The interaction of GSSG modified magnetic nanoparticles with SPC-A1 cells in vitro

Magnetic nanoparticles(MNPs) are promising materials for various biomedical applications,including magnetic resonance imaging,stem cell tracking,gene/drug delivery,and cancer treatment.To increase the effectiveness of MNPs,high capture efficiency and controlled uptake of the particles by cells is required.In this paper we report the cytotoxicity and cellular uptake into SPC-A1 cells of oxidized glutathione(GSSG)-modified MNPs(GSSG@Fe3O4).Experimental findings indicated that GSSG@Fe3O4 were biocompatible,and could be efficiently taken up by SPC-A1 cells(up to 160 pg iron per cell).The internalized GSSG@Fe3O4 was retained in the cell cytoplasm for 6 generations.The uptake of GSSG@Fe3O4 into SPC-A1 cells was energy-,concentration-and time-dependent.Pinocytosis may be involved in the internalization process of GSSG@Fe3O4 into SPC-A1 cells,but this mechanism remains to be elucidated.The controlled and efficient localization of GSSG@Fe3O4 into the cytosol and long intracellular retention provides theoretical and experimental insight into the biomedical applications for these molecules.

Enhancement of the efficiency of PEI/liposome transfection by magnetofectins formed via electrostatic self-assembly

One of the major challenges for successful gene therapy is improving the transfection efficiency of non-viral vectors. Magnetic nanoparticles (MNPs) have been developed as enhancers of non-viral vehicles. We prepared MNPs and modified them with polyethyleneimine (PEI), citric acid (CA) or carboxylmethyl-dextran (CMD). Both positively charged MNPs (MNPs@PEI) and negatively charged MNPs (MNPs@CA, MNPs@CMD) could spontaneously form transfection complexes (magnetofectins) with plasmid DNA and PEI/liposome via electrostatic self-assembly. Our results showed as-prepared magnetofectins apparently enhanced PEI/liposome transfection efficiency and/or gene expression level into COS-7 cells with reduced transfection time from 4 h to 15 min under a magnetic field in vitro. Meanwhile, the effect of magnetofection was cell line-dependant. These results suggest that charged MNPs could improve transfection efficiency for non-viral vectors by simply mixing with them and by exerting a magnetic force. Thus such MNPs provide a convenient platform for further applications of gene delivery.

Folic Acid Functionalized PFBT Fluorescent Polymer Dots for Tumor Imaging

Folic acid functionalized PFBT-COOH and PFBT-NH2 polymer dots were prepared using a nano precipitation method, and their applications for tumor imaging in vitro and in vivo were demonstrated for the first time. The syn- thesized FA-PFBT-COOH polymer dots were 50--60 nm in diameter with a zeta potential of greater than -30 mV in water, while the synthesized FA-PFBT-NH2 polymer dots were 90-- 105 nm in diameter with a zeta potential of greater than -20 mV in water. Furthermore, the FA-PFBT-COOH polymer dots produced stronger fluorescence in- tensity in water solution as well as in the cells than the FA-PFBT-NH2 polymer dots, and were able to image H1299 tumors in living mice after intravenous injection. This study showed the great potentials of FA-PFBT-COOH poly- mer dots as fluorescent nanoprobes for biomedical imaging.

Modeling of the fibrin agarose plate assay and its application for thrombolytic analysis

The fibrin agarose plate assay is widely used in the detection of thrombolysis efficacy. However, a rigorous mathematical model for analyzing data or comparing activities of different thrombolytics has been absent. This study investigated the relationship between thrombolysis radius, R, and diffusion time, t, of molecular medicines in an agarose hydrogel system by deriving a model based on Fick's law and experimental verification by the fibrin agarose plate assay method. The theoretical results showed that a plot of log(R) versus log(t) has a linear curve with the slope of 1/2 and this was verified by experimental results using urokinase as a modeling agent. Moreover, it was found that R÷t is constant for a specific thrombolytic and can be used as a parameter for evaluating activities of different thrombolytics. The theoretical model has potential for improving the understanding of mecha-nisms involved in molecular medicine diffusion and offers benefits for thrombolytic therapy.