Multi-functional Drug-Loaded Microsphere Base On Fluorescent Quantum Dots/Dold Nanorods/Mesoporous Silica

Drug controlled delivery system take advantages of good treatment effect, less drug dosage and reduced side effects so that it has become a tendency of modern pharmacy development. Currently, multi-functional nanocomposite drug-loading system is more and more attractive for reseachers. For example, due to their special optical property, gold nanorods(GNRs) are wildly applied in the field of biomedicine,including biological imaging, biological monitoring, and photo-thermal therapy. Quantum dots are ordinarily used as fluorescent probes and biomarkers because of their strong fluorescence. Mesoporous silica is of enormous application potentiality as drug-loading materials. The multi-functional drug controlled delivery system combined a variety of functions to realize multiple responses, which is prospective in drug delivery systems.This paper prepared GNRs@m Si O2-Cd Te composite microspheres,which were constructed with a GNR core and a mesoporous silica shell,and Cd Te quantum dots were connected to the mesoporous silica layer. At the same time, the drug-loading and drug-releasing propreties of the GNRs@m Si O2-Cd Te microsphere were investigated. The reseach was carried out as follows:1. GNRs were synthesized by seed growth method. Firstly, the gold seeds were prepared in the presence of Na BH4 as the reductant and CTAB as the surfactant. The effect of Na BH4 concentrations on the synthesis of gold nanoparticle was investigated. Secondly, GNRs with controllable aspect ratio were prepared by AA as the reductant under the guiding of Ag NO3. The effects of Ag NO3 and AA on the aspect ratio and morphology characteristics of GNRs were discussed. The results showed that the more the Na BH4 consumption, the higher the GNR concentrations. The GNR concentration reached maximal when the amount of Na BH4 was 1.3 m L. The GNR concentrations increased with the increase of Ag NO3. The GNR concentration reached maximal whenthe amount of Ag NO3 was 0.6 m L. In addition, the GNR concentrations reduced with the increase of AA. The GNR concentration reached maximal when the amount of AA was 0.1 m L. Under the optimized condition, the as-prepared GNRs were of smooth surfaces and uniform aspect ratios.2. Water-soluble Cd Te quantum dots were synthesized in aqueous phase. The effect of reaction times on the synthesis of Cd Te quantum dots was discussed. When the reaction times were 10 min, 30 min, 60 min,100 min, 150 min, 210 min and 280 min respectively, the corresponding emission wavelength of Cd Te quantum dots were 540 nm, 577 nm,594 nm, 613 nm, 626 nm, 641 nm and 662 nm. The products were characterized by fluorescence spectrometer and transmission electron microscopy. The results showed that the maximum emission wavelength of Cd Te red-shifted with the increasing of reaction time and particle sizes.The fluorescence color was changed from green to red. When the react time was 100 min, the as-prepared quantum dots was about 4 nm, which showed an excellent dispersibility and a uniform size distribution.3. GNRs@m Si O2-Cd Te composite microspheres were synthesised on the base of GNRs@m Si O2-SH core-shell particles. The effect of tetraethyl orthosilicate(TEOS) on GNRs@m Si O2-Cd Te composite microsphere was discussed. The microsphere size increased with the increasing of TEOS. The as-prepared GNRs@m Si O2-SH was of core-shell structure. GNRs were wrapped in mesoporous silica layer with highly ordered porous structure and uniform pore size distribution. The pore dimeter of mesoporous silica was 2.6 nm, and pore volume was0.87 cm3/g. The specific suface area was 1365 m2/g. The fluorescent quantum dot was connected with GNRs@m Si O2-SH by covalent bond and the fluorescence can be easily detected in the as-prepared GNRs@m Si O2-Cd Te composite microspheres. After connection of quantum dots, the pore dimeter of mesoporous silica layer decreased to1.8 nm. The pore volume was 0.02 cm3/g, and the specific superface area was 17.1 m2/g.4. The loading and releasing performance of IBU in GNRs@m Si O2-Cd Te composite microspheres were studied. The resultsshowed that the drug loading capacity increased accompanying the increase of loading time, and then decreased while the loading time reached 70 min. For loading temperature, the drug loading capacity increased at first and then decreased with the increase of loading temperature, and the optimized temperature was 35 °C. Similarly, The drug loading capacity increased with the increase of p H, which reached maximal when the p H was 7.4. While the p H increased continuously, the drug loading capacity decreased. Under the optimized condition, the maximal drug loading capacity could reach 31.54 mg/g. The results of drug releasing experiments showed that the drug releasing percentage reached maximal when the temperture was 37 °C and the p H was 7.4.When the releasing time was extended to 10 hours, the cumulative drug releasing percentage could reach 90%. In an acidic solution, the cumulative release percentage was about 60-80%. In a weak basic solution(p H is around 8), the IBU releasing percentage was a relative low value of 33%.