Study On Aggregation-Induced Emission Materials Based On Polysaccharides

Aggregation-induced emission（AIE）is a special luminescence phenomenon,which is the opposite of aggregation-caused quenching（ACQ）.AIE materials emit strong fluorescence in solid-state or in bad solvents,while they do not emit light or emit weak fluorescence in poor solvents,which overcomes the defects of ACQ.Therefore,AIE materials have attracted much attention.However,most AIEgens are currently made from synthetic organic compounds.There are a large number of aromatic rings in their molecular structures,resulting in insolubility in water,bad biocompatibility,and bad degradability.Then,improving the water solubility and biocompatibility of traditional AIE materials is a hot spot.Polysaccharides are natural polymers with good water dispersion and biocompatibility.Combining polysaccharides with AIEgens through chemical or physical methods can not only improve the water solubility and biocompatibility of AIEgens but also broaden the application range of natural polysaccharides.Based on the above theoretical basis and research status,three novel AIE materials based on polysaccharides were fabricated in this work as follows.（1）Apositivelychargedkonjac glucomannan-graft-poly-（2-methacryloyloxyethyl）trimethyl ammonium chloride（KGM-g-PDMC）was prepared by using ceric ammonium nitrate as the initiator in an aqueous solution.Then,negatively charged copper nanoclusters（Cu NCs）were prepared by a one-step reduction method using glutathione as the reductant.Finally,the two precursors mentioned above were combined through electrostatic attraction to form a conjugate（KGM-g-PDMC/Cu NCs）exhibiting aggregation-induced emission（AIE）.The resultant products were characterized by Fourier transform infrared spectroscopy（FTIR）,zeta potential and particle size analysis,X-ray photoelectron spectrometry（XPS）,transmission electron microscopy（TEM）,and fluorescence spectrophotometry（FL）.The results showed that KGM-g-PDMC enhanced the AIE effect of Cu NCs,with an approximately 4-fold increase in fluorescence intensity.A cytotoxicity analysis showed that the products possess good biocompatibility.Moreover,cell imaging indicated that the products have the potential for application in the field of biomedicine.（2）KGM was oxidized by sodium periodate（NaIO₄）to form oxidized konjac glucomannan（OKGM）.Then,Amino-tetraphenylethylene（TPE-NH₂）with aggregation-induced emission（AIE）effect was synthesized using4-aminobenzophenone and benzophenone as raw materials.Finally,AIE active nanoparticles（KGM-TPE）based on KGM were synthesized by Schiff base reaction of OKGM with TPE-NH₂.The resultant samples were characterized by various means such as FTIR,solid-state nuclear magnetic resonance(¹³C NMR),XPS,differential scanning calorimetry（DSC）,X-ray diffractometer（XRD）,particle size analyzer,TEM,and FL.The results showed that the final KGM-TPE had amphiphilic features and could self-assemble into AIE-active nanoparticles.Thanks to the introduction of natural polysaccharide,KGM-TPE showed good biocompatibility.In addition,the results of excellent cell imaging and good anti-counterfeiting functions of KGM-TPE indicated that the obtained products had great potential in the fields of biomedicine and anti-counterfeiting.（3）The amphiphilic AIE nanoparticles（CD-TPE）were obtained by linkingγ-cyclodextrin（γ-CD）and 1,2-diphenyl-1,2-（p-hydroxyphenyl）-ethylene（OH-TPE-OH）by esterification reaction using hexamethylene diisocyanate（HMDI）in a one-step process.The CD-TPE was characterized by FTIR,¹³C NMR,DSC,XRD,particle size analyzer,TEM,and FL.The results not only confirmed the successful synthesis of OH-TPE-OH and CD-TPE but also confirmed the good water dispersibility and self-assembly of the obtained CD-TPE into AIE nanoparticles.The huge cavity of CD-TPE provided convenient conditions for the loading of adriamycin（DOX）and slow-release DOX with the loading and release rates of 67.4%and71.3%,respectively.The DOX release kinetic model was suitable for the Bhaskar model.Moreover,cytotoxicity analysis and cell imaging of CD-TPE were performed,showing that CD-TPE has good biocompatibility and excellent cell imaging performance.The above results indicated that CD-TPE has promising applications in biomedicine.