Lyophilization of polycation/pDNA complexes provides stable, long‐term storage of complexes prior to clinical use but also reduces gene delivery efficiency. We examined whether polycation structure mediates effects of lyophilization on gene expression. Linear and branched PEI of the same molecular weight were used as a model system. Interestingly, pDNA/linear PEI complexes led to much smaller effects on gene expression following lyophilization compared with branched PEI complexes. The effect of polycation structure correlated with changes in dissociation ability of pDNA/PEI complexes. These results will be useful for developing new gene delivery vehicles.
Poly(vinyl alcohol)‐pyrene‐anti‐metadherin (PVA‐Py‐(Anti‐MTDH)), a novel antibody based water soluble probe containing both fluorescent and target sites in the structure for in vitro imaging of breast cancer cells is reported here. Since breast cancer cells have an excess of MDTH protein expressed on the surface, a PVA‐Py prepared by “Click chemistry” approach is targeted by Anti‐MTDH antibody and applied to the MCF‐7 cell line. After characterization, the designed architecture was evaluated in terms of cell incorporation efficiency and compared with a non‐targeted structure (PVA‐Py). Atomic force microscopy (AFM) and fluorescence microscopy images of cells after incubation of the probe molecules were also obtained to monitor the interaction of the probes with the cancerous cells.
DNA fibers were prepared by solution spinning of DNA in a lysozyme (LSZ) coagulation/gelation bath. Strong positive charges carried by LSZ protein condensed the DNA (strong negative charged) molecules resulting in self‐assembly and the formation of fibrillar structures in a gel‐like network. DNA/LSZ fibril formation was found to be dependent on the ratio of DNA to LSZ. A minimum 0.1 wt.‐% of LSZ was necessary to condense 0.1 wt.‐% of DNA into micro‐fibrils. Macroscopic fiber spinning was possible by introducing a 0.1 wt.‐% DNA aqueous solution into a 0.2 wt.‐% LSZ coagulation bath which resulted in fibers with ≈20 µm diameter. Single‐walled carbon nanotubes (SWNT) were also incorporated into these fibers to explore the possibility for creating hybrid materials. All DNA‐based fibers exhibit strong birefringence confirming molecular orientation along the fiber axis. Due to the presence of LSZ, the fibers exhibit antimicrobial activity against bacteria like Micrococcus lysodeikticus.
When lysozyme is dissolved in a neutral HEPES buffer solution (pH = 7.4) with 0.001–0.050 M TCEP added, a fast phase transition process occurs and the resulting novel fiber‐like hierarchical supramolecular assemblies made by primary spherical‐particle aggregation can function as a “superglue” that binds strongly and quickly onto non‐fouling coatings. This binding is highly selective towards lysozyme, and excludes synthetic, chemical/physical activation/deactivation (blocking) steps. By using biotinylated lysozyme, such a phase transition quickly creates a perfect biotinylated surface on non‐fouling surfaces for avidin binding, showing great potential for the development of low‐cost and practical biochips.
In this work, we present the preparation of water‐soluble poly(methacrylate)s with pendant cationic L ‐lysines PHMLs(6–30 K). Plasmid DNA binding affinity as well as particle sizes and zeta potentials of the polyplexes were examined for these PHML vectors, and their cytotoxicities were assayed with HeLa cells by CCK‐8 and lactate dehydrogenase kits. Gene transfection efficacy and intracellular uptake of the polyplexes by the PHML vectors were also studied with HeLa cells. As a result, it was revealed that the low cytotoxic PHMLs tended to exhibit gene transfection efficiencies significantly higher than those of the linear structural PLL (15–30 K) control, in particular the molecular weight of a PHML vector remarkably influenced its pDNA binding affinity, transfection efficacy and intracellular uptake of the polyplexes.
An experimental investigation of nonoxidative thermal degradation kinetics of nylon 66 melt under high temperature (280–300 °C) and low water content (0.02–0.14 wt.‐%) conditions is presented. Experimental data for the time evolution of polymer end‐group concentrations and degradation‐product generation rates were compared with the predictions of the only published kinetic model. The omitted influence of water content is a plausible partial explanation for the considerable discrepancy between model predictions and some data. Several previously unreported or unquantified degradation products were identified and measured. Potential additional reactions to account for these results in future kinetic models are proposed.
