Thermo-, and pH dual-responsive poly(N-vinylimidazole): Preparation, characterization and its switchable catalytic activity

Comparing the transfection efficiency of cationic monomer ratios in vinylimidazole and aminoethyl methacrylate copolymers

Employing polycations as non-viral gene delivery vectors has been extensively studied owing to their safety, efficiency and possibility of modifying them in an intended way compared with viral vectors. However, the main challenge is finding a biocompatible and transfection-efficient polymer. In this study, 2-aminoethyl methacrylate (A) and 1-vinyl imidazole (V) were copolymerized at three different molar ratios by a free radical polymerization method and novel biocompatible polycations with narrow molecular weight distribution were obtained. The resulting copolymers were used for condensation of plasmid DNA (pDNA) at different N/P ratios followed by physicochemical characterizations of resulting polyplexes. At N/P ratio of 2, the nanoplexes were smaller than 120 nm. The optimum formulations were stable in presence of polyanions and capable of protecting the condensed pDNA against nucleases. The polyplexes having V to A molar ratio of 1:1 were the most efficient carrier in transfecting HeLa cells and were introduced as a promising non-viral vector.

Co-delivery of dasatinib and miR-30a by liposomes targeting neuropilin-1 receptors for triple-negative breast cancer therapy

Combinational therapy to treat triple-negative breast cancer (TNBC) by concomitantly influencing different cellular pathways has attracted attention recently. In the present study, co-delivery of dasatinib and miR30a by means of CRGDK-targeted lipopolyplexes was conducted to enhance the inhibition of cell proliferation and migration. For this purpose, we condensed the cationic copolymer poly(1-vinylimidazole-co-2-aminoethyl methacrylate) with miR-30a to form polyplexes. Next, the polyplexes and dasatinib were loaded in targeted liposomes via a thin-film hydration method to form final lipopolyplexes. Physicochemical properties of the nano-carriers were evaluated, and their influence on cellular uptake, cytotoxicity, cell migration, apoptosis induction, and Notch-1 mRNA levels as well as their transfection efficiency were assessed in the MDA-MB-231 cell line. Targeted dasatinib-loaded lipopolyplexes exhibited superior cell proliferation and migration inhibition and cellular uptake than dasatinib, polyplexes and non-targeted lipopolyplexes. Moreover, in comparison with non-targeted lipopolyplexes and polyplexes, targeted lipopolyplexes significantly transfected MDA-MB-231 cells and downregulated Notch-1 mRNA.

Novel ABA block copolymers: preparation, temperature sensitivity, and drug release

A new PEGylated macroiniferter was prepared based on the polycondensation reaction of polyethylene oxide (PEO), methylene diphenyl diisocyanate (MDI), and 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED). The macroiniferter consists of PEO end groups and readily reacts with acrylamides (such as N-isopropylacrylamide, NIPAM) and forms ABA block copolymers (PEO-PNIPAM-PEO). This approach of making amphiphilic ABA block copolymers is robust, versatile, and useful, particularly for the development of polymers for biomedical applications. The resulting amphiphilic PEO-PNIPAM-PEO block copolymers are also temperature sensitive, and their phase transition temperatures are close to human body temperature and therefore they have been applied as drug carriers for cancer treatment. Two PEO-PNIPAM-PEO polymers with different molecular weights were prepared and selected to make temperature-sensitive micelles. As a result of the biocompatibility of these micelles, cell viability tests proved that these micelles have low toxicity toward cancer cells. The resultant polymer micelles were then used as drug carriers to deliver the hydrophobic anticancer drug doxorubicin (DOX), and the results showed that they exhibit significantly higher cumulative drug release efficiency at higher temperatures. Moreover, after loading DOX into the micelles, cellular uptake experiments showed easy uptake and cell viability tests showed that DOX-loaded micelles possess a better therapeutic effect than free DOX at the same dose.

Upper Critical Solution Temperature Behavior of pH-Responsive Amphoteric Statistical Copolymers in Aqueous Solutions

Amphoteric statistical equivalent copolymers (P(2VP/NaSS) n ) composed of 2-vinylpyridine (2VP) and anionic sodium p-styrenesulfonate (NaSS) were prepared via reversible addition-fragmentation chain transfer polymerization. The degrees of polymerization (n) were 19 and 95. The monomer reactivity ratio, time conversion profile, and 1H nuclear magnetic resonance diffusion-ordered spectra suggested that the copolymerization of 2VP and NaSS provided statistical or near to random copolymers. P(2VP/NaSS) n exhibited an upper critical solution temperature (UCST) in acidic aqueous solutions on the basis of the charge interactions between the protonated cationic 2VP and anionic NaSS units. With an increase in pH value, the interaction was weakened because of the deprotonation of the 2VP units, thus reducing the UCST. At high [NaCl], the electrostatic interactions among the polymers were weakened because of the screening effect, and again, the UCST was reduced. With an increase in polymer concentration, the intra- and interpolymer interactions increased because of some entanglement, and the UCST consequently increased. Electrostatic interactions among the polymer chains with high molecular weight occurred easier than those among the low-molecular-weight polymer chains, which increased the UCST. The UCST also increased when deuterium oxide was used instead of hydrogen oxide, which was due to the isotopic effect. Hence, the UCST of P(2VP/NaSS) n can be adjusted according to the desired application.

A molecular level study of the phase transition process of hydrogen-bonding UCST polymers

A molecular level study of the UCST-type transition process of PNAGA-based polymers in water and a water/methanol mixture.

Stimuli-responsive hyperbranched poly(amidoamine)s integrated with thermal and pH sensitivity, reducible degradability and intrinsic photoluminescence

Stimuli-responsive HPA-C4s integrated with thermal and pH sensitivity, reducible degradability and intrinsic photoluminescence were successfully prepared and characterized.

pH-Responsive polymers

This review summarizes pH-responsive monomers, polymers and their derivative nano- and micro-structures including micelles, cross-linked micelles, microgels and hydrogels.

A biocompatible poly(N-vinylimidazole)-dot with both strong luminescence and good catalytic activity

A PVIm-dot was prepared through a simple hydrothermal method using PVIm as a sole carbon source without additives, which had both luminescence property and good catalytic activity.

Multi-Stimuli-Responsive Polymeric Materials

Stimuli-responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi-stimuli-responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi-stimuli-responsive character of these polymers, which are still relatively little known compared to their single-stimuli-responsive counterpart.