Bioerodible polyphosphazenes and their medical potential

Allcock, Harry R.; Morozowich, Nicole L.

doi:10.1039/c1py00468a

Cited by 136 publications

(178 citation statements)

References 109 publications

(286 reference statements)

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“…1). Efficient control of temperature is important for complete polymerization since Cl cleavage is minimal at temperature far below 250°C [5, 10, 32, 39, 40, 44, 61]. Significant crosslinking may occur when 250°C is exceeded [10].…”

Section: Synthesis Of Polyphosphazene – Mechanisms Of Polymerizationmentioning

confidence: 99%

“…Incorporation of different side groups can alter the degradation rate and mechanical properties of the polymer [4, 9, 28, 32, 39-41]. For example, amino acid ester side groups will instigate hydrolysis within the polymer backbone [5, 9, 32, 40, 42] while there is a retardation of hydrolysis in the presence of hydrophobic phenylphenoxy side groups [4, 8, 15, 19, 43]. Unlike the polyester family, amino acid ethyl ester substituted polyphosphazenes undergo hydrolysis generating non-toxic and buffering degradation products composed mainly of phosphate, ammonia, and corresponding side groups [10, 23, 39, 44-47].…”

Section: Introductionmentioning

confidence: 99%

“…The pH profiles of the media in which these blends degraded were much higher than that of the PLAGA's as the polyphosphazene degradation products were able to neutralize the acidic degradation products from the PLAGA. However, majority of these blend systems do not possess requisite mechanical properties needed for bone tissue engineering [5, 9, 18, 19, 23, 29, 39, 41, 43, 46, 47, 50, 55]. It is still a lingering issue to fabricate completely miscible PPHOS-PLAGA blends with appropriate mechanical properties for bone tissue engineering applications.…”

Section: Introductionmentioning

confidence: 99%

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Biodegradable Polyphosphazene-Based Blends for Regenerative Engineering

Ogueri

Ivirico

Nair

et al. 2017

Regen. Eng. Transl. Med.

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The occurrence of musculoskeletal tissue injury or disease and the subsequent functional impairment is at an alarming rate. It continues to be one of the most challenging problems in the human health care. Regenerative engineering offers a promising transdisciplinary strategy for tissues regeneration based on the convergence of tissue engineering, advanced materials science, stem cell science, developmental biology and clinical translation. Biomaterials are emerging as extracellular-mimicking matrices designed to provide instructive cues to control cell behavior and ultimately, be applied as therapies to regenerate damaged tissues. Biodegradable polymers constitute an attractive class of biomaterials for the development of scaffolds due to their flexibility in chemistry and the ability to be excreted or resorbed by the body. Herein, the focus will be on biodegradable polyphosphazene-based blend systems. The synthetic flexibility of polyphosphazene, combined with the unique inorganic backbone, has provided a springboard for more research and subsequent development of numerous novel materials that are capable of forming miscible blends with poly (lactide-co-glycolide) (PLAGA). Laurencin and co-workers has demonstrated the exploitation of the synthetic flexibility of Polyphosphazene that will allow the design of novel polymers, which can form miscible blends with PLAGA for biomedical applications. These novel blends, due to their well-tuned biodegradability, and mechanical and biological properties coupled with the buffering capacity of the degradation products, constitute ideal materials for regeneration of various musculoskeletal tissues. Lay Summary Regenerative engineering aims to regenerate complex tissues to address the clinical challenge of organ damage. Tissue engineering has largely focused on the restoration and repair of individual tissues and organs, but over the past 25 years, scientific, engineering, and medical advances have led to the introduction of this new approach which involves the regeneration of complex tissues and biological systems such as a knee or a whole limb. While a number of excellent advanced biomaterials have been developed, the choice of biomaterials, however, has increased over the past years to include polymers that can be designed with a range of mechanical properties, degradation rates, and chemical functionality. The polyphosphazenes are one good example. Their chemical versatility and hydrogen bonding capability encourages blending with other biologically relevant polymers. The further development of Polyphosphazene-based blends will present a wide spectrum of advanced biomaterials that can be used as scaffolds for regenerative engineering and as well as other biomedical applications.

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Section: Synthesis Of Polyphosphazene – Mechanisms Of Polymerizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biodegradable Polyphosphazene-Based Blends for Regenerative Engineering

Ogueri

Ivirico

Nair

et al. 2017

Regen. Eng. Transl. Med.

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“…Despite the fact that PLGA has a proven track record with the FDA, and is therefore widely used, alternate biodegradable polymers with neutral or positive charge (e.g. polyketals, 33 polyphosphazenes, 34 or poly(β amino esters) 22 ) may actually be used to enable faster release of cationic agents, or more sustained release of anionic agents. Finally, co-encapsulation of excipients that would neutralize electrostatic interactions between PLGA and cationic peptides may accelerate release kinetics.…”

Section: Discussionmentioning

confidence: 99%

Positive charge of “sticky” peptides and proteins impedes release from negatively charged PLGA matrices

et al. 2015

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The influence of electrostatic interactions and/or acylation on release of charged (“sticky”) agents from biodegradable polymer matrices was systematically characterized. We hypothesized that release of peptides with positive charge would be hindered from negatively charged poly(lactic-co-glycolic acid) (PLGA) microparticles. Thus, we investigated release of peptides with different degrees of positive charge from several PLGA microparticle formulations, with different molecular weights and/or end groups (acid- or ester-terminated). Indeed, release studies revealed distinct inverse correlations between the amount of positive charge on peptides and their release rates from each PLGA microparticle formulation. Furthermore, we examined the case of peptides with net charge that changes from negative to positive within the pH range observed in degrading microparticles. These charge changing peptides displayed counterintuitive release kinetics, initially releasing faster from slower degrading (less acidic) microparticles, and releasing slower from the faster degrading (more acidic) microparticles. Importantly, trends between agent charge and release rates for model peptides also translated to larger, therapeutically relevant proteins and oligonucleotides. The results of these studies may improve future design of controlled release systems for numerous therapeutic biomolecules exhibiting positive charge, ultimately reducing time-consuming and costly trial and error iterations of such formulations.

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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

334

261

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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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Bioerodible polyphosphazenes and their medical potential

Cited by 136 publications

References 109 publications

Biodegradable Polyphosphazene-Based Blends for Regenerative Engineering

Biodegradable Polyphosphazene-Based Blends for Regenerative Engineering

Positive charge of “sticky” peptides and proteins impedes release from negatively charged PLGA matrices

Ring-Opening Polymerization—An Introductory Review

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