Studies On Construction Of A Novel Inorganic Nanopartlcles-based Gene Vector And Its Biological Effects

Gene therapy, as a new revolutionary treatment for diseases, had achievedsignificant development and drawn more attention in past decades. The key problem forgene therapy was how to build a gene vector with excellent biocompatibility and highdelivery efficacy. Gold nanocages (AuNCs) with localized surface plasmon resonance(LSPR) could absorb the light in the near-infrared (NIR) region (700~1200nm), which isconverted into heat for photothermal cancer treatment. Considerable amino-groups onpolyethyleneimine (PEI) could combine genes with negative charges through electrostaticinteraction to achieve target gene delivery for disease treatment.In this study, silver nanocubes were synthesized and then etched by chloroauric acidto obtain AuNCs. A novel gene vector, AuNCs-PEI, was prepared through anchoringthiolated PEI on surface of AuNCs by Au-S bond, the delivery efficiency of which forplasmid DNA was preliminarily evaluated. The results were shown as follows:1. Synthesis and characterization of silver nanocubes and AuNCsThe monodisperse silver nanocubes with edge length of45nm and uniformmorphology were synthesized by optimizing sodium sulfide volume (3mM) and the flowrate of Argon gas. Meanwhile, AuNCs with LSPR position at810nm were obtained bycontrolling the volume of chloroauric acid (0.1mM).2. Studies on the delivery efficacy of constructed AuNCs-PEIGene vectors, marked as AuNCs-PEI(1.8) and AuNCs-PEI(10), were prepared byligand exchange between PVP outside AuNCs and thiolated PEI (1.8) and PEI(10),respectively. The AuNCs-PEI dispersion was irradiated by the laser at800nm,temperature of which increased, indicating that AuNCs-PEI had significant photothermaleffect. The results of gel retardation assays showed that DNA could be attached onAuNCs-PEI completely when the mass ratio of Au/DNA was higher than1:1. Thecytotoxicity results demonstrated that,for AuNCs-PEI(10), the cell viability of293T cellswas still high with85%when the Au/DNA mass ratio was15. Furthermore, the viability of293T cells treated with AuNCs-PEI(1.8) was almost comparable to the control groups, which indicated that AuNCs-PEI(1.8) and AuNCs-PEI(10) possessed excellentbiocompatibility. The results obtained by fluorescence inverted microscope and flowcytometry showed that, the delivery efficacy of AuNCs-PEI(10) was up to15%when theAu/DNA mass ratio was15, which indicated AuNCs-PEI (10) could transfect target geneseffectively. We concluded that AuNCs-PEI(10) had great potential in gene therapy to treatrelated diseases.In addition, the conductivity of silver nanocubes and nanospheres with the same sizewas compared to illustrate the potential application of metal nanoparticles with specialshapes in printed electronics, such as nanocubes, nanobars and nanowires and soon.The results showed that the conductivity of printed patterns using silver nanosphereswas higher than that of patterns by silver nanocubes. Moreover, due to the advantages offacile synthesis method and large-scale production, silver nanospheres were superior tosilver nanocubes, which may suggested that conductive paste prepared by silvernanocubes had little prospect in practical application.