The Construction Of Self-powered Whole-cell Biocathode Electrochemical Sensor And Their Application

In recent years,with the rapid development of China’s economy and society,the problem of environmental pollution has become increasingly prominent and has become a key factor affecting people’s quality of life and health status.Therefore,it is particularly important to carry out environmental assessment and toxicity risk warning.As an emerging detection technology,the whole-cell electrochemical biosensors based on electroactive bacteria(EAB)have advantages such as no complicated sample pretreatment,on-line continuous monitoring and uncomplicated signal conversion,etc.,and have developed rapidly in recent years.At present,they can effectively detect many environmental pollutants.However,the traditional whole-cell electrochemical biosensors need external power supply(such as potentiostat)to realize the detection of target objects,which is not conducive to their practical application.In fact,the whole-cell electrochemical biosensors usually do not require much energy to complete their sensing process.There are a lot of energy in the environment,such as solar energy,electromagnetic wave,biomass energy and so on,which can meet the energy demand.Therefore,we consider collecting the energy in the environment to power the sensor,combining the energy supply system and the biosensor system to develop a self-powered whole-cell electrochemical biosensor.According to the above ideas,Shewanella oneidensis MR-1,an electroactive bacteria mode strain,was used as a biocathode recognition element to construct a biocathode electrochemical sensing platform powered by microbial fuel cell(MFC).A simple voltage regulation strategy was proposed to dynamically control the potential of the biological cathode electrode,and the overall equation of the reaction rate of the biological cathode was established.Then,the sensing platform was used to realize the quantitative detection of nitrate in water.In addition,we have also preliminarily constructed a photo-powered biosensor,and explored the possibility of detecting fumarate,nitrate and 1-hydroxyphenazine.The research results of this article are summarized as follows:1)The Shewanella oneidensis MR-1 bicathodic reduction of nitrate was explored.A whole cell biosensor powered by microbial anode was constructed.The performance of the sensor was studied and optimized,and the quantitative detection of nitrate was realized.The minimum detection limit(LOD,S/N=3)was 0.32μM,and the sensitivity was 0.683μA/μM.2)A biocathode electrochemical sensor powered by series MFC was constructed.Through theoretical simulation and experimental verification,a voltage regulation strategy was proposed to dynamically control the potential of the biocathode electrode.The quantitative detection of nitrate was realized,and a new method of nitrate detection was developed.Compared with a single MFC power,the current response of nitrate is increased by about 3 times.The detection limit(LOD)(S/N=3)was 0.11μM,and the detection sensitivity was 1.97μA/μM.The self-powered biosensor has high selectivity and good anti-interference ability,and has been successfully applied to the detection of real water samples,showing high accuracy and reproducibility.3)A photo-powered biocathode electrochemical sensor was constructed to realize the quantitative detection of fumaric acid,nitrate and 1-hydroxyphenazine(POH).In the concentration range of 100μM to 0.5 m M,the peak area showed a good linear relationship with fumarate concentration(R~2=0.9855).There was a good linear relationship between the peak area and nitrate concentration in the range of 5μM～0.5m M(R~2=0.9950).In the range of 5 n M～0.5μM,the increase of current showed a highly linear relationship with POH concentration(R~2=0.9993).In summary,this study constructed two self-powered whole-cell biocathode electrochemical sensors with good detection performance,and proposed a simple dynamic voltage control strategy with external resistance.It provides new ideas for the online continuous monitoring of environmental pollutants,and is expected to promote the practical application of bioelectrochemical sensors in the field of environmental monitoring.