Construction Of “Signal Off/on” Electrochemiluminescence Sensors Based On Nanomaterials And Its Applications

With the continuous progress of society,people have more awareness of environmental protection and healthy lifestyle,and have higher requirements for environmental testing,food health and medical diagnosis.It is of great significance and value to develop the detection device with high sensitivity,high selectivity and strong universality to realize the rapid and efficient analysis of the target.Electrochemiluminescence（ECL）refers to the introduction of electrochemical detection technology in chemiluminescence.The combination of the two detection technologies makes up for the disadvantages of uncontrollable chemiluminescence potential and short luminescence process,but also enhances the selectivity and sensitivity of the detection method.As a result,the technology has gained popularity among researchers in the fields of environmental testing,clinical diagnosis and food security.In order to realize sensitive detection of target,a series of nanomaterials with unique physicochemical properties such as CdS nanowires（CdS NWs）,Gold nanoparticles（Au NPs）,MoS₂quantum dots（MoS₂QDs）,versatile resorcinol-form-aldehyde resin（RF）,alkenylated lumino-gold（alyl-L-Au NPs）and so on were synthesized in this paper,and the highly sensitive ECL systems were constructed by combining nanomaterials and effective signal detection modes to achieve efficient detection of environmental pollutants(Hg²⁺)and biomglobin（Myo）and prostate-specific antigen（PSA）.The main innovation points and arkers myoresearch contents are as follows:1.An ECL sensor for mercury（II）detection was developed based on the precipitation conversion reaction caused by the difference of sedimentation equilibrium constant between CdS and HgS.To fabricate the sensor,CdS NWs serving as the emitter were introduced upon a glass carbon electrode（GCE）.Au NPs with excellent electrical conductivity were introduced on the surface of CdS NWs/GCE to enhance the sensor performance.In the presence of Hg²⁺,the ECL signal of the sensor decreased.The ECL intensity was negatively correlated with the concentration of Hg²⁺.The excellent performance of Au NPs:CdS NWs/GCE,combined with the difference in the CdS and HgS sedimentation equilibrium constants,endows the sensor with good selectivity and sensitivity for the analyte.A long linear range from 6.7×10^-15mol/L to1.0×10^-8mol/L was obtained for Hg²⁺with a detection limit of 5.0×10^-15mol/L.The applicability of the method was validated by the analysis of tap water and lake water,and the recoveries was 86.00%-104.4%.The sensor provides a simple and sensitive method for the detection of heavy metal ions,and shows a good application prospect in environmental detection.2.A novel“signal off”ECL immunosensor was constructed for the sensitive determination of Myo based on the multiple quenching mechanisms caused by the RF.In the sensing system,with MoS₂QDs as the energy donor and RF as the energy acceptor,an effective electrochemiluminescence-resonance energy transfer（ECL-RET）can occur between them,which would quench the ECL signal.Meanwhile,the catalysis of RF was activated to effectively convert dissolved oxygen to H₂O₂,which reacted with SO₄^·-produced by the decomposition of K₂S₂O₈to consume SO₄^·-,further reducing the ECL intensity of the MoS₂QDs/K₂S₂O₈system.In addition,RF has poor electrical conductivity,and its spatial potential resistance effect further caused the burst of ECL signal.The multiple bursts of RF on the ECL signal effectively amplify the ECL signal,which greatly improves the detection sensitivity of this sensing system and realizes the quantitative analysis of the target Myo.Under optimized conditions,the sensor system exhibited a low detection limit of 4.2×10^-14g/m L and a wide linear range of 1.0×10^-13-1.0×10^-9g/m L.The detection of Myo in human serum samples also showed good accuracy,with the recoveries of 90.0%-110%.On the one hand,the system avoids complicated operation caused by the introduction of exogenous quencher;on the other hand,the sensitivity of the sensor system is greatly improved through the synergic quenching of multi-mode,which provides a new idea for the construction of a novel“signal off”ECL sensor platform.3.Based on the light-induced alkene thiol click reaction,a“signal on”type ECL biosensing platform for efficient and rapid detection of PSA was developed by skillfully introducing alyl-L-Au NPs as the luminophor into the sensing system.The sensing platform used reduced graphene oxide（r GO）as the electrode interface,and Ab₁/PSA/SH-SiO₂-Ab₂was formed on the interface by sandwich immunoreaction.At the illumination at 365 nm,SH-SiO₂generated sulfhydryl radicals to attack-C=C-on alyl-L-Au NPs,transferring the active center to alyl-L-Au NPs and generating alkyl radicals to complete the addition of carbon-carbon double bond and realize the“on”transition of ECL signal.Under optimized conditions,the detection limit of the sensor is 3.5×10^-14g/m L,and the linear range is 1.0×10^-13-1.0×10^-7g/m L.In the actual sample analysis,the sensor also has good performance,and its recoveries was 88.0%-111%,which provides a new perspective for the construction of disease marker detection platform.