Synthesis Of Molecules With Aggregation-induced Emission Characteristics And Their Application In Bioimaging By Nanoparticies

Optical bioimaging technology is one of the largest growth areas in the biologicaland biomedical research. It provides a direct visualization tools for life scienceresearch and disease diagnosis, which is of important significance. Organicfluorescent molecules based on aggregation induced emission (AIE) have recentlyreceived extensive attention in the area of biological imaging. Especially the highbrightness fluorescent nanoparticles, based on AIE molecules, have shown goodprospects in biological imaging. In this thesis we designed and synthesized a series ofAIE fluorescent molecules that based on9,10-divinyl anthracene (DSA) andexplored their application in biological imaging by nanoparticles. The main researchcontents are as follows:1. A kind of Folic acid-functionalized mesoporous silica nanospheres hybridizedwith DSA luminogens was fabricated. The nanoparticles have a core-shell structure.The DSA fluorophore with AIE property was concentrated in the core of thenanoparticles, with a mesoporous silica protective shell outside. The fluorescence ofnanoparticles could be enhanced by increasing the concentration of the DSA, withoutthe risk of quenching. The nanoparticles are of small size (diameter~60nm),monodispersed and stable in aqueous suspension because of a large number ofnegative charges on the surface. According to the cell imaging experiments(nanoparticles incubated with HeLa cells or mice preadipocytes cells), we found thatthe folic acid-functionalized nanoparticles have the ability to identify cancer cells andcan be utilized for targeted HeLa cell imaging. In addition, the nanoparticles aremesoporous and therefore can potentially be used as vehicles for controlled, externally activated release of anticancer drugs.2. A kind of dendritic AIE fluorescent molecule was designed and synthesized baseon DSA. By connecting it with two kinds of donor-acceptor type molecules, twokinds of fluorescent molecules with near-infrared emission were synthesized. One ofthem is AIE behavior, and the other one is aggregation induced quenching (ACQ)behavior. The season why they have AIE property or ACQ property was analyzed bystudying their photophysical properties. A kind of micelle nanospheres was fabricatedby using the AIE fluorophore and PS-PVP which is a kind of amphiphilic blockcopolymer. The nanospheres The nanoparticles are of small size (diameter~25nm),monodispersed and stable in aqueous suspension. The nanoparticles have strong redemission and the emission peak located at643nm. The fluorescence quantum yield ofthe nanoparticles increased with the dye loading amount, and it can reach12.9%witha10%dye loading amount. The nanoparticles can be applied in red fluorescentbioimaging. After incubated with HeLa cells, the nanoparticles can enter thecytoplasm and nucleus and give intense red fluorescence signal. Therefore thenanoparticle have good prospects.