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Poly(L-lactic acid) (PLLA) is of interest in drug delivery applications for its biodegradable and biocompatible properties. Polymer-controlled drug delivery relies on the release of embedded drug molecules from the polymer matrix during its degradation. PLLA degradation exhibits an induction period, during which an insignificant amount of degraded products and embedded drug can be released. Due to this induction period, drug release is initially nonlinear, a complication in drug delivery applications. PLLA degradation is a function of crystallinity, such that control over its crystallinity tailors drug release over time. In this study, the effect of laser-induced PLLA crystallinity reduction on degradation is investigated. Samples having lower surface crystallinity are shown to have higher rates of molecular weight reduction and earlier mass loss than nonlasertreated samples, as observed from gel permeation chromatography and mass change. Wide-angle X-ray diffraction measurements show that crystallinity increases with degradation. A numerical model is implemented from hydrolysis and diffusion mechanisms to investigate the effect of laser irradiation on biodegradation. Controlled laser treatment of PLLA offers a method for constant drug release through the reduction of surface crystallinity.

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“…PLLA hydrolysis is accelerated by autocatalysis [5]. The rate of hydrolysis increases as the concentration of reaction products increases.…”

Section: Introductionmentioning

confidence: 99%

Effect of Laser-Induced Crystallinity Modification on Biodegradation Profile of Poly(L-Lactic Acid)

Hsu¹,

Tan²,

Yao

2013

Journal of Manufacturing Science and Engineering

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“…30,31 The hydrolysis of these polyesters produces shorter chains with acid and hydroxy terminal groups. 32 The hydrolytic degradation of synthetic and natural PHB in phosphate buffer at 70 °C was reported by Kurcok et al 29 The chemical microstructure has been revealed to have no substantial influence on the mechanism for hydrolytic degradation of atactic and isotactic PHB. Atactic PHB degraded faster than the semicrystalline polymer.…”

Section: Introductionmentioning

confidence: 92%

“…The explanation for this unexpected phenomenon was the hydrophobicity of paraffin, which generated an autocatalytic effect in which the acid end-groups catalyse cleavage of the ester and the concentration of terminal chain ends with acid termination increases in the polymer. 32,47,49,57 Water initially diffused into the sample to penetrate the polymer matrix, and the process of autocatalytic hydrolysis began. The degradation process for a thicker rigid PLA film (thickness of 300 μm) is faster than for the thin PLA film (thickness of 40 µm) used in the previous degradation experiment.…”

Section: Molar Mass Changesmentioning

confidence: 99%

Forensic Engineering of Advanced Polymeric Materials. Part 1 – Degradation Studies of Polylactide Blends with Atactic Poly[(R,S)-3-hydroxybutyrate] in Paraffin

Rydz

Wolna-Stypka

Adamus

et al. 2015

Chem.Biochem.Eng.Q.

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The degradation of the advanced polymeric materials: blends of polylactide with poly[(R,S)-3-hydroxybutyrate] was studied in paraffin (an ingredient used in cosmetics) and compared with the degradation of pure poly[(R,S)-3-hydroxybutyrate]. The interaction between the polymeric materials studied and the paraffin was monitored during the degradation experiments, and the effects of this interaction were reported. Gel permeation chromatography, atomic force microscopy, electrospray mass spectrometry, nuclear magnetic resonance, differential scanning calorimetry and thermal gravimetric analysis revealed that degradation of the investigated materials occurs in the presence of paraffin. In the blends, poly[(R,S)-3-hydroxybutyrate] content was found to extend the disintegration time, and for the blends with good miscibility, reduced the degradation rate in the first step of degradation.

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“…10,11 In the hydrolytic degradation of polyesters such as poly(lactic acid), the rate acceleration in loss of mass has been attributed to the increasing concentration of terminal carboxylic acid groups. 12 However, rate acceleration with liquid esters was demonstrated to arise by a physical mechanism whereby the product effectively aids in the solubilisation of the reactant. 13 Here, evidence was examined for acid autocatalysis in the hydrolysis of two solid esters with differing dissolution rates: D-gluconic acid δ-lactone and DL-lactide, the cyclic ester from which poly(lactic acid) can be synthesised.…”

Section: Page 2 Of 10mentioning

confidence: 99%