| Nanoparticles are sized between0.1and100nanometers,which are in thetransition zone between microscopic and macroscopic, and develop novelproperties that different from the bulk material and molecules (atoms). Compared toinorganic nanoparticle systems, organic ones are still needed more exlporation ontheir properties and formation mechanisms. However liquid phase synthesis methodoffers a board study platform for the research on oganic nanoparticles.Reprecipitation method is a way to fabricate organic nanocrystals in situ basedon solvent exchange, which has many advantages, such as easy and time-saving toprepare. It is an effective way to investigate on the properties and formationmechanism of organic nanocrystals and contributes to the knowledge on the organicnanocrystals. In our experiments, it is founded that stable water-dispersednanoparticles based on an amorphous molecule DPA-TSB can be fabricated byutilizing the reprecipitation method. We try to analysis the formation mechanism oforganic naoparitlce in water from the features of the amorphous molecules. Theimproved reprecipitation method where a new procedure named―dialysis process‖was introduced in the fabrication system. Therefore, the whole fabricated processwas divided into three procedures in details, which is reprecipitation procedure,aging procedure and dialysis procedure, respectively. We focus on the nanoparticlefabrication process base on the amorphous DPA-TSB of cruciform configuration,which help us to deeper understand the formation mechanism of nanostructure inthe reprecipitation process. We succeeded in fabricating water-depressed nanoparticles, and the average size of NPs can be controlled from50nm to100nmvia adjusting reprecipitation conditions. It is found that the optical physicalproperty was between that of molecules in dilute solution and spin-coating film,which exhibit that a similar monomolecular absorption and solid emission offluorescence similar to film. It was explained that the molecular stacking in thenanoparticle was disorder under the rapid aggregation conditions, because the weakmolecular interactions between molecules. However, the molecular interactions andnon-radiation transition enhanced during the excited state were enhanced due to theexcessive molecule accumulation, which lead to a red shift fluorescence emissionand photoluminescence decrease.Moreover, it was found there is a soft nanoparticle existing in thereprecipitation process which has nanostructure, can be dispersed in the mixture ofwater and tetrahydrofuran, but cannot retain intact under centrifugal force.Followed by the dialysis process, the soft nanoparticle was changed into hardmolecules, which comprised of more stable nanostructures and can be dispersed inwater. This water-dispersed capability of DPA-TSB nanoparticle lay the foundationof its further bioapplication. Finally, nanostructures were fabricated via differentanalogy molecules, and their morphologies and surface potentials are studied. Thecolloid stabilities in water of nanostrutures are explained qualitatively according toclassical DLVO (Derjaguin-Landau-Verweey-Overbeek) colloid stability principle,which implied that molecules of bulky steric combination and weak molecularinteractions are contributed to reduce molecular growth on a preponderancedimensional and are in favour of their colloid stability in water.We call this water-dispersed nanoparticle just by self-assembling of dyes as―bare nanoparticles‖to differ from dye-capsulated nanoparticles such as siliconnanoparticles, dye-coated with surfactant nanoparticles and so on. In our researchwork, these bare nanoparitcles apply for bioimaging are studied in detail. Firstly,the nanoparitcle can be uptake by different type of human tumor cells in vitro, suchas human gastric cancer and human cervical cancer cells, and can exhibit excellentlive cell stain capabilities as well as imaging effect under confocal fluorescentmicroscope. The cytoxity of DPA-TSB nanoparticle were particularly studied. It isfound that the bare nanoparticle do not restrain cell proliferation, which was detected by the WST-1viability assay. The effect on the cell membrane about thenaoparticle was analyzed through LDH release monitoring and found there is adose-time effect on the cell number of cells damaged or lysed. Then, cell cyclestatus and apoptosis in gastric cancer cell (SGC7901) in the present ofnanoparticles was investigated by flow cytometry, which indicated that at lowconcentration of nanoparticles (below2.4μg mL-1), there was no evident effect onthe cell cycle in the present of nanoparticles. When the concentration ofnanoparitcles was added above2.4μg mL-1the G0/G1stage of the cell cycle wouldbe affected, and the S stages would also be affected if the concentration went onincreasing, and there was a dose-time effect. When we tried to analysis the lowcytotoxicity of the bare nanoparticle, we found that the DPA-TSB molecules didnot evident cause a suppressing effect on cell survival at the concentration as highas50μg mL-1, and the result was given by the MTT viability assay. Furthermore,the DNA, RNA electrophoretic assay treated with DPA-TSB nanoparticles showsthe endotoxicity to the nucleic acid. These results above might be one of thereasons, which leads to the low cytotoxicity of bare nanoparitcle. It proved thatwater-dispersed nanoparticles fabricated by improved reprecipitation method can beuse for optical imaging agents. The significance of the promotion and developmentof this concept is that it can be chosen a suitable dye to synthesis a water-dispersednaoparticle and modified a necessary surface-bound folate moiety as targetbiomarker to apply for optical imaging or biosensing.The development direction of fluorescent materials in bioapplication wastargeted imaging. Therefore, we introduced the dual polarity copolymer which isusually in pharmaceutics formulation to the nano-prepare system to prepare a dyecoated with surfactants nanoparticle to realize the functionalization of nano-surfacein the subsequent researches. The advantages of the nanoparticles fabricated basedon the polarity copolymer with good biocompatibility are summarized as follows,on the one hand, it realizes the stable water dispersions of the hydrophobic dyes,and on the other hand, it provides the effective transmission of nanoparticle in vivo.Herein, in the paper we focous on the point that how to fabricate nanoparticle withhigh fluorescence by encapuslation dyes into micelle. We adopt a commercialamphiphilic copolymer CPEO20to prepare fluorescent micelles base on differentdyes and investigated the relationship between preparation parameter and fluorescence quantum yields. It can be synthesised fluorescent nano-micelle from anon-AIE molecues with high fluorescence efficiency (40%) via optimized synthesisparameters, which is higher that synthesis from AIE molecules. Based on thesemolecuelar configurations, it was found that molecules with high solid fluorescenceefficiency and small size changes of a molecule between excited sated and groundstates are in favor of fluorescent micelles with high fluorescence efficiency. It isexpanded the application of organic dyes in the bioimaging by the introduction ofamphiphilic copolymer and also can be realized multicolor display and targetedmark as well as disease treatment in vivo when modified specific functional groupon the surface.
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