An easy and cost-effective sol-gel procedure is described for the synthesis and co-modification of mesoporous silica nanoparticles (MSNs) with various metal ions and positive-charge inducing polymers including PEI and PEG, for the construction of a reliable gene delivery vehicle. All of the samples (denoted as PEI-MSN, M-MSN, PEI-M-MSN, and PEG-PEI-MSN, where, M= Fe2+, Fe3+, Co2+, Zn2+, Al3+), were unambiguously characterized by conventional techniques including FTIR, XRD, SEM, and BET. The adsorption capacity of siRNA was found to be more related to the zeta potential of the samples than their specific surface areas. The best adsorption result was obtained by using PEI-Fe(III)-MSN (48.8 µg of siRNA per mg of support). The release of siRNA from PEIFe(III)-MSN, was also good (91.5%), but a burst release profile was observed. Interestingly, when a layer of PEG was used as a co-modifier, a sustained release profile was achieved, and meanwhile, the released amount of siRNA was improved (93.2%). The whole combination showed noconsiderable cytotoxicity according to the MTT test. پرونده مقاله

In the use of G-quadruplex as DNAzyme, the background signal corresponding to Hemin is high.Therefore, it limits the application of DNAzyme. If carbon nanotubes are added to the system containing G-quadruplex and Hemin, this problem will be solved. However, the mechanism of the nanotube effect on DNAzyme is not known. In this work, molecular dynamics simulation was used to clarify this mechanism. The interaction between G-quadruplex and Hemin was simulated in the presence and absence of carbon nanotubes. The calculated distance between the center of mass ofG-quadruplex and Hemin during the simulation time shows that the nanotube increases the affinity of hemin to G-quadruplex. Also, the calculation of the conformational factor of the G-quadruplex residues shows that Hemin is bonded to the G-quadruplex from the top and side. The obtained results are in good agreement with the available experimental evidence. پرونده مقاله