Fluorescent Probe Systems Based On Hyperbranched Polymers For High Resolution Recognition

The high-resolution recognitive system has the ability to detect trace components with specificity,accuracy,and efficiency.In fact,the high-resolution identification of food additives,environmental pollutants,and biomarkers by relying on this system will be directly related to many fields,such as food safety,environmental safety,and assessment of human health.However,many great challenges caused by the complex environment have restricted its development.In recent years,the signal-changed intelligent fluorescent probes have been reported to realize the high-resolution recognition of target substances with high sensitivity,fast response,and more convenience.Among them,integrating the multiple functions and stimulus responses,the fluorescent probe systems based on hyperbranched polymers show a great development prospect due to their three-dimensional globular structures,internal cavities,and abundant terminal groups.This thesis focuses on the design,preparation,and high-resolution recognitive application of the fluorescent probe system based on hyperbranched polymer.The main research contents and achievements are described as follows:（1）The hyperbranched probe TPE-HPAs efficiently recognizing pyrophosphate through“electrostatic interaction”:The water-soluble TPE-HPAs with AIE property were successfully prepared by Michael addition copolymerization.By electrostatic interaction,the probes could be used as fluorescence“turn-on”probes to detect pyrophosphate（PPi）in the absence of metal and organic solvent.TPE-HPAs also showed the ability of high-resolution recognition and nanomolar level LOD.（2）The hyperbranched probe TPE_4.1-HPA for sequential quadruple-target detection and its potential as a chemical logic gate:The probe that embeds tetraphenylethene（TPE）units into hyperbranched poly（amido amine）（TPE4.1-HPA）has been designed by using the same method in the above part 1.The nonfluorescent TPE4.1-HPA has the recognition ability with extreme sensitivity and selectivity,which could experience the fluorescence“off-on-off-on-off”by sequential addition of sodium hexametaphosphate（SHMP）,Fe³⁺,ascorbic acid（AA）,and H2O2 based on the aggregation and dispersion processof TPE molecules.In addition,on the basis of the multitarget sensing nature of TPE4.1-HPA,chemical or electrochemical-induced logic gates were constructed.（3）The hyperbranched probe TPE-HPA/RhB/PVA hydrogel accurately recognizing heparin:Rhodamine B（RhB）mixing with the water-soluble TPE-HPA was further introduced into the solid matrix of polyvinyl alcohol（PVA）hydrogel to form the ratiometric fluorescent test kit.Subsequently,by electrostatic interaction,the test kit shows the high-resolution detection of heparin（Hep）.It can also visualize the changes of fluorescent color under UV light.（4）The hyperbranched probe TPE-ssHPA specifically recognizing biothiol:Upon introducing disulfide bonds to TPE-HPAs,a series of AIE-active hyperbranched polymer probes were successfully synthesized（TPE-ssHPAs）.While in the presence of biothiol,the disulfide bonds in the ssHPAs are cleaved and the hyperbranched structure is dissociated,resulting in the aggregation of the TPE groups and turning on of the fluorescence.Further in vitro experiments verified that TPE-ssHPAs is a qualified probe for biothiol detection in living cells.（5）The hyperbranched probe TPE-ssHPA-AC@Au NCs sensitively recognizing CO₂:Acetamide-terminated TPE-ssHPA（TPE-ssHPA-Ac）was employed as a reducing agent and stabilizer to generate the water-soluble Au NCs via the bottom-up strategy,so as to construct the hyperbranched ratiometric fluorescent probe（TPE-ssHPA-Ac@Au NCs）with the dual emission nature.The probe can achieve the ratiometric detection of dissolved CO2 by the protonation processof the tertiary amine group,and the processcan also be reversible through the bubbling of the CO2/N2 stimuli.