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Robert Langer - One of the best experts on this subject based on the ideXlab platform.

  • degradable poly β amino Esters synthesis characterization and self assembly with plasmid dna
    Journal of the American Chemical Society, 2000
    Co-Authors: Robert Langer
    Abstract:

    Poly(β-aminoEsters) 1−3 were synthesized via the addition of N,N‘-dimethylethylenediamine, piperazine, and 4,4‘-trimethylenedipiperidine to 1,4-butanediol diAcrylate. Polymerization proceeded exclusively via the conjugate addition of the secondary amines to the bis(Acrylate Ester). Polymers were isolated in up to 86% yields with molecular weights ranging up to 31 200 relative to polystyrene standards. The polymers degraded hydrolytically in acidic and alkaline media to yield 1,4-butanediol and β-amino acids 4a−6a and the degradation kinetics were investigated at pH 5.1 and 7.4. In general, the polymers degraded more rapidly at pH 7.4 than at pH 5.1. In initial screening assays, both the polymers and their degradation products were determined to be noncytotoxic relative to poly(ethylene imine), a polymer conventionally employed as a synthetic transfection vector. Polymers 1−3 interacted electrostatically with polyanionic plasmid DNA in water and buffer at physiological pH, as determined by agarose gel elec...

Bansi Lal - One of the best experts on this subject based on the ideXlab platform.

Arun K. Ghosh - One of the best experts on this subject based on the ideXlab platform.

E Wagner - One of the best experts on this subject based on the ideXlab platform.

  • Novel degradable oligoethylenimine Acrylate Ester-based pseudodendrimers for in vitro and in vivo gene transfer
    Gene Therapy, 2008
    Co-Authors: V Russ, H Elfberg, C Thoma, J Kloeckner, M Ogris, E Wagner
    Abstract:

    A novel class of cationic hyperbranched polymers, containing branched oligoethylenimine (OEI 800 Da) as core, diAcrylate Esters as linkers and oligoamines as surface modification, was synthesized and evaluated regarding their structure–activity relationship as gene carriers. We show that pseudodendritic core characteristics as well as different surface modifications on the core influence DNA-binding ability, cytotoxicity and transfection efficiency. As most promising gene carrier, the pseudodendrimer HD O, that is, the OEI 800 Da core modified with hexane-1,6-diol diAcrylate and surface-modified with OEI 800 Da, was identified. HD O exhibits efficient DNA-condensing ability to nanosized polyplexes (100–200 nm), low cytotoxicity, a degradation half-life of 3 days at 37 °C at physiological pH and in vitro reporter gene-expression levels similar to high molecular weight linear and branched polyethylenimines (PEIs) (LPEI and BPEI). In vivo studies in mice reveal that HD O/DNA polyplexes upon i.v. tail-vein injection have the potential for transfection of tumor tissue at levels comparable to that obtained with LPEI. Importantly, HD O was better tolerated than LPEI, while transgene expression was more tumor-specific and much lower in all other investigated organs, especially in the lung (15 000-fold lower compared with LPEI).

Deborah D.l. Chung - One of the best experts on this subject based on the ideXlab platform.

  • Piezoelectric behavior of three-dimensionally printed Acrylate polymer without filler or poling
    Journal of Materials Science, 2018
    Co-Authors: Patatri Chakraborty, Chi Zhou, Deborah D.l. Chung
    Abstract:

    We report the piezoelectric behavior of three-dimensionally layer-by-layer printed (bottom-up stereolithography, 21–46-µm layer thickness) polymer without filler or poling, using unmodified ultraviolet-curable resins (Acrylate Ester for Resin 1, and methAcrylated monomers/oligomers for Resin 2) that are not known to be piezoelectric. The smaller is the layer thickness, the greater is the shear stress in printing, the more is the molecular alignment, the higher is the out-of-plane electric permittivity, and the stronger is the out-of-plane direct piezoelectric effect, as shown by the electric field output decreasing reversibly and the capacitance increasing reversibly upon out-of-plane compression (stress ≥ 0.3 kPa). The piezoelectric effect is not merely due to the applied stress increasing the permittivity. The decrease in the electric field output is quite linear up to a stress of ~ 33 kPa. Decrease in the layer thickness from 46 to 26 µm increases the relative permittivity from 5.3 to 6.1 and increases the piezoelectric coupling coefficient d from 0.13 to 0.24 pC/N. Resin 2 gives a higher d than Resin 1 (0.43 vs. 0.24 pC/N), probably due to the higher viscosity and consequent higher shear stress during printing. The fractional change in capacitance due to the applied stress increases with decreasing layer thickness, is greater for Resin 2 than Resin 1, and increases with decreasing applied electric field, which causes a converse piezoelectric effect. The capacitance increases with increasing applied electric field used to measure the capacitance. The fractional change in capacitance due to the applied electric field decreases with increasing stress.