A lipase-based electrochemical biosensor for target DNA

A Non‐enzymatic Hydrogen Peroxide Photoelectrochemical Sensor Based on a BiVO4 Electrode

“…Thee lectrochemicali mpedance spectroscopy (EIS) Nyquist plots of the electrode in the dark and under illumination in 0.10 MP BS containing equimolar K 3 [Fe(CN) 6 ]/ K 4 [Fe(CN) 6 ]( 0.25/0.25 mM) as the redox probe were recorded.T he experiment was conductedu nder open circuit potential conditionsi nafrequencyr ange between 10000 and 0.01 Hz and the applied amplitude was 10 mV. Ther adius of the arc reveals the charge transfer efficiency and charge separation efficiency between electrons and holes under illumination [ 42].F rom Figure 6, one can see that compared with that under the dark, the radius of the arc of the electrode under illumination decreasesd ramatically,w hich turns out that the electrode possess higher electron-hole separation efficiency and lower recombination rate under the light [43].…”

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1IntroductionHydrogen peroxide (H 2 O 2 )p lays an important role in many important fields,s uch as industry, pharmacy, food production and so on [1].E xcessive dosage of H 2 O 2 in the environment, however, may lead to such serious health problems as Alzheimers, diabetes,c ardiovascular disorders,c ancer, and concerned neurodegenerative diseases,t on ame but af ew [2].S o, an accurate, rapid and reliable method to detect H 2 O 2 is of great importance. Up till now,m any technologies have been developed for determiningt he concentration of H 2 O 2 ,s uch as fluorescence,s pectrometry,c hemiluminescence and chromatographict echniques [ 3].N evertheless,t hese technologies suffer from severald isadvantages.T hey are either timeconsuming,e xpensive or difficult to minimize.I nc ontrast, electrochemical analysisi sv alued because it is highly sensitive,e asy to minimize,r ealizable for in-situ detection; additionally,i ti so fl ow cost and of simple instrumentation [4].E lectrochemicala nalysis based on enzymed ecorated electrodes has been studied because of its good selectivity,f ast response and high sensitivity.H owever,e nzymes hold some intrinsic drawbacks,f or instance,t hey are unstable throught hermal environment, easy to lose activity when pH varies,e asy to get denaturedb yh eavy metals [5].T herefore,t he stability and reproducibility of the enzyme-based electrochemical sensor are undesirable [6].T hese drawbacks restrict the application of enzyme based electrochemical sensor [7].T hus,i ti sn ecessary to build enzyme-free electrochemical sensors with high sensitivity,l ow cost, and high stability towards the external environment.N owadays,m any nanomaterials that possess large specific surface area and high catalytic activity,s uch as semiconducting metal oxides [8],c arbon nanotubes [9],g raphene [10],t ransitionalm etallic nanoparticles [11] and so on, have been used to fabricate enzyme-freee lectrochemical sensors [ 12].H owever, the sensitivityo f these non-enzyme electrochemicals ensors remains undesirable due to the relatively high backgroundn oise.T hus, the development of an ew type of enzyme-free H 2 O 2 sensor is desired.Since the discovery of photoelectric effectb yE dmond Becquerel in 1839, photoelectrochemistry( PEC) has always been an attractive research fieldo ver the years. Photoelectrochemical process refers to photon-to-electron conversion caused by electron excitation and consequent charge transfer of photoexcited materials (usually organic or inorganic semiconductors) produced under illumination [13,14].P hotoelectrochemistryh as been applied in many fields such as photosynthesis,p hotovoltaics and photocatalysis.F or instance,p hotocatalytic synthesis of methanol from CO 2 and H 2 Oh as drawnm ore and more attention [15].C ombining photoelectrochemistry with analytical technology generates ab rand new field,t hat is, PEC sensor.

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“…Up till now,m any technologies have been developed for determiningt he concentration of H 2 O 2 ,s uch as fluorescence,s pectrometry,c hemiluminescence and chromatographict echniques [ 3].N evertheless,t hese technologies suffer from severald isadvantages.T hey are either timeconsuming,e xpensive or difficult to minimize.I nc ontrast, electrochemical analysisi sv alued because it is highly sensitive,e asy to minimize,r ealizable for in-situ detection; additionally,i ti so fl ow cost and of simple instrumentation [4].E lectrochemicala nalysis based on enzymed ecorated electrodes has been studied because of its good selectivity,f ast response and high sensitivity.H owever,e nzymes hold some intrinsic drawbacks,f or instance,t hey are unstable throught hermal environment, easy to lose activity when pH varies,e asy to get denaturedb yh eavy metals [5].T herefore,t he stability and reproducibility of the enzyme-based electrochemical sensor are undesirable [6].T hese drawbacks restrict the application of enzyme based electrochemical sensor [7].T hus,i ti sn ecessary to build enzyme-free electrochemical sensors with high sensitivity,l ow cost, and high stability towards the external environment.N owadays,m any nanomaterials that possess large specific surface area and high catalytic activity,s uch as semiconducting metal oxides [8],c arbon nanotubes [9],g raphene [10],t ransitionalm etallic nanoparticles [11] and so on, have been used to fabricate enzyme-freee lectrochemical sensors [ 12].H owever, the sensitivityo f these non-enzyme electrochemicals ensors remains undesirable due to the relatively high backgroundn oise.T hus, the development of an ew type of enzyme-free H 2 O 2 sensor is desired.…”

Tyramine Functionalized Graphene: Metal‐Free Electrochemical Non‐Enzymatic Biosensing of Hydrogen Peroxide

“…[12] Hence, these asfunctionalized graphene sheets have been successfully used as a metal-free catalyst for non-enzymatic biotransformation, which extraordinarily shows excellent biocompatibility and sensitivity. [13][14] Unfortunately, enzymatic biosensing is exceptionally complex process and some of the enzymes are having savior issues like stability at low and high pH, temperature, stickiness, selectivity, affectability, biocompatibility of enzymes. [15][16][17] To overcome these issues and further modulate the rate of transformation by using electrochemical methods for biosensing are proposed in the literature.…”

A light-responsive multienzyme complex combining cascade enzymes within a peptide-based matrix

“…[12][13][14] Cascade enzyme systems containing oxidases (such as glucose oxidase, urate oxidase and amino acid oxidase) and catalases are widely used in disease diagnoses, food processing and chemical synthesis. [15][16][17][18] In this study, we created a novel light-responsive multienzyme complex (GOx&hemin@PepM) by incorporating glucose oxidase (GOx) and hemin within the azobenzene modied peptide-based matrix (PepM). Hemin is the prosthetic group of catalase, which is an iron-containing porphyrin and can be used individually as a molecular catalyst.…”