Drug Delivery And Nanozyme Systems Based On Porous Materials

Porous materials contain netw ork structures which are resulted from closed or through holes.Because of their large specific surface area and low density,porous materials have been used in the fields of catalysis,optoelectronics,biomedicine,etc.This thesis has expanded on the basis of mesoporous silica materials,and completed the work of drug delvery and nanozyme systems.It is mainly divided into two aspects:(1)Exploring drug delivery systems based on mesoporous silica materialsp(a)We prepared ultrathin mesoporous silica layer coating on Mg-Al layered double hydroxide(LDH@MS)to improve the dispersibility and envirornmental stability of LDH and enhance the slow releasing capacity.It has been proved that the silica coating did not change the crystalline and structure of LDH,and actually improved the environment stability of LDH.It is found that this material was still sensitive to acidic conditions due to the decomposition of MS layer and the degradation of LDH core,so it could be used as a pH responsive nanocarrier of the drug delivery system.Curcumin was chosen as the model drug to evaluate the drug delivery concept of LDH@MS,and curcumin can be loaded in this system by two paths:1)the chelation between the diketone of curcumin and the metal anion ions of LDH,and 2)the physical adsorption between curcumin molecular and MS.This drug loaded nanosystem can slowly release curcumin until 144 h at the condition of pH-5.0,while parent LDH completed releasing within 2 h.Furthermore,this system showed 5-fold higher tumor cell killing efficiency(5.42 ?M)against MCF-7 than free curcumin(27.10 ?M),and the cellular uptake investigation exhibited numrous nanoparticles penetrated into cells within 2 h.We supposed that this nanosystem could be uptaken so quickly by cells that show high cell killing capacity.To explore the anti-tumor effect in vivo,murine liver tumor model(H22)was utilized.It is found that LDH@MS did not influence the body weight of mice and this nanosystem showed higher tumor inhibition(75%)than free curcumin(50%).All above illustrated that ultrathin mesoporous silica coating availably improved the environment stability and pH responsive drug release capacity,and enhanced the pharmaceutical efficiency of the model drug.(b)We chose Ni(OH)2 nanowires as the templet and etched Ni(OH)2 to prepare hollow mesoporous silica nanotubes(HMSNTs).SEM and TEM pictures showed that HMSNTs held the outside dimeter of around 60 run and the wall thickness of 20 nm.In order to improve the dispersibility of HMSNTs,-NH2 moiety was functionalized to the surface of the material,and adjusted the surface charge from-6.98 mV to 46.30 mV.BET characterization results showed that the surface area of HMSNTs was about 752.04 m2/g,and the diameter of the pores was 3-4 nm.The large surface area and measurable porous size are beneficial for the loading and release of the drug molecular.In order to evaluate the drug delivery function of HMSNTs,fluorescein and camptothecin were loaded into HMSNTs respectively,and the loading amounts were 21.8 and 18.9 wt%.For in vitro drug release,fluorescein was released about 70%within 300 min,while camptothecin was slowly released until 200 h.It is supposed that the water solubility of fluorescein was better than camptothecin,so the former was released quicker.HMSNTs showed no influence to cell viability at the concentration of 100 ?g/mL against MDA-MB-231 cells and camptothecin loaded in this nanosystem exhibited the same tumor cell killing efficiency as free camptothecin.In conclusion,this kind of material could be used as the nanocarrier for hydrophilic drug molecules.(2)P-RuSe2 with porous structure was prepared by using mesoporous silica KIT-6 as the template,and its peroxidase-like,oxidase-like and catalase-like activities were investigated.The experimental results showed that P-RuSe2 had a large specific surface area(131 m2/g)and a pore size distribution of about 6.12 nm.The XRD powder diffraction pattern exhibited a pyrite-type RuSe2 diffraction pattern.This material had better peroxidase-like,oxidase-like and catalase-like activities than Bulk-RuSe(B-RuSe2)prepared without using the template.In view of the excellent peroxidase-like activity of this material,it was explored for the detection of hydrogen peroxide and glucose.The linear range of detection was 0-1000 ?M and 0-250 ?M,respectively,and the detection limitations were both 5?M.