Preparation Of Organic Functionalized Hollow Silica Nanospheres And Their Application In Drug Delivery

Hollow silica nanospheres have shown great application potential in many fields because of their excellent properties,such as larger surface area,larger inner cavity,low toxicity,excellent biocompatibility and high stability.Organic functionalized hollow silica nanospheres with functional group modified in their framework can further broaden the applications of hollow silica,which have been widely applied in adsorption,drug delivery,catalysis,sensor,and environmental protection.In this paper,a facile and effective“functional group difference-based selective etching”strategy has been developed to prepare organic functionalized hollow silica nanospheres with highly monodisperse,well-defined morphology and uniform size.The key point of the strategy is to introduce different organic groups into both core and shell for purpose of changing their relative stability against etching,which results in the preferential etching of organic functionalized inner core.Here,our works mainly include two aspects:1.Synthesis of thiocyanato functionalized hollow silica nanospheres and their application in drug delivery.Organic bifunctionalized core-shell silica nanospheres,which are synthesized by using 2-cyanoethyltriethoxysilane（CTES）as core and3-thiocyanatopropyltriethoxysilane（TCPTES）as shell and ammonia hydroxide as catalyst,can be easily transformed to thiocyanato group functionalized hollow silica nanospheres（TC-HSNSs）in a Na₂CO₃ solution based on stability difference between the cyano group functionalized inner core and the thiocyanato group functionalized outer shell.In addition,the application of TC-HSNSs in drug delivery has also been investigated using aspirin as model drug.The structure and property of TC-HSNSs have been characterized by scanning electron microscopy（SEM）,transmission electron microscope（TEM）,energy dispersive spectroscopy（EDS）,elemental analysis（EA）,fourier transform infrared spectrometer（FT-IR）,automatic surface area and porosity analyzer（ASAP）and ultraviolet-visible spectrophotometer（UV-VIS）.The results shows that bifunctionalized core-shell silica nanospheres by hydrothermal treatment can be easily converted into TC-HSNSs with highly monodisperse,well defined morphology and uniform size in 0.01 g/mL Na₂CO₃solution at 50℃for 10 h.Additionally,TC-HSNSs show good performance of drug delivery for aspirin.The adsorption efficiency and release time of aspirin for TC-HSNSs reach at 14.6%and 24 h respectively,which are far more than that of pure solid silica and thiocyanato functionalized solid silica nanospheres.2.Synthesis of ureido functionalized hollow silica nanospheres and their application in drug delivery.Organic bifunctionalized core-shell silica nanospheres,which are synthesized by using 3-cyanopropyldichlorosilane（CPTES）as core and[3-（trimethoxysilyl）propyl]urea（UDPTMS）as shell and ammonia hydroxide as catalyst,can be easily transformed to ureido functionalized hollow silica nanospheres（UD-HSNSs）in a Na₂CO₃ solution based on stability difference between the cyano group functionalized inner core and the ureido group functionalized outer shell.In addition,the application of UD-HSNSs in drug delivery has also been investigated using aspirin as model drug.The structure and property of UD-HSNSs have been characterized by scanning electron microscopy（SEM）,transmission electron microscope（TEM）,fourier transform infrared spectrometer（FT-IR）,thermo gravimetric analyzer（TG）,automatic surface area porosity analyzer（ASAP）and ultraviolet-visible spectrophotometer（UV-VIS）.The results shows that bifunction-alized core-shell silica nanospheres by hydrothermal treatment can be easily converted into UD-HSNSs with highly monodisperse,well defined morphology and uniform size in 0.01 g/mL Na₂CO₃ solution at 50℃for 10 h.Additionally,UD-HSNSs show excellent performance of drug delivery for aspirin.The adsorption efficiency and release time of aspirin for UD-HSNSs reach at 20.1%and 26 h respectively,which are far more than that of ureido functionalized solid silica nanospheres.