Jeffamine M-1000 Research Articles

Double modular modification of thiolactone-containing polymers: towards polythiols and derived structures

A conceptual proof for the double modification (aminolysis and subsequent thiol-click modification) of thiolactone units, incorporated in linear polymer scaffolds, was elaborated. These polymers were prepared by either reversible addition–fragmentation chain transfer (RAFT) or nitroxide mediated radical polymerization (NMP) starting from a stable, readily available styrenic thiolactone monomer (St-TLa). Successful copolymerization of the latter with styrene (St) or methyl methacrylate (MMA) yielded linear polymers with varying thiolactone content (4–25%). Upon amine treatment, the ring-opening of the pendent thiolactones resulted in the formation of linear polythiols. Reaction conditions were optimized to avoid cross-linking via disulfide formation, thus preserving the linear nature of the polymer. Different primary amines (propylamine, benzylamine, ethanolamine and Jeffamine M-1000) were attached to the polymer backbone, while the PDIs remained low. The resulting polythiols are versatile scaffolds for further modification by various thiol-click reactions. In this respect, thiol–maleimide conjugation was used as a model reaction. NMR- and SEC-analyses revealed a near-quantitative double modification of thiolactone containing polystyrene (PS) and poly(methylmethacrylate) (PMMA) by subsequent treatment with propylamine and N-benzylmaleimide.

General route to graphene with liquid-like behavior by non-covalent modification

A graphene material with liquid-like behavior has been synthesized by decorating graphene in a generic, non-covalent fashion and subsequently combining the modified material with bulky polymer chains. The independently dispersed graphene core was first prepared through the chemical reduction of graphene oxide using a fluorescent whitening agent, VBL, as a non-covalent modifier. The negative groups of VBL, which are anchored onto the graphene sheets, impart anionic characteristics to graphene. The combination of the modified graphene with bulky Jeffamine M2070 chains through an electrostatic interaction yields a homogeneous graphene fluid, i.e., graphene-based nanoparticle ionic materials (G-NIMs). The microstructures of G-NIMs were characterized. G-NIMs can be stably dispersed in a broad spectrum of solvents with a super-high concentration of 500 mg mL−1. The intriguing properties of the graphene core and fluidity properties of G-NIMs may offer new scientific and technological opportunities for the applications of graphene.

CO2 Capture Capacity and Swelling Measurements of Liquid-like Nanoparticle Organic Hybrid Materials via Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

Novel nanoparticle organic hybrid materials (NOHMs), which are comprised of organic oligomers or polymers tethered to an inorganic nanosized cores of various sizes, have been synthesized, and their solvating property for CO2 was investigated using attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. Simultaneous measurements of CO2 capture capacity and swelling behaviors of polyetheramine (Jeffamine M-2070) and its corresponding NOHMs (NOHM-I-PE2070) were reported at temperatures of (298, 308, 323 and 353) K and CO2 pressure conditions ranging from (0 to 5.5) MPa. The polymeric canopy, or polymer bound to the nanoparticle surface, showed significantly less swelling behavior with enhanced or comparable CO2 capture capacity compared to pure unbound polyetheramine.

Guanidinylated Polyethyleneimine−Polyoxypropylene−Polyoxyethylene Conjugates as Gene Transfection Agents

Conjugates of linear and branched polyethyleneimine (PEI) and monoamine polyether Jeffamine M-2070 (PO/EO mol ratio 10/31, 2000 Da) were synthesized through polyether activation by cyanuric chloride followed by attachment to PEI and guanidinylation by 1H-pyrazole-carboxamidine hydrochloride. The resulting guanidinylated PEI-polyether conjugates (termed gPEI-Jeffamine) efficiently complexed plasmid DNA, and their polyplexes possessed enhanced colloidal stability in the presence of serum proteins. In vitro studies with mammalian CHO-1, 3T3, and Cos-7 cell lines demonstrated improved transfection efficiency of the pCMVbeta-gal plasmid/gPEI-Jeffamine polyplexes. The guanidinylation of the amino groups of PEI and the conjugation of PEI with the Jeffamine polyether enhanced the conjugates' interaction with genetic material and reduced the cytotoxicity of the polyplexes in experiments with the L929 cell line.

The Preparation of Colloidally Stable, Water-Soluble, Biocompatible, Semiconductor Nanocrystals with a Small Hydrodynamic Diameter

We report a simple, economical method for generating water-soluble, biocompatible nanocrystals that are colloidally robust and have a small hydrodynamic diameter. The nanocrystal phase transfer technique utilizes a low molecular weight amphiphilic polymer that is formed via maleic anhydride coupling of poly(styrene-co-maleic anhydride) with either ethanolamine or Jeffamine M-1000 polyetheramine. The polymer encapsulated water-soluble nanocrystals exhibit the same optical spectra as those formed initially in organic solvents, preserve photoluminescence intensities, are colloidally stable over a wide pH range (pH 3-13), have a small hydrodynamic diameter, and exhibit low levels of nonspecific binding to cells.

Modulation of cell membrane disruption by pH-responsive pseudo-peptides through grafting with hydrophilic side chains

The effect of grafting an amphiphilic pseudo-peptide, poly ( l-lysine iso-phthalamide), with poly (ethylene glycol) or a hydrophilic poly (ethylene glycol) analogue, Jeffamine M-1000®, on the pH-dependent erythrolytic activity and in vitro cytotoxicity have been studied together with the concentration-dependent haemolysis of the polymers with different degrees of grafting. PEGylated polymers showed pH-dependent membrane-disruptive ability similar to the parent poly ( l-lysine iso-phthalamide). The polymers showed a better ability to haemolyse the erythrocyte membrane at mildly acidic pHs with increasing degree of PEGylation (up to 17.0 wt.%). Further increasing the degree of PEGylation resulted in a decrease in haemolytic ability. Grafting poly ( l-lysine iso-phthalamide) with the lower molecular weight Jeffamine M-1000® had little effect on the haemolytic ability. Finally, the in vitro cytotoxicity of the grafted polymers was assessed by MTT assay, LDH assay and viable cell counts. At pH 7.4, these polymers were well tolerated by a range of mammalian cell lines and grafting reduced the cytotoxicity of polymers. However, at pH 5.5, relative to poly ( l-lysine iso-phthalamide), the grafted polymers displayed a better ability to rupture the outer membranes of these cells.

Modulation of the pH-responsive properties of poly( l-lysine iso-phthalamide) grafted with a poly(ethylene glycol) analogue

A pH responsive pseudopeptide, poly( l-lysine iso-phthalamide), has been modified with a hydrophilic poly(ethylene glycol) analogue, Jeffamine M-1000 ® and the effect of grafting ratio on the pH responsive behaviour of the grafted polymers in aqueous solution investigated using fluorescence and 1H NMR spectroscopy. It was demonstrated that at below 35.1 wt% grafting, the modified polymers retained the pH-driven conformational transition of the parent polymer from an expanded structure at high degrees of ionisation to a compact hydrophobically stabilised structure at low degrees of ionisation. The onset of pH response and the pH range over which the conformational transition occurred varied significantly with degree of grafting. At Jeffamine M-1000 ® ratios in excess of 48.0 wt%, the graft polymer existed in a micellular form over the whole pH studied. Potential applications in drug delivery of both the linear and micellular forms are discussed.