Preparation Of Monodisperse Mesoporous Silica Nanoparticles And Application In DNA Transfection

Mesoporous material have the advantages of highly ordered mesostructures,adjustable pore diameter, high surface areas, so they can be widely used inseparation, sorption, catalysis. Mesoporous materials have become the focus ofresearch for many experts and scholars. With the rapid development of scienceand technology, more and more researchers have paid their attentions to prepareand use nano-materials. Mesoporous silica nanoparticles are successfully used asthe gene therapy, magnetic resonance imaging, biosensors, drug controlledrelease.This thesis mainly describes two preparation methods of the mesoporoussilica nanoparticles and their application in DNA nanocarriers. First, themesoporous silica nanoparticles were synthesized using ammonia and ethanol asthe catalyst and co-solvent in dilute solution synthesis, respectively, and theprocess was performed under the room temperature condition. Second, aninnovative approach was established with combined gel-sol synthesis withhomogeneous deposition method. The product was prepared using urea ascatalyst, and the system was reacted under the refluxed condition. The productsprepared by the two methods were characterized by XRD diffraction, BETnitrogen adsorption, scanning electron microscopy, transmission electronmicroscopy. Furthermore, the influence factors to the size and pore structure ofproduct was investigated, such as reaction temperature, time, the amount of ureaand surfactant additive. Last, its application was studied in detail, the innersurface of the mesopore was modified by functional group using AEAPTS, theadsorption of DNA to the modified particles(N-MSNs) in vitro were researched, and then the cell uptake of N-MSNs with different size were investigated.The results showed that mesoporous silica particles with the size of500nm,orderly arrangement of the pore, uniform size were synthesized in dilute solution.While the product in our innovative method had strong XRD diffraction peak,ordered mesostructure, good dispersion and uniform sphere, the size of theparticle was adjusted in the range of250nm to120nm, surface areas of795.3m~2/g, pore volume of0.55cm~3/g, average pore sizes of2.8nm. At last, the bestreaction condition was obtained by means of investigating the factors of reactiontime, temperature, the amount of urea and surfactant additive.The results of the adsorption of DNA to the N-MSNs indicated that smallsize N-MSNs had the ability to load the largest quantities of DNA, and a largenumber of20bp DNA were adsorbed by N-MSNs. The experimental result ofthe cell uptake of three different size of mesoporous silica showed that small sizeN-MSNs could be devoured by up to90%cells. The above-mentioned resultsproved that the cell uptake of small size N-MSNs was high-efficiency. Itdemonstrated that the mesoporous silica nanoparticles could be used as a goodgene carrier, and applied well in the research of gene therapy on cancer cells.