Poly[(amino acid ester)phosphazenes] as substrates for the controlled release of small molecules

Allcock, Harry R.; Pucher, Shawn R.; Scopelianos, Angelo G.

doi:10.1016/0142-9612(94)90205-4

Cited by 103 publications

(81 citation statements)

References 17 publications

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“…The synthetic flexibility of polyphosphazenes has led to the development of a wide variety of polymers with diverse physical, chemical and biological properties [10]. Among them, amino acid ester polyphosphazenes are known to be hydrolytically sensitive and degrade into non-toxic and neutral products [11][12][13][14]. Also the degradation rates can be modified by varying the nature and ratio of the side groups [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)

et al. 2008

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Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA 50 PhPh 50 ) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) were prepared using a mutual solvent approach. Three different solvents, methylene chloride (MC), chloroform (CF) and tetrahydrofuran (THF) were studied to investigate solvent effects on blend miscibility. Three different blends were then fabricated at various weight ratios namely 25:75 (BLEND25), 50:50 (BLEND50), and 75:25 (BLEND75) using THF as the mutual solvent. The miscibility of the blends was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Among these, BLEND25 was miscible while BLEND50 and BLEND75 were partially miscible. Furthermore, BLEND25 formed apatite layers on its surface as evidenced in a biomimetic study performed. These novel blends showed cell adhesion and proliferation comparable to PLAGA. However, the PNEA 50 PhPh 50 component in the blends was able to increase the phenotypic expression and mineralized matrix synthesis of the primary rat osteoblasts (PRO) in vitro. Blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA 50 PhPh 50 ) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) are promising biomaterials for a variety of musculoskeletal applications.

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Section: Introductionmentioning

confidence: 99%

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)

et al. 2008

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“…The main interest in using polyphosphazenes for conduits is related to their biocompatibility and to the possibility of their entrapping capability, which promotes axonal growth in the polymeric mesh that is released during wall degradation [1,19].…”

Section: Discussionmentioning

confidence: 99%

Guided regeneration with resorbable conduits in experimental peripheral nerve injuries

Aldini

Fini

Rocca

et al. 2000

International Orthopaedics

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Guided tissue regeneration is a new approach in the reconstructive surgery of peripheral nerves. Artificial conduits can be constructed from biodegradable polymers. Lactic/caproic acid copolymers and polyphospazenes are biocompatible materials with a slow resorption rate. Conduits made from either poly-[l-lactide-co-6-caprolatone] or poly-[bis-(ethylalanate)-phosphazene] were assessed for use as guides for nerve regeneration in experimental animals. Under general anesthesia and by using a microsurgery technique both sciatic nerves were exposed in 2 groups of 9 Wistar rats. On the right side, a 10 mm segment of the nerve was removed, and the defect was then repaired using a conduit. On the left side, the same defect was bridged using as an autograft the nerve segment, which had been removed from the right sciatic nerve. Histological and electron microscopy investigations were performed after 30, 90 and 180 days and showed the gradual degradation of both types of conduits without any evidence of local toxicity. The regeneration of the nerve fibers in the lumen was not significantly different from that shown by the autologous grafts. Likewise, no differences were found at 180 days in the functional recovery of the nerve (evoked muscle action potential). Both conduits were found to be effective for guided nerve regeneration. Poly-[l-lactide-co-6-caprolactone] tubes were easier to insert, while polyphosphazene conduits allowed the use of neurite-promoting factors.Résumé La régénération tissulaire guidée est une nouvelle perspective dans la reconstruction des nerfs péri-phériques. Des conduits artificiels peuvent être obtenus avec des polymères biodégradables. Nous avons évalué dans un modèle expérimental deux types de polymères le poly-[1-lactide-co-6-caprolactone] et le poly-[bis-(etilalanate)-phosphazene]. Cette expérimentation a été, conduite sous anesthésie générale au niveau du nerf sciatique de 9 rats Wistar, un segment de 10 mm de nerf a été réséqué et du côté droit la reconstruction a été faite en utilisant une polymère du côté gauche, la réparation a été faite avec une autogreffe avec le segment réséqué du cô-té opposé. Une étude histologique et par microscopie électronique a été faite à 30, 90 et 180 jours. Il n'y a pas eu de toxicité locale des conduits en polymère. La régé-nération des fibres nerveuses dans les deux types de conduits ne fut pas différente de celle observée avec les autogreffes. Les deux types de conduits peuvent être considérés comme efficaces pour guider la régénération nerveuse. Le tube en polycaprolactone est plus maniable alors que celui en polyphosphazene peut contenir des facteurs favorisant la croissance axonale.

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“…Polyphosphazenes with ethylene oxy side groups can be crosslinked with γ-rays to give hydrogels, which have been investigated as controlled drug release agents [181][182][183][184][185]. Polyphosphazenes with amino acid side chains are biodegradable and can be employed to aid the regeneration of bone tissue in vivo [186][187][188][189]. Polyphosphazenes with aryloxy side groups have also been studied as fire retardants and thermoplastics.…”

Section: Ring-opening Polymerization Of Phosphazenesmentioning

confidence: 99%

Ring-Opening Polymerization—An Introductory Review

Nuyken

Pask²

2013

Polymers

365

265

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We would like to dedicate this article to P. H. Plesch, a pioneer of cationic polymerization and a mentor and friend for many of those who are now at the forefront of this field of science. He passed away 5 March 2013 at the age of 95. We will miss him. Abstract: This short, introductory review covers the still rapidly growing and industrially important field of ring opening polymerization (ROP). The review is organized according to mechanism (radical ROP (RROP), cationic ROP (CROP), anionic ROP (AROP) and ring-opening metathesis polymerization (ROMP)) rather than monomer classes. Nevertheless, the different groups of cyclic monomers are considered (olefins, ethers, thioethers, amines, lactones, thiolactones, lactams, disulfides, anhydrides, carbonates, silicones, phosphazenes and phosphonites) and the mechanisms by which they can be polymerized involving a ring-opening polymerization. Literature up to 2012 has been considered but the citations selected refer to detailed reviews and key papers, describing not only the latest developments but also the evolution of the current state of the art.

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Poly[(amino acid ester)phosphazenes] as substrates for the controlled release of small molecules

Cited by 103 publications

References 17 publications

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)

Guided regeneration with resorbable conduits in experimental peripheral nerve injuries

Ring-Opening Polymerization—An Introductory Review

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