Electrochemiluminescence Aptamer Sensor Based On Novel Nanomaterials For Detection Of Heavy Metals

Heavy metal pollution causes serious harm to food and human health.Once heavy metals enter the human body,it is difficult to expel them.They can combine with proteins and degrade with difficulty,causing great harm to body health.Therefore,it is of great significance to establish a simple,rapid and accurate heavy metal detection method for ensuring food safety and human health.Due to the rapid development of industry and agriculture,water and aquatic products are polluted by a variety of heavy metals.At the same time,there are also other pollutants such as antibiotics and pathogenic bacteria.The detection of a single target can no longer meet the needs of human production and life,and it is urgent to establish a method of simultaneous detection of multiple pollutants to ensure food safety.To solve the above problems,this study uses functional novel nanomaterials to improve the electrochemiluminescence performance,and highly specific and aptamers as recognition components.With the help of cathode and anode luminous materials,a potential-resolved biosensor for synchronous detection of two kinds of pollutants is constructed,which can be used for the detection of heavy metals,antibiotics and pathogens in water and aquatic products.The main research contents and results are as follows:（1）Synthesizing MXene@gold nanoparticles（MXene@Au）and core-shell nanoparticles gold@silica（Au@Si O₂）,and an electrochemiluminescence biosensor with MXene@Au as the base and Au@Si O₂ as the signal amplification factor was constructed for the detection of Pb（Ⅱ）in water.The MXene@Au composite materials provides a good interface environment for the loading of ruthenium bipyridine(Ru（bpy）₃²⁺)on electrodes.Based on resonance energy transfer,Au（core）Si O₂（shell）nanoparticles can stimulate electron transport,promote the oxidation of tripropylamine（TPr A）,and improve the electrochemiluminescence intensity.In addition,the aptamer chain with high specificity recognition is used to specifically recognize Pb（Ⅱ）,and Pb（Ⅱ）activates the aptamer to exert its endonuclease activity,thus realizing the signal cycle amplification in the detection process of Pb（Ⅱ）.After adding Pb（Ⅱ）,the electrochemiluminescence signal was weakened.The concentration of Pb（Ⅱ）was detected according to the electrochemiluminescence intensity.In the range of 0.1～1×10⁶ ng/L,the minimum detection limit（LOD）of the aptamer sensor was 0.059 ng/L,the relative standard deviation（RSD）was 0.39%～0.99%,and the recovery was 90.00%～125.70%.The sensor was used to detect the heavy metal Pb（Ⅱ）in water.（2）Water pollution leads to serious pollution of aquatic products.Aquatic products are not only polluted by heavy metals,but also contain harmful substances such as antibiotics.Based on the previous chapter,an electrochemiluminescence analysis method for synchronous detection of two kinds of pollutants is established in this part.The specific surface area of the sensor is increased by using the flower-like bismuth sulfide@gold（Bi₂S₃@Au）as the substrate nanomaterial.Two kinds of independent electrochemiluminescence emission signals were introduced,namely gold@luminol（Au@luminol）and cadmium sulfide quantum dots（Cd S QDs）,to construct a biosensor for the simultaneous identification of Cd（Ⅱ）and ampicillin with double potential.Bi₂S₃@Au nanoflower has a high surface active area,accelerates the electron transfer rate,and provides a good interface environment for the load of luminous materials.The Au@luminol functionalized DNA2 probe was used as an independent luminous signal source at positive potential to identify Cd（Ⅱ）,and the Cd S QDs functionalized DNA3 probe was used as an independent luminous signal source at negative potential to identify ampicillin.The simultaneous detection of Cd（Ⅱ）and ampicillin at different concentrations were realized according to the changes of the electrochemiluminescence intensity of the two luminescence sources.In the range of 1×10^-3-1×10⁶ ng/L,the LODs of Cd（Ⅱ）and ampicillin were 3.42×10^-4 ng/L and 3.57×10^-4 ng/L,the recovery was 94.54%-119.18%,RSD was 0.37%-2.98%.The detection mechanism of two target substances was analyzed by the sensor,and the highly sensitive simultaneous detection of Cd（Ⅱ）and ampicillin in aquatic products was realized.（3）Aquatic products are contaminated by heavy metals and antibiotics,but also by pathogenic bacteria.Based on the research in the previous chapter,the synchronous detection methods of heavy metals and Staphylococcus aureus（S.aureus）in aquatic products were studied in this part,and a double potential resolved electrochemiluminescence sensor based on aptamer was constructed.Gold@Ni-Co metal-organic skeleton（Au@Ni-Co-MOFs）were synthesized to improve the surface active area and sensitivity of the sensor,providing more catalytic active sites for both functional probes.Sea urchin gold@luminol（Au@luminol）probe connected to aptamer DNA2 for specific recognition of Pb（Ⅱ）,Cd S QDs probe connected to aptamer DNA3for specific recognition of Staphylococcus aureus,and synergistic catalytic reduction of hydrogen peroxide via Au@Ni-Co-MOFs to generate electrochemiluminescence signals.The highly sensitive quantitative detection of Pb（Ⅱ）and S.aureus were realized by using double signals according to the different electrochemiluminescence responses caused by different concentrations of the two substances.The detection ranges of Pb（Ⅱ）and S.aureus were 1×10^-3-1×10⁶ ng/L and 0-1×10⁷ CFU/m L,and LODs were 1.9×10^-3 ng/L and 1.3 CFU/m L.The sensitive detection of heavy metal Pb（Ⅱ）and S.aureus in aquatic products was successfully realized.