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Degradable Polymers (degradable + polymer)

Distribution by Scientific Domains

Polymers and Materials Science	71%

Selected Abstracts

Combinatorial Modification of Degradable Polymers Enables Transfection of Human Cells Comparable to Adenovirus,

ADVANCED MATERIALS, Issue 19 2007
J. Green
End-modified poly(,-amino ester)s, easy-to-synthesize degradable polymers, are able to deliver DNA to primary human cells at levels comparable to adenovirus and two orders of magnitude better than the commonly used non-viral vector, polyethylenimine. Small structural changes are found to affect multiple steps of gene delivery including the DNA binding affinity, nanoparticle size, intracellular DNA uptake, and final protein expression. In vivo, these polymer modifications enhance DNA delivery to ovarian tumors. [source]

A Delivery System for Self-Healing Inorganic Films,

ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008
Harvey A. Liu
Abstract Multilayer composites that utilize polymeric and brittle inorganic films are essential components for extending the lifetimes and exploiting the flexibility of many electronic devices. However, crack formation within the brittle inorganic layers that arise from defects as well as the flexing of these multilayer composite materials allows the influx of atmospheric water, a major source of device degradation. Thus, a composite material that can initiate self-healing upon the influx of environmental water through defects or stress-induced cracks would find potential applications in multilayer composite materials for permeation barriers. In the present study, the reactive metal oxide precursor TiCl4 is encapsulated within the pores of a degradable polymer, poly(lactic acid) (PLA). Electrospun PLA fibers are found to be reactive to atmospheric water leading to the hydrolysis of the degradable polymer shell and subsequent release of the reactive metal oxide precursor. Release of the reactive TiCl4 from the pores results in hydrolysis of the metal oxide precursor, forming solid titanium oxides at the surface of the fibers. The efficacy of this self-healing delivery system is also demonstrated by the integration of these reactive fibers in the polymer planarization layer, poly(methyl methacrylate), of a multilayer film, upon which an alumina barrier layer is deposited. The introduction of nanocracks in the alumina barrier layer lead to the release of the metal oxide precursor from the pores of the fibers and the formation of titanium dioxide nanoparticles within the crack and upon the thin film surface. In this study the first delivery system that may find utility for the self-healing of multilayer barrier films through the site-specific delivery of metal oxide nanoparticles through smart reactive composite fibers is established. [source]

Combinatorial Modification of Degradable Polymers Enables Transfection of Human Cells Comparable to Adenovirus,

Repair of segmental defects in rabbit humeri with titanium fiber mesh cylinders containing recombinant human bone morphogenetic protein-2 (rhBMP-2) and a synthetic polymer

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002
Narumichi Murakami
Abstract To develop a new technology that enhances the regeneration potential of bone and the repair of large intercalated defects in long bone, recombinant human bone morphogenetic protein-2 (BMP-2; 20 ,g or 40 ,g) was mixed in a polymer gel (poly-lactic acid-polyethyleneglycol block copolymer; PLA-PEG; 200 mg) and incorporated into titanium fiber-mesh cylinders. Three 5-mm cylinders were placed end-to-end to fill a 15-mm defect created in the humeri of adult rabbits and were stabilized by an intramedullary rod. In controls, the titanium fiber-mesh cylinders were combined with PLA-PEG in the absence of BMP. Six weeks after implantation, new bone had formed on the surface of the implant and had bridged the defect. All of the defects (5/5) treated by cylinders containing 120 ,g (40 ,g × 3) of BMP were repaired completely. New bone formation was also found inside the pores of the cylinders. The defect was not repaired in the control animals. These results demonstrate that these new composite implants fabricated by combining rhBMP, synthetic degradable polymers and compatible biomaterials enhance the regeneration potential of bone. Thus, it is possible that large skeletal defects can be repaired using this prosthesis in lieu of autogenous bone graft. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 169,174, 2002 [source]

New strategies for polymer development in pharmaceutical science , a short review

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2001
A. Godwin
We are developing synthetic polymers for pharmaceutical and medical applications. These applications can be broadly grouped on how the polymer will be utilized e.g. material, excipient or molecule. Our focus is to develop polymers with more defined structures that are based on biological, physicochemical and/or materials criteria. Strategies are being developed to more efficiently optimize structure,property correlations during preclinical development. We describe two examples of our research on pharmaceutical polymer development: narrow molecular weight distribution (MWD) homopolymeric precursors which can be functionalized to give families of narrow MWD homo- and co-polymers, and hydrolytically degradable polymers. [source]

Synthesis of hyperbranched degradable polymers by atom transfer radical (Co)polymerization of inimers with ester or disulfide groups

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2009
Nicolay V. Tsarevsky
Abstract Degradable hyperbranched polymers with multiple alkyl halide chain ends were synthesized by the atom transfer radical polymerization of inimers containing ester (2-(2,-bromopropionyloxy)ethyl acrylate) or disulfide (2-(2,-bromoisobutyryloxy)ethyl 2,,-methacryloyloxyethyl disulfide) groups. Both the homo- and copolymerizations (with styrene in the former case and methyl methacrylate in the latter) were studied. The hyperbranched polymers derived from the ester-type inimer were hydrolytically degradable under basic conditions, whereas those derived from the disulfide-containing inimer could be efficiently degraded in the presence of reducing agents such as tributylphosphine. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009 [source]

Facile synthesis of functional polyperoxides by radical alternating copolymerization of 1,3-dienes with oxygen

THE CHEMICAL RECORD, Issue 5 2009
Eriko Sato
Abstract We have developed a facile synthesis of degradable polyperoxides by the radical alternating copolymerization of 1,3-diene monomers with molecular oxygen at an atmospheric pressure. In this review, the synthesis, the degradation behavior, and the applications of functional polyperoxides are summarized. The alkyl sorbates as the conjugated 1,3-dienes gave a regiospecific alternating copolymer by exclusive 5,4-addition during polymerization and the resulting polyperoxides decomposed by the homolysis of a peroxy linkage followed by successive , -scissions. The preference of 5,4-addition was well rationalized by theoretical calculations. The degradation of the polyperoxides occurred with various stimuli, such as heating, UV irradiation, a redox reaction with amines, and an enzyme reaction. The various functional polyperoxides were synthesized by following two methods, one is the direct copolymerization of functional 1,3-dienes, and the other is the functionalization of the precursor polyperoxides. Water soluble polyperoxides were also prepared, and the LCST behavior and the application to a drug carrier in the drug delivery system were investigated. In order to design various types of degradable polymers and gels we developed a method for the introduction of dienyl groups into the precursor polymers. The resulting dienyl-functionalized polymers were used for the degradable gels. The degradable branched copolymers showed a microphase-separated structure, which changed owing to the degradation of the polyperoxide segments. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000,000; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900009 [source]