Chitosan / Pei / Silica Composite Nanoparticles Synthesized Dna Interactions With

Nanomaterial is a new cross-century material, which called " the most promising material in twenty-first Century ".In recent years, nanotechnology has become one of the world's attention advanced technologies, which is widely used in biology, aviation, military, electronics and other fields. Because of its promising clinical application, nano drug earring and DNA nano sensing technique become research hotspots.Nano drug carrier technology is such a technology that the nanometer carrier adsorbing or embedding drug come into living cells through cell phagocytosis, then controlled release of drugs. DNA nano sensing is a nanometer material as the sensitive element for DNA sensing.The main work of this paper is about the application of the nanoparticles as drug carrier for gene therapy and DNA biological nanosensor, combining the nanotechnology, nucleic acid techniques, fluorescence analysis technology. The main research contents can be classified as the following two parts:1. The synthesis of the chitosan/PEI/silica nanoparticles and the study of the drug loading capacityThe reverse microemulsion method was used for synthesize porous, good biological compatibility, surface aminated chitosan/PEI/silica nanoparticles. The particles diameter were about70nm. It owed uniform size, porous structure, and good dispersity. The nanoparticle surface shows electropositive in neutral physiological conditions from the zeta potential measured results. We studied the DNA adsorption characteristics and the intracellular transfection ability of the nanoparticles. The results showed that in the neutral physiological conditions, the nanoparticles owed high DNA separation and enrichment capabilities, and could be used for protect DNA from Dnase I cleavage. At the same time, it had good biological compatibility, whitch could entry into cells with normal cell growth activity. It owed the drug loading capacity. as the drug carrier, the P53tumor suppressor gene was effective transfected into murine leukemia cells, and killed the cancer cells through tumor suppressor gene expression.2. The study of the DNA biosensor designed by the fluorescein adsorbed chitosan/PEI/silica nanoparticles and its analytical applicationThe reverse microemulsion method was used for synthesize porous, good biological compatibility, surface aminated PEI/chitosan/silica nanoparticles. Due to PEI take positive charge in the neutral condition, fluorescein anionic and probe DNA (p-DNA)could adsorbed on the surface and hole through electrostatic interactions, then the DNA fluorescein-chitosan/PEI/silica nanosensor was formed. Based on the fluorescence quenching effect of the carbon nanotube (CNT) to fluorescein anion, the sensor was used for DNA hybridization sensing analysis. The experimental results showed that, the sensor had good sensing capabilities for different length DNA, and the detection limit was4.2×10-12M; at the same time, it could recognized the single base mismatch DNA. compared with dissociative fluorescein as the signal molecule, the sensor response signal was magnified4.36times. It was used for cell lysate, obvious signal response was found. It was a foundation for the research of using nano technology to the living cells, and provided a new way for signal amplification research with nanomaterial.