Synthesis And Characterization Of Fluorescent Molecule Loaded Bimodal Mesoporous SiO₂ And Its Application In The Sustained Release Of Ibuprofen

As a drug carrier,mesoporous SiO₂ presents not only the high drug-loaded capacities but also the sustained drug-released performances.However,how to track or monitor the drug releasing behaviors in in-vivo system is one of main challenges.For this reason,many researchers focused on the grafting luminescent molecules into the mesoporous surface of silica-based matrix so as to assess the pharmacokinetic behavior of loaded drug by capturing its fluorescence signal.Along with the development of nanotechnology,various fluorescent molecular including different compositions,structures and fluorescence properties have been widely applied.These fluorescent molecules have their respective advantages accompanying some disadvantages,such as poor chemical stability,easy bleaching and low detection sensitivity of organic fluorescent molecules,limited rare earth material,poor water solubility and toxic side effects of quantum dots,which affect their application in drug delivery.Therefore,the fluorescent materials with good biocompatibility,stable and high fluorescent intensity,and low toxicity need to be explored for applicaiton in drug delivery in future.The research focus on improving the fluorescence intensity,luminescence stability and drug delivery performance of drug carriers by doping fluorescence molecular with wide source and low toxicity into the mesoporous BMMs using one-step sol-gel method.Meanwhile,various characterizations were employed to characterize their morphology,structural and luminescence property.Furthermore,the drug loading and release performance was explored by using ibuprofen(IBU)as a model drug.Meanwhile,the influence of species and doping amounts of fluorescent,preparation conditions to structure,fluorescence performance and drug delivery were investigated.Finally,the luminescence mechanism of fluorescence hybrid materials was elucidated.The stability of one-step sol-gel method have been checked.In addition,the effect of the size and doping amounts of fluorescent molecules on the hybrid materials using density nano-silica spheres(DNSS)as carrier and the detection performance of carbon quantum dots(CQDS)for heavy metal ions were studied.The main contents of this dissertation are as follows:(1)A new fluorescent hybrid material was prepared by introducing the luminescent molecules(perylene-3.4.9.10-tetracarboxylic-dianhydride(PTD)or4-amino-1,8-naphthalic anhydride(ANA)on the surface of3-aminopropyltriethoxysilane(APTES)-modified DNSS.The influence of fluorescent molecules size and doping amounts on structure and luminescent properties of the hybrid material,as well as the relationship between the surface fractal characteristics and the surface properties of the material were investigated.The results showed that the XRD patterns and N₂ adsorption/desorption isotherms of the materials remained unchanged before and after the grafting of fluorescent molecules of different doping amounts,indicating homogeneous dispersion of ANA or PTD on outer surface of APTES-modified DNSS and weakly influence to carrier structure.In addition,along with doping amount of fluorescence molecular increasing,the fluorescence intensity of ANA-DNSS improved with emission red shifting from 504 nm to 520 nm,while emission peak intensity of PTD-DNSS decreased with constant emission center at 525nm and 560 nm,which indicated doping amounts changing luminescence performance and state of fluorescent molecules.(2)The fluorescence hybrid materials(ZnO@BMMs,In₂O₃@BMMs)was prepared by a simple and reliable one-step synthesis route using metal oxides(ZnO,In₂O₃)as fluorescent molecules.The influence of raw material species,doping amounts,calcination condition on structure,properties,fluorescence property of hybrid material were investigated.Corresponding luminescence mechanism was elucidated.Furthermore,their drug delivery performance been assessed by using IBU as model drug.The results show that both ZnO@BMMs and In₂O₃@BMMs presented spherical particles,ordered bimodal mesoporous structure,excellent luminescent properties and large specific surface area for 948 m²/g and 1195 m²/g,respectively.With the doping amount of fluorescence molecular increasing,the specific surface area decreased,particle size increased and fluorescence intensity changed.Unlike post grafting method,one-step method influented structure and fluorescence property.Overmore,the fluorescence profiles of ZnO@BMMs and In₂O₃@BMMs exhibited ultraviolet emission of near band edge and blue-green fluorescence of oxygen defect.Both ZnO@BMMs and In₂O₃@BMMs presented rapid drug loading performance with high drug loading amounts(250 mg/g for ZnO@BMMs,177 mg/g for In₂O₃@BMMs),which was related to bimodal mesoporous structure.The fluorescence intensity of ZnO@BMMs and In₂O₃@BMMs decreased in drug release.(3)In order to further improve fluorescence stability,a multifunctional mesoporous CQDs/BMMs was synthesized for application in sustained IBU releasing.In which,the preparation method of CQDs was optimized and the influences of removing cetyltrimethyl ammonium bromide(CTAB)conditions(ethanol-HCl,isopropanol-H₂O,and acetone)on fluorescence performances and structure properties were investigated.The result showed that CQDs with excitation-independent emission properties had the strongest fluorescence via hydrothermal process of 0.2 mg/m L of glucose/water solution at 180°C for 20 h.The excitation-independent emission property was ascribed to particle size or/and confinement effect.On the orther hand,the isopropanol-water was optimum to remove CTAB.The resultant CQDs/BMMs possesses uniform mesopore structure with larger specific surface area of around 752m²/g,and excitation-independent emission properties at the strongest emission peak of488 nm.Compared with CQDs,the emisiong peak of CQDs/BMMs was red shifted that attributed to fluorescent molecular aggregation.Furthermore,CQDs/BMMs showed good sustained release performance along with more stable fluorescence than ZnO@BMMs and In₂O₃@BMMs.Moreover,the reliability and potential replication of one-step sol-gel method to synthesize similar materials have been verified via the successfully preparation of ZnO@BMMs,In₂O₃@BMMs and CQDs/BMMs.(4)The surface properties,fluorescence stability,the detection performance of heavy metal ions and quenching mechanism of CQDS were investigated in detail.The characterization of FT-IR and XPS showed CQDs with carboxyl,alkyl group and aryl functional group.The fluorescence intensity remained stable in high salt environment and p H 3-11.5 that implied the potential application of CQDs in detection heavy metal ions of complex systems.Specially,the detection of CQDs to Cr⁶⁺had short response time(<3 min)and low detection limit(0.05?M).Beside the UV spectrum and fluorescence lifetime of CQDs could been changed by Cr⁶⁺that indicated the quenching including dynamic and static effect.