Construction And Application Of Fluorescent Probes For Reactive Oxygen Species Based On Boronic Acid Ester

Oxygen?O₂?is necessary for all aerobic organisms,which can be converted into a number of species in the presence of enzymes or metal ions.One class of these species is reactive oxygen species?ROS?.ROS includes hydrogen peroxide?H2O₂?,hydroxyl radical?·OH?,superoxide anion?O₂·-?,singlet oxygen?1O₂?,peroxy radicals?ROO?,hypochlorite and hypochlorite?HOCl/-OCl?,etc.Numerous studies have shown that ROS are important signal molecules in the life activities.However,excessive ROS can lead to the accumulation of oxidative damage,which may lead to apoptosis,aging,cancer and other diseases.H2O₂ is an important ROS,which is relatively stable compared with other ROS.In normal state,the concentration of H2O₂ is very low in cells.While excessive H2O₂ will react with metal ions?e.g.Fe2+,Cu2+?to produce ·OH,which could cause cellular dysfunction.O₂·-acts as an important precursor of other ROS.Therefore,exploring effective methods to detect H2O₂/O₂·-has always been one of the research focuses.Fluorescence analysis has become a hot topic in recent years due to its advantages of simple operation,high sensitivity and good selectivity.Ratiometric fluorescent probes have strong anti-interference ability,because its response signal is the ratio of two wavelengths,which can effectively prevent the background interference and improve detection sensitivity.Based on the above background,we synthesized the fluorescent probes based on boric acid ester to achieve the ratiometric detection of H2O₂ and the bifunctional detection of O₂·-sensitively.At the same time,based on the enzyme catalytic oxidation reaction,the nanoprobe can be used to detect biological matrix?such as,glucose,choline,cholesterol,lactic acid?.Furthermore,the detection of glucose in serum was achieved by using the nanoprobe.Chapter 1.IntroductionIn this chapter,we first introduced the production and function of ROS with the research progress of H2O₂/O₂·-in recent years.Then,we presented some knowledge about polymer micelles.Finally,we gave the purpose and significance of our research work.Chapter 2.Fluorescence probe based on ARS-boronic ester derivatives for the detection of H2O₂In this chapter,we utilized ARS which fluorescence can be increased by the combination with phenylboronic acid derivatives and quenched upon reaction with H2O₂ to realize the selective detection of H2O₂.Firstly,we prepared the fluorescent probes by using phenylboronic acid derivatives and ARS.Secondly,after the probes reaction with H2O₂,we tested the UV absorption spectra and fluorescence emission spectra.The results showed that the sensitivity of fluorescent probes to H2O₂ was depending on diverse substituents of the phenylboronic acid derivatives.We chose ARS-4-carboxy-3-fluorophenylboronic acid?ARS-FPBA?which has the maximum response to H2O₂ for quantitative analysis.In addition,this probe has good selectivity for the detection of H2O₂.Chapter 3.A self-assembled ratiometric polymeric nanoprobe for highly selective fluorescent detection of hydrogen peroxideIn this study,we constructed a kind of ratiometric fluorescent probe based on polymeric micelles.Firstly,we conjugated FPBA and 7-hydroxycoumarin?HC?on 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino?polyethylene glycol?]?DSPE-PEG-NH2?polymer,forming DSPE-PEG-FPBA and DSPE-PEG-HC.PEG-FPBA and PEG-HC are hydrophilic moieties,DSPE is the hydrophobic one.When the polymer were added to the water phase,they can self-assemble to form micelles.After mixing the micelles with ARS,ARS would bind to the surface of micelles automatically due to the interaction of ARS with FPBA.Upon excitation at 405 nm,the fluorescence emission peaks of HC and ARS-FPBA are at 450 nm and 600 nm.The absorption peak of ARS-FPBA is at 455 nm,which is perfectly overlapping with the emission peak of HC?450 nm?.Therefore,the fluorescence resonance energy transfer?FRET?could occur between HC and ARS-FPBA.However,ARS would dissociated from the micelles when incubated with H2O₂.In the presence of H2O₂,the fluorescence at 450 nm was attributed to HC increases,while the fluorescence at 600 nm ascribed to ARS-FPBA continuously decreases,thereby providing the ratiometric response to H2O₂.Moreover,we have achieved the highly selective detection of glucose in serum.Chapter 4.Synthesis of bifunctional probe with fluorescence/colorimetry assays and their sensitive detection for O₂·-In this work,we synthesized a new type of bifunctional probe through combining phenylboronic group with dicyanomethylene-4H-benzopyran?DCM?,which can be used to detect O₂' by fluorescence/colorimetry assays.This bifunctional probe has high sensitivity and selectivity for the detection of O₂'-.Firstly,we synthesized the probe DCM-PBA by the condensation reaction between methyl group and aldehyde group.Secondly,we measured the response of DCM-PBA to O₂·-.After interaction with O₂·-,the absorption at 560 nm was enhanced and the color of the solution changed from yellow to blue.Meanwhile,the fluorescence emission intensity at 700 nm was gradually enhanced upon excitation of 560 nm.Therefore,it can realize the detection of O₂·-by both colorimetric and fluorescent methods.