpy)32+)and CdTe quantum dots(QDs),which were used for the quantitative analysis and determination of fumonisin B1(FB1)and ochratoxin A(OTA)in food.The contents of this thesis mainly contain the following two parts:(1)A molecularly imprinted electrochemiluminescence(MIP-ECL)sensor was successfully fabricated using FB1 as the template molecule.Gold nanoparticles(AuNPs)could greatly enhanced the ECL signal of Ru@SiO2 due to the localized surface plasmon resonance(LSPR)and electrocatalysis effect.Ru@SiO2 NPs worked as the luminophor on the electrode and AuNPs facilitated the ECL emission.Meanwhile,the amino group of FB1 could act as the ECL coreactant of Ru@SiO2 NPs.When FB1 were eluted from the molecular imprinted film,ECL signal rapidly decreased for the lack of coreactant.After incubated in the FB1 solution,FB1 rebound to imprinted cavities again,resulting in a signal enhancement.Under the optimal experimental conditions,the sensor exhibited an excellent linear relationship between the ECL intensity change and the concentration of FB1 in the range of 0.001 to 100 ng·mL-1.Additionally,the limit of detection(LOD)was estimated as 0.35 pg·mL-1.All the results showed that the proposed sensor possessed desirable selectivity,stability and reproducibility.This ECL sensor could be applied to detect FB1 in maize samples with the recoveries range from 92.2%to 104.5%.(2)An electrochemiluminescent aptasensor based on the electrochemiluminescence resonance energy transfer(ECL-RET)from CdTe quantum dots(QDs)to Cy5 fluorophore was constructed for the determination of OTA.CdTe QDs film modified on the electrode was employed as the ECL donor,which could capture DNA through the cross linking of glutaraldehyde.The acceptor Cy5 modified with OTA aptamers could partially hybridize with the capture DNA.In the K2S2O8 coreactant,the ECL-RET between CdTe QDs and Cy5 made the ECL signal increased obviously.After incubated in the OTA solution,OTA aptamers removed from the electrode owing to the high affinity between the aptamer and OTA.As a result,ECL signal became weaker with fewer accepters left on the electrode.Under the optimized experimental conditions,the ECL intensity depended linearly on the OTA concentration at the range of 0.0005 to 50 ng·mL-1 with the LOD of 0.17 pg mL-1.The research results indicated that this method had high sensitivity and good selectivity,which provided potential application value for the OTA analysis of real samples.