太空生存太空生存太空生存 (5).pdf
《太空生存太空生存太空生存 (5).pdf》由会员分享,可在线阅读,更多相关《太空生存太空生存太空生存 (5).pdf(9页珍藏版)》请在得力文库 - 分享文档赚钱的网站上搜索。
1、Effect of control mode on the sensitivity of a microbial fuel cell biosensorwith Shewanella loihica PV-4 and the underlyingbioelectrochemical mechanismYue Yia,b,c,Beizhen Xiea,b,c,Ting Zhaoa,b,c,Ziniu Qiana,b,c,Hong Liua,b,c,aBeijing Advanced Innovation Center for Biomedical Engineering,Beihang Univ
2、ersity,Beijing 100191,ChinabInstitute of Environmental Biology and Life Support Technology,School of Biological Science and Medical Engineering,Beihang University,Beijing 100191,ChinacInternational Joint Research Center of Aerospace Biotechnology&Medical Engineering,Beihang University,Beijing 100191
3、,Chinaa b s t r a c ta r t i c l ei n f oArticle history:Received 14 February 2019Received in revised form 1 April 2019Accepted 1 April 2019Available online 02 April 2019A relatively poor sensitivity is a critical challenge for the application of microbial fuel cell biosensors(MFC-bio-sensors).This
4、study investigated the effects of two control modes on sensor sensitivity and revealed theunderlying bioelectrochemical mechanism.The results demonstrated that the sensitivity of an S.loihica PV-4MFC-biosensor increased by 6.1 times when the anode was controlled at a constant potential(CP)instead of
5、being operated with a fixed external resistance(ER).This obvious difference in sensor sensitivity was partlyattributedtothemasking effectof theobservable offsetcurrentunderERmodeand thelower electricity produc-tion capacity under CP mode.Moreover,the analysis of metabolic structure showed that under
6、 CP mode the an-odic biofilm presented lower viability after toxic shock,due to a poorer ability to synthesize and secreteextracellular polymeric substances.Electrochemical measurements further revealed a lower capacitance underCP mode,which favored the permeation of Cd2+into the biofilm.2019 Elsevi
7、er B.V.All rights reserved.Keywords:Microbial fuel cellBiosensorControl modeShewanella loihicaBiofilm viability1.IntroductionAcute water pollutionis oneof themajor factors threateninghumansecurity.Early warning systems for water quality monitoring canachieve timely detection of toxic agents in the a
8、quatic environment,which is of significance for the assurance of public health.Traditionalwater quality monitoring is usually conducted using physicochemicalmethods.Though based on complex devices and complicated operationprocedures,these methods enable the accurate quantification of com-mon polluta
9、nts.However,they fail to reflect the biotoxicity of multiplecontaminants and are not suitable for insitu and online monitoring 1.Generic biosensors can compensate for the deficiencies of physico-chemical methods and have been extensively applied for water qualitymonitoring.Fish,algae,invertebrates a
10、nd bioluminescent bacteria arecommon testing organisms 2,as they can indicate the biotoxicity of awater sample based on changes in behaviors or in metabolic character-istics.Nevertheless,additional transducers whichcanconvert biologicalresponses to measurable electrical signals are indispensable to
11、thesebiosensors.This element,however,would increase the complexity andcost of these traditional biosensors.Recently,water quality monitoringbased on microbial fuel cell(MFC)technology,which uses an anodicbiofilm as the sensing and transducing element,simplifies the opera-tional process and is consid
12、ered to be a novel and promising candidatefor future application 3.The MFC is a device which can utilize electricigens as catalysts toconvert chemical energy from organic matter into electricity 4.When an MFC is used as a biosensor(MFC-biosensor),the presence oftoxic agents in the water sample will
13、alter or block the extracellularelectron transfer(EET)process of electricigens and further impact onMFCoutput.Hence,on-linemonitoringofwaterqualitycanbeachievedby tracking the voltage or current of an MFC-biosensor.The majoradvantages of the MFC-biosensor are high robustness and self-sustainability
14、due to the anodic biofilm serving as the sensing element5.However,usingsuchabiofilmassensingelementmightcausedete-rioration of sensor sensitivity to some extent.This is because the extra-cellular polymeric substances(EPS),which are essential to biofilmformation,play a critical role in the protection
15、 of microbes from toxicagents 6.Therefore,enhancing sensor sensitivity and addressing thislimitation is of significance for the application of the MFC-biosensor inreal world water monitoring.A great deal of research has been conducted to optimize the config-uration 7,8,shear rate 9,10,flow mode 11,e
16、xternal resistance 12and cathode/anode ratio 13 of the MFC-biosensor,which can partlyimprove sensor sensitivity.However,the operational parameters havediffered between MFC-biosensors and optimal performance might notbe generalized.The control mode is another key factor affecting sensorBioelectrochem
17、istry 128(2019)109117 Corresponding author at:School of Biological Science and Medical Engineering,Beihang University,37 Xueyuan RD,Haidian DIST,Beijing 100191,China.E-mail address:LH(H.Liu).https:/doi.org/10.1016/j.bioelechem.2019.04.0011567-5394/2019 Elsevier B.V.All rights reserved.Contents lists
18、 available at ScienceDirectBioelectrochemistryjournal homepage: is connected to an external resistance(ER)to form a closed circuit.Under this mode,a toxic event is monitored by tracking the change intheoutput voltageorinthecurrentacrosstheER 14,15.Anotheralter-native mode is to control the anode at
19、a constant potential(CP)andmeasure the current generated to monitor the toxic event.Stein et al.16 first proposed this mode and reported that the MFC-biosensorcould deliver better sensitivityunder CP mode.Similar results were fur-ther demostrated over a broad range of anode potentials and variouscor
20、responding resistances 11,which suggested that CP mode mightbe widely applicable for improving sensor sensitivity.Although,obvious enhanced sensitivity under CP mode was ob-served in both studies 11,16,the bioelectrochemical mechanism forthis difference has not been specified.A common phenomenon in
21、thetwostudieswasthatwhentoxicshockoccurred,theanodepotentialin-creased under ER mode while remaining unchanged under CP mode.Itwas speculated that four possible mechanisms,resulting from the in-creased anode potential,could possibly contribute to the different sen-sor sensitivities.Firstly,an offset
22、 current which could mask theinhibition of the electricity generation capacity of electricigens,mightdevelop under ER mode.Furthermore,the substrate consumption rateof electricigens could increase with the anode potential 17,and thusthe microbial activity as well as resistance to toxic agents would
23、be af-fected.Additionally,the extracellular electron transfer(EET)mecha-nism might also change with the anode potential 18,which couldresult in a changed capacity for power generation.Finally,the anodicdouble layer capacitance behavior could vary with the anode potential19;this might influence the p
24、ermeation of a toxic agent into theanodic biofilm.A combination of biological characterization andelectrochemical analysis might contribute to clarification of possiblemechanisms.Another issue in the previous studies was that the resultswere both based on mixed culture MFCs 11,16.Even under identica
25、lconditions,large individual differences have been revealed betweenmixed culture MFCs,so this type MFC was not suitable for a study ofmechanisms 4.Moreover,the researchers of both studies investigatedthe responses of MFC-biosensors to only one fixed concentration oftoxic shockagent,indicatinga lacko
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 太空生存太空生存太空生存 5 太空 生存
限制150内