Reaction-diffusion degradation model for delayed erosion of cross-linked polyanhydride biomaterials

Domanskyi, Sergii; Poetz, Katie L.; Shipp, Devon A.; Privman, Vladimir

doi:10.1039/c5cp00473j

Cited by 16 publications

(17 citation statements)

References 40 publications

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“…More recently, investigators have begun to model the hydrolysis of cross-linked biodegradable polymers, such as cross-linked polyanhydrides, which were also predicted to degrade via a surface eroding mechanism [159]. These molecules have a long induction period of water uptake relative to their degradation rate.…”

Section: Figurementioning

confidence: 99%

Lifetime prediction of biodegradable polymers

Laycock

Nikolić

Colwell

et al. 2017

Progress in Polymer Science

475

364

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The determination of the safe working life of polymer materials is important for their successful use in engineering, medicine and consumer-goods applications. An understanding of the physical and chemical changes to the structure of widely-used polymers such as the polyolefins, when exposed to aggressive environments, has provided a framework for controlling their ultimate service lifetime by either stabilizing the polymer or chemically accelerating the degradation reactions. The recent focus on biodegradable polymers as replacements for more bio-inert materials such as the polyolefins in areas as diverse as packaging and as scaffolds for tissue engineering has highlighted the need for a review of the approaches to being able to predict the lifetime of these materials. In many studies the focus has not been on the embrittlement and fracture of the material (as it would be for a polyolefin) but rather the products of degradation, their toxicity and ultimate fate when in the environment, which may be the human body. These differences are primarily due to time-scale. Different approaches to the problem have arisen in biomedicine, such as the kinetic control of drug delivery by the bio-erosion of polymers, but the similarities in mechanism provide real prospects for the prediction of the safe service lifetime of a biodegradable polymer as a structural material. Common mechanistic themes that emerge include the diffusion-controlled process of water sorption and conditions for surface versus bulk degradation, the role of hydrolysis versus oxidative degradation in controlling the rate of polymer chain scission and strength loss and the specificity of enzyme-mediated reactions.

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Section: Figurementioning

confidence: 99%

Lifetime prediction of biodegradable polymers

Laycock

Nikolić

Colwell

et al. 2017

Progress in Polymer Science

475

364

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“…Modeling of the erosion and degradation is usually carried out by numerically solving diffusion-reaction equations that are based on the macroscopic diffusion coefficient and reaction rates. ,− ,− While this approach allows modeling of the surface and bulk erosion on the macroscopic level, it lacks molecular details and is missing specifics of coupling between water diffusion and degradation kinetics. This coupling becomes even more critical when one attempts to model degradation of microphase-separated copolymers.…”

Section: Introductionmentioning

confidence: 99%

Degradation of Films of Block Copolymers: Molecular Dynamics Simulations

et al. 2020

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Coarse-grained molecular dynamics simulations are used to study the degradation of films of copolymers in a selective solvent for one of the blocks. Simulations were designed to mimic the hydrolytic degradation of glycine, valine, and phenylalanine-based poly(ester urea)s. The analysis of the simulation results shows that the rate of copolymer degradation is a result of the interplay between chain-breaking kinetics, solvent diffusion, and swelling of the solvophilic domains. The evolution of the film structure during the degradation process was monitored by calculating the scattering function S(q) of the copolymer film. In the initial stages of the polymer degradation and swelling, the scattering function has a characteristic peak corresponding to a domain spacing of solvophilic and solvophobic domains. The solvent diffusion into the films results in a monotonic shift of the peak position to smaller q. This shift is accompanied by the increase in the scattering intensity at q ≪ 1 in such a way that the peak completely disappears at the later stages of film degradation with the function S(q) having two characteristic scaling regimes: S(q) ∼ 1/q 2 and S(q) ∼ 1/q 4 . At this stage of film degradation, the film is composed of the interconnected network of solvophobic domains. The number and weight average degree of polymerizations (DPs) of the copolymer fragments monotonically decrease with time. However, the dispersity (Đ) shows a nonmonotonic dependence. The copolymer degradation kinetics allows for universal description of the time dependence of the copolymer DP and the dispersity in terms of the fraction of the broken bonds.

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“…The anhydride bonds are extremely labile to hydrolysis and thus, the degradation of the surface anhydrides takes place much faster than its penetration into the bulk of the matrix. 31 Since the mass loss due to degradation is accompanied by a concomitant decrease in the sample dimensions, it is likely that the erosion takes place layer by layer from the surface of the matrix. 29 This is further corroborated by the kinetics of mass loss, as discussed in the following section.…”

Section: Hydrolytic Degradation Studiesmentioning

confidence: 99%

Physical insights into salicylic acid release from poly(anhydrides)

Dasgupta

Chatterjee

Madras

2016

Phys. Chem. Chem. Phys.

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Salicylic acid (SA) based biodegradable polyanhydrides (PAHs) are of great interest for drug delivery in a variety of diseases and disorders owing to the multi-utility of SA. There is a need for the design of SA-based PAHs for tunable drug release, optimized for the treatment of different diseases. In this study, we devised a simple strategy for tuning the release properties and erosion kinetics of a family of PAHs. PAHs incorporating SA were derived from related aliphatic diacids, varying only in the chain length, and prepared by simple melt condensation polymerization. Upon hydrolysis induced erosion, the polymer degrades into cytocompatible products, including the incorporated bioactive SA and diacid. The degradation follows first order kinetics with the rate constant varying by nearly 25 times between the PAH obtained with adipic acid and that with dodecanedioic acid. The release profiles have been tailored from 100% to 50% SA release in 7 days across the different PAHs. The release rate constants of these semi-crystalline, surface eroding PAHs decreased almost linearly with an increase in the diacid chain length, and varied by nearly 40 times between adipic acid and dodecanedioic acid PAH. The degradation products with SA concentration in the range of 30-350 ppm were used to assess cytocompatibility and showed no cytotoxicity to HeLa cells. This particular strategy is expected to (a) enable synthesis of application specific PAHs with tunable erosion and release profiles; (b) encompass a large number of drugs that may be incorporated into the PAH matrix. Such a strategy can potentially be extended to the controlled release of other drugs that may be incorporated into the PAH backbone and has important implications for the rational design of drug eluting bioactive polymers.

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Reaction-diffusion degradation model for delayed erosion of cross-linked polyanhydride biomaterials

Cited by 16 publications

References 40 publications

Lifetime prediction of biodegradable polymers

Lifetime prediction of biodegradable polymers

Degradation of Films of Block Copolymers: Molecular Dynamics Simulations

Physical insights into salicylic acid release from poly(anhydrides)

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