Synthesis,property And Analytical Application Of Reactive Oxygen Species-Responsive Chemiluminescent Nanomaterials

In this dissertation,the basic concepts of chemiluminescence(CL),principles of CL analysis,common CL systems and catalysts were briefly introduced.The state of arts about reactive oxygen species(ROS)stimuli-responsive materials was reviewed.Stimuli-responsive materials have received extensive attention in the past decade due to their precise and controllable characteristics,high sensitivity,good specificity,and ease of design and assembly.Currently,single and multiple stimuli-responsive materials have been used in emerging and important fields such as biomedicine,information technology,catalysis,and intelligent interfaces.However,except for peroxalate nanoparticles,other stimuli-responsive CL functionalized materials have rarely reported.In this thesis,a novel stimuli-responsive chemiluminescent nanocomposite(Co-AuNCs-ABEI@Oxi-Dex Nanocomposites)based on CL-functionalized bimetallic nanoclusters(GSH@Co-AuNCs-ABEI)encapsulated in boronic ester modified dextran nanospheres(Oxi-Dex)was synthesized.The morphology,composition,CL property and mechanism of the as-prepared nanocomposites were studied.On this basis,an ultra-sensitive,selective reagent-free and enzyme-free CL sensor was developed for H2O2 detection.The main research contents are as follows:Firstly,a facile strategy for preparing Co-AuNCs-ABEI@Oxi-Dex nanocomposites was developed.In this strategy,Co/Au bimetallic nanoclusters(GSH@Co-AuNCs)were successfully synthesized using glutathione(GSH)as reduction-cum-protection reagent,and then ABEI molecules were attached on the surfaces of GSH@Co-AuNCs to obtain CL functionalized nanoclusters(GSH@Co-AuNCs-ABEI).The ROS-sensitive dextran chains(Oxi-Dex)were obtained through the connection of the boronic ester groups(PBAP-CDI)with the hydroxyl groups in dextran,and then GSH@Co-AuNCs-ABEI and Oxi-Dex self-assembled under the control of hydrophobic interaction.The morphology,composition and optical properties of GSH@Co-AuNCs-ABEI and Co-AuNCs-ABEI@Oxi-Dex nanocomposites were investigated by X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,fluorescence,transmission electron microscopy,etc.The results showed that the nanocomposites were roughly spherical with a core-shell structure with an average size of 182.56 nm.The inner core was composed of GSH@Co-AuNCs-ABEI.At room temperature,HAuCl4 and CoCl2 were coordinated with the thiol groups or other functional groups of GSH as well as some free anions in the reaction solution to form Co(?)-Au(?)-thiolate complexes and Co(?)-Au(?)-X complexes(X represents non-thiolate ligands),respectively.Subsequently,at an elevated temperature of 70?,the Co(?)-Au(?)-X complexes were selectively reduced to Co(0)and Au(0)nanocores,which were further sequestrated by the Co(?)-Au(?)-thiolate complexes to form the Co(0)Au(0)@Co(?)Au(?)-thiolate intermediates.The Co(0)Au(0)@Co(?)Au(?)-thiolate intermediates gradually aggregated to form the Co(0)-Au(0)nanocores enclosed by the Co((?)Au(?)-thiolate complex shell structure.Eventually,the ABEI molecules were immobilized on the carboxyl groups of Co(?)Au(?)-thiolate shell through covalent bonds.The CL properties of the as-prepared nanocomposites were studied through a microplate luminometer.It was found that in the presence of H2O2 both GSH@Co-AuNCs-ABEI and Co-AuNCs-ABEI@Oxi-Dex nanocomposites exhibited strong CL signals,which increased by 564 times and 128 times compared with that of the same concentration of ABEI solution.Maximum emission wavelength of these two nanocomposites was 460 nm,which was consistent with that of the ABEI solution,indicating that the CL emission of all the two systems originated from the excited state of the ABEI.With H2O2 as the representative ROS,the response performance of Co-AuNCs-ABEI@Oxi-Dex nanocomposites to ROS stimulation was also explored by dynamic light scattering and cryo-electron microscopy.After adding H2O2,the nanocomposites decomposed,transforming from monodisperse spheres to merged configurations,resulting in a significant increase in size.Moreover,the CL mechanism of Co-AuNCs-ABEI@Oxi-Dex nanocomposites-H2O2 system has also been proposed.Both Co(?)and Au(0)in GSH@Co-AuNCs-ABEI could promote the decomposition of H2O2 to generate radicals,and Au(0)as well as bimetallic nanoclusters could accelerate the transfer of electrons,thus an excellent CL signal was observed.However,Oxi-Dex was oxidized to form phenol and subsequently participated in quinone methylation rearrangement when it was specifically stimulated by H2O2,the CL intensity of the Co-AuNCs-ABEI@Oxi-Dex nanocomposites decreased and the monodisperse core-shell configuration was destroyed.Based on the excellent CL performance and selectivity to H2O2 of the nanocomposites,we developed a novel reagent-free and enzyme-free H2O2 sensor with a wide linear range of 0.1 nM to 10.0 ?M as well as a low detection limit of 93.0 pM.The sensor is stable,sensitive and selective,which could be used for the determination of H2O2 in real human serum samples.It is of great application potential for the determination of ROS related to various diseases.Alternatively,the proposed assembly strategy for the ROS stimuli-responsive CL nanocomposites may also be utilized as a template to be adapted for the synthesis of other ROS stimuli-responsive CL nanocomposites for CL-guided disease treatments.