Electrochemiluminescence Sensor Based On Carbon Dots-covalent Organic Framework For Determination Of Emerging Contaminants

Covalent organic frameworks（COFs）are a class of crystalline porous materials.Ordered open channels and pre-designed regular structures enable COFs to have customized functions.In addition,COFs have the advantages of large specific surface area,regular and uniform pore channels,and high crystallinity,which have attracted considerable attention in the field of electrochemiluminescence.However,most COFs are connected by imide bonds,which may induce non-radiative relaxation mediated self-quenching,which becomes a major obstacle to the synthesis of luminescent COFs.In this study,we used carbon dots（CDs）as structural units to construct carbon dot Covalent organic frameworks（CD-COF）materials as luminescent materials for ECL.Compared with the CDs/S₂O₈^2-system,the ECL signal of CD-COF/S₂O₈^2-/Bu₄N⁺was expanded by 7.5 times,indicating that CD-COF can be used as a new type of ECL emitter.Subsequently,an ECL sensor for detecting new pollutants was developed based on the CD-COF luminescent materials.The main research content and innovation points of this paper are summarized as follows:1.Synthesis and electrochemiluminescence properties of CD-COFFirst,aldehyde-based carbon dots were synthesized using glutaraldehyde as raw material by solvothermal method.Then,using CDs as structural units and1,3,5-tris（4-aminophenyl）（TPB）as organic precursors,CD-COF was synthesized by condensation.Based on x-ray powder diffractometer（XRD）characterization,the influencing factors in the synthesis,such as solvent,ligand ratio,acetic acid volume,acetic acid concentration,and synthesis time,were gradually optimized to determine the optimal experimental conditions.The luminescence performance of CD-COF was explored.Based on the[Ru（bpy）₃]²⁺system（with a ECL efficiency of 5%）,the ECL efficiency of CD-COF/S₂O₈^2-/Bu₄N⁺was 25.12%.2.A carbon dot-based nanoscale covalent organic framework as a new emitter combined with a CRISPR/Cas12a-mediated electrochemiluminescence biosensor for ultrasensitive detection of bisphenol AThis chapter designed an ECL biosensor platform for ultrasensitive detection of bisphenol A（BPA）based on CD-COF.With CRISPR/Cas12a’s trans-cutting of arbitrary non-specific single chains and the energy resonance transfer between ferrocene（Fc）and CD-COF,an"off-on"ECL sensor had been constructed.The proposed ECL biosensor exhibited excellent performance with a wide linear range from 1.0×10^-14 mol/L to 1.0×10^-5 mol/L with a low detection limit of 2.21 f M（S/N=3）under the optimized conditions.Then used for the detection of BPA in actual water samples,with spiked recoveries ranging from 91%to 110%.3.Molecular imprinting electrochemiluminescence sensor based on CD-COF for dual mode detection of sulfadiazineThis chapter used CD-COF to emit ECL signals,and used molecular imprinting polymers（MIP）to specifically identify the target substance sulfadiazine（SDZ）.A dual mode MIP-ECL sensor was constructed by combining ECL and differential pulse voltammetry（DPV）.The linear ranges of ECL and DPV were 5.0×10^-9 mol/L～2.0×10^-4mol/L and 5.0×10^-8mol/L～2.0×10^-4 mol/L,respectively,the detection limits were 0.28 n M and 1.6 n M,respectively.The dual-mode sensor platform also showed excellent selectivity,reproducibility and stability for the detection of SDZ in milk and pork,with spiked recoveries ranging from 91%to 110%.