| Electrochemiluminescence（ECL）is a technology combining chemiluminescence and electrochemiluminescence.ECL has many outstanding advantages,such as low background signal,high sensitivity and simple instrument operation,and is increasingly used in the field of pesticide residue analysis and detection.The most prominent feature of ECL is that it does not need external light source.The change of electrode potential and control the position and time of ECL emission have excellent sensitivity in the analysis and detection process.Sulfur quantum dots（SQDs）,as a new non-metallic quantum dot material in recent years,have become a research hotspot in the fields of cell imaging and biosensors due to their non-toxic,good water solubility,good biocompatibility and inherent antibacterial properties.In this paper,sulfur quantum dots with different colors were synthesized by two-step oxidation,assembly cracking and H2O2 post-etching.Their morphology,composition and structure were characterized and analyzed,and their ECL properties were further investigated.Based on the excellent ECL luminescence characteristics of sulfur quantum dots,the ECL sensor was constructed,and the signal closing strategy and signal amplification strategy were designed for the combination of nanomaterials.The detection method of pesticide residues was established.The main research contents are as follows:1.Construct an ECL sensor based on red luminescent sulfur point to detect malathion.Red luminescent sulfur quantum dots were synthesized by two-step oxidation.They were modified on the surface of the electrode as ECL phosphors,and then the complementary strand（c DNA）chain of malathion and the aptamer（Apt）were modified on the surface of the electrode to form a double helix structure.When the target malathion was modified on the sensor,the high affinity between the pesticide and the aptamer caused the aptamer to fall off the surface of the electrode.At this time,the electron mass transfer rate increased and the ECL signal increased.The detection of malathion was realized by the principle that the steric hindrance effect would limit the electron transfer on the electrode surface and the diffusion of co-reactants.The detection range of the constructed ECL sensor was 1.0×10-13-1.0×10-8 mol·L-1,and the detection limit was 0.043 pmol·L-1（S/N=3）.2.Construct an"signal-off"electrochemiluminescence sensor based on Fc-HPNs for the detection of acetamiprid.First of all,the negatively charged polyacrylic acid（PAA）and positively charged polyethylene imine modified ferrocene（PEI-Fc）were used to complete layer by layer enrichment on the surface of silica spheres by electrostatic self-assembly technology,and the silica spheres were etched by HF to form hollow porous polymer Fc-HPNs with Fc functional units.Secondly,blue luminescent sulfur quantum dots with good ECL luminescence properties were prepared by assembly-splitting method and post-etching method.In the system where sulfur quantum dots were used as illuminants and potassium persulfate was used as co-reactants,a signal closing strategy using Fc-HPNs as ECL signal quenching agent was designed to achieve highly sensitive detection of acetamiprid.The linear range of the constructed sensor was 1.0×10-14-1.0×10-7 mol·L-1,and its detection limit was 3.9 fmol·L-1（S/N=3）.3.Construct a novel electrochemiluminescence sensor based on Uio-66@SQDs for the detection of chlorpyrifos.In this work,Uio-66,which has excellent stability,large specific surface area and good catalytic properties,was selected as the carrier for adsorption of SQDs Uio-66@SQDs compound.Uio-66@SQDs complex showed stronger ECL emission compared with a single sulfur quantum dot as ECL phosphor.At the same time,the nano-flower structure with large surface area of Mo S2 was prepared by hydrothermal method,and Au NPs were introduced to form Mo S2@Au NPs composite improved its conductivity.Mo S2@Au NPs was modified on the electrode surface as the base material to increase the fixed amount of aptamers.The detection range of the constructed sensor for chlorpyrifos was 1.0×10-14-1.0×10-7 mol·L-1,and its detection limit was 2.6 fmol·L-1（S/N=3）. |
PDF Full Text Request