New Electrochemical Nanosensors For Detection Of β-agonists In Livestock And Poultry Products

With the double improvement of people’s living standard and economic income,health and food safety are getting more and more attention.High-quality protein and abundant essential amino acids are found in livestock and poultry meat products.Unfortunately,some drug abuse problems are becoming the source of food safety.β-agonists is a kind of drug that can inhibit the fat production of animals and promote the growth of lean meat.In China,its uncontrolled use has seriously threatened people’s physical health and life safety.The establishment of a new method for the rapid and convenient detection of leptin has important theoretical and practical significance.In this study,an electrochemical nanosensor for one kind ofβ-agonists was first implemented to achieve rapid trace detection of the molecule.Then the improved sensor can detect two kinds of molecules at the same time.The portable electrochemical intelligent sensor established next not only improves work efficiency and simplifies the operation process,but also has high stability for the detection ofβ-agonists.Finally,the comparison between electrochemical nanosensors and HPLC provides data support for the widespread use of electrochemical nanosensors in livestock and poultry products.The specific research work is as follows:1.Trace detection of clenbuterol by electrochemical nanosensor and mechanism researchThe two-dimensional nanostructured phosphorene（BP）was treated with isopropanol（IP）and Nafion（Nf）to prepare nanocomposite modified glassy carbon electrode（GCE）.The electrode（BP-Nf（IP）/GCE）showed excellent electrocatalytic response to clenbuterol（CLB）.The morphology,structure,electrochemical active area and electrochemical stability of the composite electrode were studied.The results showed that BP-Nf（IP）/GCE has good electrochemical stability and electrocatalytic performance.The peak potential is0.94 V（vs.SCE）,the linear concentration range is 0.06-24μM,the limit of detection is3.7 n M（3σ/M）,and the sensitivity is 0.14μAμM^-1 cm^-2.Compared with the literature,the electrocatalytic overpotential is reduced,the sensitivity of sensing response is enhanced,and the detection range of linear detection is widened.The mechanism of electrocatalytic oxidation of CLB was proposed by density functional theory.Finally,the sensor has been successfully used in the electrochemical detection of CLB in beef and bovine serum samples,which has good feasibility and practicability.2.Simultaneous and rapid detection of clenbuterol and ractopamine by electrochemical nanosensorSingle（6-mercapto-6-deoxy）-β-cyclodextrin（S-β-CD）andpoly（3,4-ethylenedioxythiophene）nanoparticles（PEDOTNPs）were used to comodify two-dimensional nanomaterials BP,which were used to simultaneouslyβ-agonist CLB and ractopamine（RAC）by electrochemical method.The electrochemical modified electrode（S-β-CD-PEDOTNPs-BP/GCE）has the characteristics of high stability,strong antifouling ability,large electrochemical active area and good electrochemical response.In addition,the continuous cyclic voltammetry was used to further eliminate the pollution on the electrode surface through antifouling stratagem of electrochemical auxiliary materials.S-β-CD-PEDOTNPs-BP/GCE had the best current response to CLB and RAC at potential0.8 V and 1.0 V（vs.SCE）,respectively.Responses are linear in the 0.3-90μM concentration range for CLB,and from 0.3 to 9.4μM for RAC under optimal conditions.The limit of detection is 0.14μM and 0.12μM,respectively.The sensor was employed for simultaneous determination of CLB and RAC in（spiked）beef,feed and bovine serum samples with acceptable recoveries.3.Portable intelligent detection of clenbuterol by electrochemical nanosensorIn this paper,kudzu,a traditional Chinese medicine,was carbonized under controlled oxygen and high temperature to produce biochar,which was used as the modified material of flexible electrode.At the same time,the wireless intelligent sensor detection of CLB is realized by using the micro analyzer composed of smart phone and micro electrochemical workstation.The smart portable electrochemical sensor has the advantages of simple preparation,small volume,high stability,good repeatability and low cost.The sensor has a wide detection range of 0.95-14.31μM and a low detection limit of 0.75μM for CLB detection.In addition,the results show that the wireless intelligent portable sensor based on micro analyzer has the potential to realize the field detection of CLB.4.Comparative analysis of different detection methods of terbutalineA new electrochemical nanosensing electrode（Pd-Pt/COOH-Gra/Mo S₂/GCE）for the rapid detection of terbutaline（TRA）was developed by using two-dimensional materials Mo S₂,COOH-Gra and bimetallic Pd-Pt.The results of electrode surface morphology show that the modified material is thin-layer and bimetallic scattered,indicating that the sensor has strong electrocatalytic performance and large specific surface area,wide linear detection range of TRA is 0.44-43.37μM and low limit of detection is 0.22μM,which further confirms that the electrochemical nanosensor has high sensitivity to TRA.At the same time,the linear relationship of TRA was established by HPLC.The detection range is2.5-1400μM.Comparing the results of the two methods,we can see that the electrochemical sensor has a lower detection limit and is more sensitive than HPLC.At last,the recovery of TRA in beef and chicken is 98%-100.2%,which shows that the sensor based on the research scheme can provide method support for the effective detection of TRA.