Preparation And Smart Drug Delivery Property Of Gold Nanorods/Mesoporous Silica/Hydroxyapatite Hybrid Nanoparticles

In this paper,gold nanorod/mesoporous silica/hydroxyapatite?GNR/mSiO₂/HAP?hybrid nanoparticles with a GNR core and mSiO₂/HAP shell for multi-responsive drug delivery have been prepared.The prepared carrier possesses NIR-responsiveness and pH-responsiveness and biodegradability because of the introduction of HAP.In addition,the introduction of HAP alters the mesoporous structure of the original mesoporous silica shell,resulting in the relatively higher drug loading capability of GNR/mSiO₂/HAP compared with GNR/mSiO₂?GNR coated with mesoporous silica shell?.The studied drug carrier provides a novel method for silicon-based drug carrier with multi-responsiveness,high drug loading ability and good biodegradability.There are three major sections in this paper:Firstly,GNR/mSiO₂/HAP had been prepared with a GNR core.The effects of Na₂HPO4 concentration and reaction temperature on the growth of GNR/mSiO₂/HAP were investigated.TEM,XRD,and XPS analyses demonstrated that 5 mmol/L was the suitable concentration of Na₂HPO4 for the preparation of mSiO₂/HAP shells.GNR/mSiO₂/HAP prepared at 70°C?GNR/mSiO₂/HAP-70°C?had a higher HAP proportion than that prepared at 40°C?GNR/mSiO₂/HAP-40°C?,which demonstrated the higher reaction temperature could facilitate the formation of HAP in the inorganic hybrid shell.Secondly,the loading and release performance experiments of doxorubicin?DOX?were performed on GNR/mSiO₂/HAP-70°C and GNR/mSiO₂/HAP-40°C.The results demonstrated that GNR/mSi O₂/HAP had relatively high specific surface area?142.4 m2/g?and drug loading capacity.The drug loading efficiency of GNR/mSiO₂/HAP-70°C was 98.8%,compared with 86.7% for GNR/mSiO₂/HAP-40°C.In addition,GNR/mSiO₂/HAP had pH and NIR dual responsiveness.The degradation of HAP within inorganic hybrid shell under acidic condition and the local overheating effect of GNR could accelerate the drug release of GNR/mSiO₂/HAP.Therefore the drug release of GNR/mSiO₂/HAP at pH 4.5 and with NIR irradiation was as high as 37.6% within 12 h.The degradation experiments also showed that GNR/mSiO₂/HAP had good degradability,and the mSiO₂/HAP shell could be completely crushed within 24 h at pH 4.5 for the sake of the HAP degradation within inorganic hybrid shell under acidic condition.Cytotoxicity tests demonstrate the good biocompatibility of GNR/mSiO₂/HAP.Finally,the preparation conditions of GNR coating with pure HAP?GNR/HAP?had been investigated preliminarily.The effects of Na₂HPO4 concentration on the growth of GNR/HAP were explored.The results revealed that 1 mmol/L was the suitable concentration of Na₂HPO4 for the preparation of GNR/HAP.TEM and FTIR analyses also demonstrated the successful formation of HAP coated GNR structure.