Preparation And Application Of Fluorescent Silica Nanospheres Based On PH Response

In recent years,human health has been seriously threatened because of the intensified serious environmental pollution and food safety issues.New cases of cancer increased year by year,so that it has been urgent to develop effective detection methods and anti-cancer methods.With the development of nanotechnology,fluorescent nanomaterials have become increasingly prominent in the field of biomedicine.In order to meet the needs of medical technology,fluorescent nanomaterials are facing the trend of biocompatibility,fluorescent signal stability and efficiency,specificity and easy functional.In view of the important role of pH in the regulation of biological activity,and the occurrence of life phenomena closely related with the change of intracellular pH value,pH responsive fluorescent nanosilica spheres have stood out with many excellent performances.Since the pH response performance can not only come from the fluorescent dye itself,but also be obtained by pH response functional groups.Therefore,this paper prepared two different fluorescent nanosilica spheres,and initial studied its application in pH sensor and drug release.In this paper,fluorescent nanosilicon spheres were prepared by using isothiocyanide fluorescent dye as fluorescence source and silica with good biocompatibility and easy modification as carrier.Firstly,the classification,synthesis methods and potential applications of fluorescent nanoparticles and pH responsive materials were reviewed,and the significance of this study is expounded.Taking advantage of the feature of silane coupling agent ?-aminopropyltriethoxysilane(APTES)not only its amino can add isothiocyanide to form Schiff base,but also can hydrolysis condensation with TEOS,Fluorescein isothiocyanate(FITC)bonded fluorescent silica nanospheres were synthesized.According to the location of FITC in the microspheres,there are the two types of fluorescent silica spheres:covered type(c-FSNs)and surface connection type(s-FSNs).A comparative analysis of their performance found that: compared with s-FSNs,c-FSNs has low bleaching degree and good light stability.c-FSNs prepared by Reverse microemulsion method(W/O)has easy-controlled smaller particle size and higher fluorescence signal than St?ber method.Besides,c-FSNs prepared by W/O has a mesoporous structure,and has more conducive to the application of biomedical and other aspects.The study of c-FSNs as a pH sensor found that it responsed rapidly,the growth of fluorescence intensity was almost as a line in the pH of 5.2-7.8,and p Ka was about 6.32.It had good reversibility,reproducibility,accuracy and biological phase capacitive.Based on the characteristics of polyacrylic acid(PAA)with pH response,after Rhodamine thiocyanate(RITC)bonded fluorescent silica nanospheres were synthesized with fluorescent precursor of RITC-APTES,amination was modified in the surface to bond PAA,then,pH responsive mesopores fluorescent nanosilica spheres(PAA-FMSNs)were prepared.The results of characterization showed that the average particle size of the product is about 174 nm,the pore size is 16.6 nm and the specific surface area is 17.3 m2?g-1,which indicated that it has good dispersion and biocompatibility.Doxorubicin hydrochloride(DOX)was used as model drug to study the ability of PAA-FMSNs as pH-responsive nano-drug carrier.Results showed that when the DOX: PAA-FMSNs is 1.5,the entrapment efficiency(94.5%)and a drug loading(58.6%)of fluorescent nanosilica spheres carrier are higher,and with the decrease of pH in the range of pH from7.4 to 5.4,drug release rate was significantly increased,with significant pH response.