Polyplex Particles Based on Comb-Like Polyethylenimine/Poly(2-ethyl-2-oxazoline) Copolymers: Relating Biological Performance with Morphology and Structure.

The present contribution is focused on feasibility of using comb-like copolymers of polyethylenimine with poly(2-ethyl-2-oxazoline) (LPEI-comb-PEtOx) with varying grafting densities and degrees of polymerization of PEI and PEtOx to deliver DNA molecules into cells. The copolymers form small and well-defined particles at elevated temperatures, which are used as platforms for binding and condensing DNA. The electrostatic interactions between particles and DNA result in formation of sub-100 nm polyplex particles of narrow size distribution and different morphology and structure.

Comblike Polyethylenimine-Based Polyplexes: Balancing Toxicity, Cell Internalization, and Transfection Efficiency via Polymer Chain Topology.

Comblike polyethylenimines with varying degrees of polymerization of both the main and side chains as well as different grafting densities were evaluated as gene delivery vectors. They were able to condense linear and plasmid DNA into nanosized polyplex particles with dimensions and surface potentials in the 130-330 nm and -30 to +15 mV ranges, respectively, depending on the amine/phosphate (N/P) ratio. The polyplexes remained stable in aqueous and buffer solutions from several hours up to several days.

Curcumin delivery from poly(acrylic acid-co-methyl methacrylate) hollow microparticles prevents dopamine-induced toxicity in rat brain synaptosomes.

The potential of poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) copolymers to form hollow particles and their further formulation as curcumin delivery system have been explored. The particles were functionalized by crosslinking the acrylic acid groups via bis-amide formation with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP) which simultaneously incorporated reversibility due to the presence of disulfide bonds within the crosslinker. Optical micrographs showed the formation of spherical hollow microparticles with a size ranging from 1 to 7 μm.

Poly(vinylamine) microgel-dextran composite hydrogels: characterisation; properties and pH-triggered degradation.

The present study involves an investigation of the formation, characterisation and triggered-degradation of mixed dispersions involving cationic poly(vinylamine-co-bis(ethyl vinylamine) ether) (PVAM-BEVAME) microgel (MG) particles and partially oxidised dextran (Dexox). In this approach to colloidal hydrogel composite formation, imine bonds were formed by reaction between aldehyde groups of Dexox and the primary amine groups on the MG particles. The composite hydrogels contained MG particles that were externally cross-linked by Dexox to form an elastically effective network with high storage modulus (G') values and low tanδ (=G″/G', where G″ is the loss modulus) values.

Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers.

pH-responsive physical gels from poly(meth)acrylic acid-containing crosslinked particles: the relationship between structure and mechanical properties.

Gels that feature high internal porosity and have both high elasticity and ductility have potential to provide immediate load support and enable subsequent tissue regeneration of damaged soft tissue if combined with cells. Herein, we report results from a recent investigation of novel poly(methyl methacrylate-co-methacrylic acid), (PMMA-MAA) and poly(ethyl acrylate-co-methacrylic acid), (PEA-MAA) biodegradable, pH-sensitive particle gels which are with high porosity, elasticity and ductility. These gels formed at physiological pH range and are potentially injectable.

Solution pH and oligoamine molecular weight dependence of the transition from monolayer to multilayer adsorption at the air-water interface from sodium dodecyl sulfate/oligoamine mixtures.

Neutron reflectivity and surface tension have been used to investigate the solution pH and oligoamine molecular weight dependence of the adsorption of sodium dodecyl sulfate (SDS)/oligoamine mixtures at the air-water interface. For diethylenetriamine, triamine, or triethylenetetramine, tetramine mixed with SDS, there is monolayer adsorption at pH 7 and 10, and multilayer adsorption at pH 3. For the slightly higher molecular weight tetraethylenepentamine, pentamine, and pentaethylenehexamine, hexamine, the adsorption is in the form of a monolayer at pH 3 and multilayers at pH 7 and 10.

Adsorption of the linear poly(ethyleneimine) precursor poly(2-ethyl-2-oxazoline) and sodium dodecyl sulfate mixtures at the air-water interface: the impact of modification of the poly(ethyleneimine) functionality.

The adsorption of the polymer-surfactant mixture of poly(2-ethyl-2-oxazoline)-sodium dodecyl sulfate at the air-water interface has been studied by neutron reflectivity and surface tension. The observed patterns of adsorption more closely resemble those encountered in weakly interacting polymer-surfactant mixtures, rather than the pronounced enhancements in adsorption observed in strongly interacting polymer-surfactant mixtures, such as in the related poly(ethyleneimine)-sodium dodecyl sulfate mixtures. The adsorption was found to be strongly dependent on solution pH, polymer molecular weight, and polymer concentration.

Effect of polymer molecular weight and solution pH on the surface properties of sodium dodecylsulfate-poly(ethyleneimine) mixtures.

The effect of polymer molecular weight and solution pH on the surface properties of the anionic surfactant sodium dodecylsulfate, SDS, and a range of small linear poly(ethyleneimine), PEI, polyelectrolytes of different molecular weights has been studied by surface tension, ST, and neutron reflectivity, NR, at the air-solution interface. The strong SDS-PEI interaction gives rise to a complex pattern of ST behavior which depends significantly on solution pH and PEI molecular weight. The ST data correlate broadly with the more direct determination of the surface adsorption and surface structure obtained using NR.

Effect of architecture on the formation of surface multilayer structures at the air-solution interface from mixtures of surfactant with small poly(ethyleneimine)s.

The impact of ethyleneimine architecture on the adsorption behavior of mixtures of small poly(ethyleneimines) and oligoethyleneimines (OEIs) with the anionic surfactant sodium dodecylsulfate (SDS) at the air-solution interface has been studied by surface tension (ST) and neutron reflectivity (NR). The strong surface interaction between OEI and SDS gives rise to complex surface tension behavior that has a pronounced pH dependence. The NR data provide more direct access to the surface structure and show that the patterns of ST behavior are correlated with substantial OEI/SDS adsorption and the spontaneous formation of surface multilayer structures.

Rheology of aqueous solutions of polyglycidol-based analogues to pluronic block copolymers.

The aqueous solution properties of a series of polyglycidol-poly(propylene oxide)-polyglycidol (PG-PPO-PG) block copolymers were investigated by means of rheology. The copolymers are considered as analogues to the commercially available Pluronic, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), block copolymers in which the flanking PEO blocks are substituted by blocks of structurally similar PG bearing a hydroxyl group in each repeating monomer unit. In the dilute regime, the samples normally behave as Newtonian fluids.

On the interrelationships between erythrocyte aggregation, plasma viscosity and the total peripheral resistance in arterial hypertension.

A probable conjunction of hemodynamic- and rheological variables was tested in hypertensive patients. Most pronounced correlation was fixed for some indices (sizable in value for plasma viscosity and small but distinct for blood pressure and ZSR) vs. total peripheral resistance.