Switchable Self-powered Platform Based On Reversible Photo-Regulation Of Enzymes

Enzymatic biofuel cells(EBFCs)are a class of fuel cells utilizing redox enzymes as biocatalysts,which can realize the conversion of chemical energy into electrical energy.Due to its high catalytic activity,excellent biocompatibility,and the ability to use biomass for power generation,EBFCs have received widespread attention in the field of biomedicine,especially in artificial organs,implantable sensors,and wearable devices.In recent years,a new class of EBFC applications called self-powered therapy platforms(SPTPs)has achieved great success.By combining self-powered biosensing with drug-release ability,SPTPs can simultaneously realize the functions of disease diagnosis and therapy,showing great potential in real application.However,the existing EBFC-based SPTPs are still in the stage of in vitro application.One of the reasons is that the uncontrolled drug release process can cause unexpected damage to healthy tissues and organs.Achieving rapid,precise,and reversible regulation of drug release process is the key step in advancing SPTPs from in vitro application to in vivo application.In addition,SPBs based SPTPs are also facing the issues of low sensitivity,high detection limit,and narrow linear range.These defects limit the detection performance of SPTPs,making it difficult to be applied in diagnosing most of diseases.To improve the performance of SPTP to realize the application of SPTP in vivo,this paper is dedicated to developing new SPTP design schemes.We separately studied and optimized the two functions corresponding to SPTP — "therapy" and "diagnosis",in order to solve the problem of reversible regulation and sensitivity of SPTP.In the "therapy" section,we chose light as the external stimulus signal and used non-covalently modified acetylcholinesterase(ACh E)to prepare biocathode.The modified acetylcholinesterase can realize the on-off regulation of activity by irradiation of ultraviolet/visible light,thereby regulating the catalytic reaction of the biocathode.For the bioanode,we used a drug-loaded bilayer polymer polypyrrole/poly(N-methylpyrrole)to achieve drug-release and donation of electrons.After assembling the biocathode and the bioanode,we controlled the turn-off and turn-on of the output current and power of EBFC through the alternating irradiation of visible/ultraviolet light,so as to realize the regulation of the drug release process.In the "diagnosis" section,we studied the adsorption of redox enzymes on n-type semiconducting polymers and tried to apply them in constructing accumulation-mode organic electrochemical transistors(OECTs).OECT is a electronic that has excellent signal amplification ability and does not require high voltage to operate.By using OECT,we tried to design a sensing device that can be applied to SPTP to improve its sensitivity.Chapter 1 IntroductionAt the beginning of this chapter,we reviewed enzymatic biofuel cells,mainly including EBFCs’ history,working mechanism,electrode materials and modification methods,practical applications and existing methods to regulate enzymatic biofuel cell.In addition,advancements in the field of regulation of enzyme activity are briefly reviewed.Finally,the significance and contents of our paper were proposed.Chapter 2 Switchable self-powered drug release platform based on lightregulated enzyme cascade reactionIn this work,we constructed an enzymatic biofuel cell based self-powered drug release platform through light-regulated enzyme cascade reactions.By coimmobilizing photoswitchable acetylcholinesterase,choline oxidase(Ch Ox)and horseradish peroxidase(HRP),we obtained a biocathode that can be regulated through light.In the bioanode,we used a bilayer polymer polypyrrole/poly(Nmethylpyrrole),which was used for providing electrons and releasing drug simultaneously.By illuminating the biocathode,we realized the on-off regulation of the output current and power of the fuel cell,as well as the release of drug at bioanode,proving the feasibility of constructing an on-off self-powered therapy platform based on the regulation of the enzyme cascade reaction.Overall,we proposed a solution for the regulation of the self-powered therapy platform.Chapter 3 Ultrasensitive lactate detection based on n-Type semiconducting polymer and organic electrochemical transistor(OECT)As presented in chapter 2,we realized the controlled drug release of selfpowered therapy platform.In this chapter,we further researched the way to improve the sensitivity of self-powered therapy platform.Self-powered biosensors(SPBs)based on enzymatic biofuel cells generally suffer from poor sensitivity,making it difficult for them to be applied in diagnosing most of diseases.To solve this problem,it is necessary to develop a more sensitive detection method with a lower detection limit and broader linear range.Organic electrochemical transistor(OECT)is a kind of device that conducts through ions,which is not only easy to miniaturize,but can also realize ultrasensitive substance detection through the change of source-drain current.In this work,we are committed to realizing the detection of lactate based on organic electrochemical transistors.By modifying n-type semiconducting polymers that can realize fast electron transfer,we tried to build an accumulation-mode organic electrochemical transistor detection platform,used for improving the detection performance of the self-powered therapy platform.