Study On The Construction And Spectroscopic Properties Of Polyethyleneimine-based Fluorescent Probes

Fluorescent probe-based analytical technologies are indispensable approaches in environmental and biological sensing,and fluorescent probes could be divided into traditional conjugated molecules and emerging polymer nanoparticles.Traditional conjugated probes have good quantum yield,mature design routes,clear luminous mechanisms,and various fluorescent colors.However,using organic solvents,poor water-solubility,and high cytotoxicity are several fatal problems for these conjugated materials.In recent years,polymer nanoparticles,developed based on polymer matrix,could inherit the advantages of the matrix,such as excellent water solubility,biocompatibility,and high reactivity.Hence,developing polymer nanoparticles with good properties for various substance detection is critical.Based on the excellent water solubility,reactivity,and low toxicity,hyperbranched polyethyleneimine(h PEI)was used to prepare water-soluble probes with excellent fluorescent properties for the detection of copper ion(Cu²⁺),hypochlorite(Cl O^-),and cobalt ion(Co²⁺).The polymer PEI-HNA nanoparticles were synthesized between 6-hydroxy-2-naphthaldehyde(HNA)and h PEI through Schiff base reaction.In the second place,the dual-functional carbon dots PEI-DA was prepared by 2,4-dihydroxy benzoic acid(DA)and h PEI via hydrothermal reaction,which could be quantificational to detect Cu²⁺and Cl O^-in an aqueous solution.Thirdly,the sulfur-oxygen-doped polymer dots PEI-MA,which could detect Co²⁺in aqueous solution,was developed through h PEI and dimercaptosuccinic acid(MA).In addition to preparing these polyethyleneimine-based probes,the PEI-MA has been successfully applied to cell imaging,fluorescent dyes,test strips,nanofibrous films,and sensing hydrogels.The details are as follows:1.Through Schiff base reaction between amine groups of h PEI and the aldehyde groups of HNA in aqueous solution,the water-soluble polymer nanoparticles PEI-HNA was successfully synthesized.The PEI-HNA was utilized to detect Cu²⁺at 0?30?M,and the fluorescent quenching mechanism was attributed to electron transfer.PEI-HNA was conducted to bioimaging living cells with excellent cell penetrability and low toxicity based on the superior optical properties.The PEI-HNA had been doped into filter paper,hydrogel,and nanofibrous film to prepare solid-phase sensors,displaying rapid response and excellent sensitivity.Moreover,the low-cost and straightforward preparation of these sensors offered great potential and possibilities for industrialization,which could be conducive to accelerating the development of the sensors in environmental and biological fields.2.The bifunctional carbon dots PEI-DA was prepared through h PEI and DA via hydrothermal reaction and self-assembly in an aqueous solution.Using phenolic hydroxyl and amino as recognition sites,the PEI-DA could detect trace Cl O^-and Cu²⁺via fluorescent quenching.The quenching mechanisms to Cu²⁺and Cl O^-were ascribed photoinduced electron transfer(PET)and intramolecular charge transfer(ICT)effect,respectively.The PEI-DA was employed in He La imaging,fluorescent dyes,and portable sensors based on excellent optical properties.The PEI-DA-doped test strips and nanofibrous fluorescent films successfully monitored targets sensitively.The fluorescence hydrogel was further constructed to respond to targets rapidly and could effectively remove Cu²⁺in an aqueous solution through adsorption ability.These simple sensing techniques could be implemented as effective tools to monitor Cu²⁺and Cl O^-in environmental and biological samples.3.The polymer dots PEI-MA,which was synthesized through h PEI and MA via amidation reaction,could be used to monitor Co²⁺at 0?200?M.The blue fluorescence of PEI-MA could be quenched after adding Co²⁺,and the quenching mechanism was attributed to the complexation effect and static quenching.The low bio-toxicity and cell permeability were demonstrated by Hela cell imaging,indicating the PEI-MA with specific potential could be utilized in the field of biosensing domain.Meanwhile,the PEI-MA was employed in adjustable fluorescent dyes and the fabrication of portable solid sensors.PEI-DA-doped sensors,test strips,and nanofibrous fluorescent films with remarkable fluorescent performance could be used as effective monitoring devices to detect Co²⁺.Moreover,the dual-functional fluorescent hydrogels owned functions of detection and adsorption for Co²⁺in aqueous solution,providing an ingenious reference for the interdisciplinary research between fluorescent sensing and adsorption of Co²⁺.