Preparation And Properties Of AIE Luminescent Fluorescent Nanoparticles

In recent years,the strategy of aggregation-induced emission（AIE）has been widely applied in ion detection,drug delivery,bioimaging.Herein,two nanoparticles with aggregation-induced emission（AIE）characteristics were rationally designed and facilely prepared.Nanoparticles can be used as a drug carrier for drug release and also used as a fluorescent probe for the detection of iron ions in water.The morphology structure and fluorescence properties were characterized by fourier transform infrared spectroscopy（FT-IR）,atomic force microscope（AFM）,transmission electron microscope（TEM）,particle size analyzer,ultraviolet-visible spectrophotometer（Uv-vis）and fluorescence spectrophotometer.At the same time,the application in the controllable release of drugs and the detection of iron ions was analyzed.More specifically,the main contributions of this work can be described below.1.According to the characteristics of weak acidity and high concentration of H₂O₂in the tumor microenvironment.Drug carrier micellesβ-CD-（PNIPAM）₇@TPE-Fc with AIE effect was designed and constructed for stimulus-responsive release of drug and fluorescence monitoring.Thermosensitive polymerβ-CD-（PNIPAM）₇was firstly prepared as the host molecule.Afterwards,ferrocene carboxylic acid（Fc-COOH）was modified on the fluorescent molecule 1-（4-aminobenzene）-1,2,2-triphenylethylene（TPE-NH₂）to prepare the guest fluorescent molecule TPE-Fc.Novel nanoparticlesβ-CD-（PNIPAM）₇@TPE-Fc with multiple responses to temperature,pH and H₂O₂were fabricated by the host–guest interaction betweenβ-CD-（PNIPAM）₇and TPE-Fc.The nanoparticles exhibited excellent AIE optical properties.When the model drug doxorubicin（DOX）was entrapped in micelles,the fluorescent molecule TPE-Fc confers fluorescence to the micelles,which can realize fluorescence monitoring of drug release in a specific environment.In vitro release tests of DOX exhibited the pH,temperature and H₂O₂sensitivity.In the process of drug release,the drug sustained release process was monitored by detecting changes in the concentration of the drug solution and the fluorescence intensity in the dialysis bag.The drug diffusion mechanism is obtained by fitting the kinetic linear relationship between the cumulative release amount and time during the drug release process.2.In order to realize the determination of Fe³⁺/Fe²⁺in the green detection organism or the environment,a kind of“turn-off”type iron ion detection nanoprobesβ-CD-（PNIPAM）₇@TPE-Fc with AIE effect were designed.β-CD-（PNIPAM）₇@TPE-Fc has stable fluorescence properties can be used for the specific detection of iron ions without interference from other cations and anionsβ-CD-（PNIPAM）₇@TPE-Fc can be used for the detection of Fe³⁺and Fe²⁺in ultra-pure water.For Fe³⁺,the detection limits up to 1.04μM.For Fe²⁺,the detection limits up to0.78μM.Through the standard recovery experiment in water samples,the recovery rate is 92.25%-101.10%,and the relative standard deviation（RSD）is less than 0.72%,which verifies the feasibility in real water samples.By studying the mechanism of fluorescence quenching,it can be concluded that fluorescence quenching is caused by static quenching system.Therefore,β-CD-（PNIPAM）₇@TPE-Fc can be used as a convenient and green fluorescent probe for the detection of Fe³⁺in actual water samples.3.Using tetraphenyl ethylene derivative 4-（1,2,2-triphenylethenyl）benzaldehyde（TPE-CHO）as a fluorophore.It was modified on the chitosan（CS）chain by Schiff base reaction,and synthesized a macromolecular fluorescent material CS-TPE for detecting metal ions and bacteria in water samples.The results showed that the CS-TPE for detection of Fe³⁺has excellent sensitivity,selectivity,and reliability.For Fe³⁺,the detection limits up to 0.998μM.Through ion selectivity,ion interference,iron ion titration experiments and research on the mechanism of fluorescence quenching（Uv–visible spectrum）,the specific recognition performance of Fe³⁺was realized.Reliability was evaluated by recovery experiments in real samples using the standard spiking experiment,the recovery rate is 97.81%-102.48%,and the relative standard deviation（RSD）is less than 2.88%.The inhibition zone test demonstrated that the CS-TPE has an excellent antibacterial property against Staphylococcus aureus and Escherichia coli.After adding Staphylococcus aureus and Escherichia coli to CS-TPE solution,the fluorescence intensity was obviously quenched,indicating that it can be used as a fluorescent probe to realize the qualitative detection of Staphylococcus aureus and Escherichia coli.