Electrochemical Detection Of Heavy Metals Based On Yeast Nanocomposites

With the rapid development of industrialization and urbanization,discharging heavy metal ions（HM）pollutants（especially lead,mercury,cadmium,etc.）into soil,water and air has been widely recognized as a serious threat to the ecosystem.Cations are the most common form of HM.They get into humans or other organisms through the bioaccumulation and biotransformation in the food chain,and replace other substance in tissue structures,which may cause various diseases.Among of HM,lead ion is a dangerous substance in the aquatic ecosystem,which has been paid more and more attention because of the problems of anemia,muscle paralysis,memory loss and mental retardation.Therefore,it is urgent task to create a sensor for lead detection.In this paper,multi-functional yeast is used as a unit to specifically recognize Pb²⁺,and then three different nanomaterials are combined with yeast to increase the conductivity and specificity of the composite.Finally,the three sensors are applied to the human normal serum samples,showing superior stability,reproducibility and selectivity.The specific construction methods are as follows.（1）A minimally-disruptive portable electrochemical system is constructed by combining a hand-held syringe as reservoir with disposable screen-printed electrodes（SPEs）modified with a simple and efficient yeast/Co₃O₄/Au material for lead determination by a square-wave voltammetry（SWV）method.Not only can it preserve the operation and advantages of the conventional electrochemical procedure,but it also integrates sampling,filtering and analysis to make the determination of lead convenient and effective at higher and lower concentration levels.Additionally,the proposed system was used to determine lead in blood samples,which demonstrated the potential of this biosensor for use in practical applications.（2）A hydrothermal and ultrasonic method was used to synthesize the SG/CNT-COOH/MoS₂/yeast composites.Under optimal optimization conditions,The resulting calibration plot could be represented as y=34.69514-2.66888 lg C（C:pg/L,y:μA）with a correlation coefficient of 0.9981.Also,the work shows a wide log-linear dynamic range（LDR）from 10^-8 to 10^-14 g/L,with a limit of detection（LOD）of2.49×10^-15 g/L（S/N=3）.The prepared sensor has been applied to the actual blood test,and obtained a satisfactory recovery rate.（3）A electrochemical sensor based on SG/S-MoSe₂/Au/yeast composite is firstly synthesized via a novel hydrothermal route with large surface area and abundant binding cavities for synergistic effect on lead recognition.Due to the excellent conductivity of the Au nanoparticles and the specific recognition ability of the yeast,the SG/S-MoSe₂/Au/yeast/GCE sensor creates a better environment for the detection of lead,which facilitates the high sensitivity and selective identification of lead ions in solution.The results show wide liner range(10^-910^-14 g/L),low detection limit(0.85×10^-15 g/L（S/N=3）),good reproducibility（97.7%）and stability（97.2%）,acceptable recovery rate（96.23%¹07.29%）.The reseaches have shown that the three sensors prepared in this paper can achieve ultra-trace lead detection,which have reliability and portability in practical applications.