Characterization of PLGA microspheres for the controlled delivery of IL-1α for tumor immunotherapy

Chen, Limor; Apte, Ron N.; Cohen, Smadar

doi:10.1016/s0168-3659(96)01496-4

Cited by 99 publications

(45 citation statements)

References 19 publications

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“…In Figure 10B, the homogenous, heterogeneous, and transition regimes predicted in the current study are compared to experimental observations of homogenous and heterogeneous diffusion in different sized samples (Chen et al, 1997;Grizzi et al, 1995;Lu et al, 1999;Park, 1995;Shirazi et al, 2014;Spenlehauer et al, 1989;Vey et al, 2008). Grizzi et al (1995) has proposed a range of 200-300 μm as a critical thickness above which the poly(D,L-lactic acid) polymers (plate, film, microsphere)(which have a similar chemical structure and degradation behaviour to PLGA) undergo heterogeneous degradation.…”

Section: Discussionmentioning

confidence: 76%

“…However, Park et al (1995) has shown the heterogeneous degradation of PLGA microspheres with diameters less than 10 μm. The heterogeneous degradation of PLGA microspheres has been also demonstrated in a study by Chen et al (1997) for PLGA microspheres with diameters of 50-70 μm. While the predictions in the current study are in broad agreement with observations, the disparities in experimentally observed critical length for transition between heterogeneous and homogenous degradation highlight the need for further experimental investigation of both the mechanical and molecular behaviour of PLGA during degradation.…”

Section: Discussionmentioning

confidence: 78%

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Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Shirazi

Ronan

Rochev

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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Publication InformationShirazi, RN,Ronan, W,Rochev, Y,McHugh, P (2016) 'Modelling the degradation and elastic properties of poly (lacticco-glycolic AbstractScaffolding plays a critical rule in tissue engineering and an appropriate degradation rate and sufficient mechanical integrity are required during degradation and healing of tissue. This paper presents a computational investigation of the molecular weight degradation and the mechanical performance of poly(lactic-co-glycolic acid) (PLGA) films and tissue engineering scaffolds. A reactiondiffusion model which predicts the degradation behaviour is coupled with an entropy-based mechanical model which relates the Young's modulus and the molecular weight. The model parameters are determined based on experimental data for in-vitro degradation of a PLGA film. Microstructural models of three different scaffold architectures are used to investigate the degradation and mechanical behaviour of each scaffold. Although the architecture of the scaffold does not have a significant influence on the degradation rate, it determines the initial stiffness of the scaffold. It is revealed that the size of the scaffold strut controls the degradation rate and the mechanical collapse. A critical length scale due to competition between diffusion of degradation products and autocatalytic degradation is determined to be in the range 2-100 μm. Below this range, slower homogenous degradation occurs; however, for larger samples monomers are trapped inside the sample and faster autocatalytic degradation occurs.

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 78%

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Shirazi

Ronan

Rochev

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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“…By incorporating microspheres into the network, we create an independent mechanism to tune drug delivery, while maintaining the structure of the scaffold. Drug delivery from microspheres can be easily controlled by composition and size as has been described before [103][104][105]. Furthermore, by using the spraying technique it is conceivable that more than one composition of microsphere may be introduced for delivery of multiple drugs.…”

Section: Discussionmentioning

confidence: 99%

Preferential cell response to anisotropic electro-spun fibrous scaffolds under tension-free conditions

English

Azeem

Gaspar

et al. 2011

J Mater Sci: Mater Med

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Anisotropic alignment of collagen fibres in musculoskeletal tissues is responsible for the resistance to mechanical loading, whilst in cornea is responsible for transparency. Herein, we evaluated the response of tenocytes, osteoblasts and corneal fibroblasts to the topographies created through electro-spinning and solvent casting. We also evaluated the influence of topography on mechanical properties. At day 14, human osteoblasts seeded on aligned orientated electro-spun mats exhibited the lowest metabolic activity (P \ 0.001). At day 5 and at day 7, no significant difference was observed in metabolic activity of human corneal fibroblasts and bovine tenocytes respectively seeded on different scaffold conformations (P [ 0.05). Osteoblasts and corneal fibroblasts aligned parallel to the direction of the aligned orientated electro-spun mats, whilst tenocytes aligned perpendicular to the aligned orientated electro-spun mats. Mechanical evaluation demonstrated that aligned orientated electro-spun fibres exhibited significant higher stress at break values than their random aligned counterparts (P \ 0.006) and random orientated electro-spun fibres exhibited significant higher strain at break values than the aligned orientated scaffolds (P \ 0.006). While maintaining fibre structure, we also developed a co-deposition method of spraying and electro-spinning, which enables the incorporation of microspheres within the three-dimensional structure of the scaffold.

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“…Although the heterogeneous degradation of the 0.12 mm film and the 1 mm plate were not directly inspected here using scanning electron microscopy, the similar degradation rate for the molecular weight of all three thicknesses is consistent with the heterogeneous degradation of PLGA for the thicknesses considered here. Similarly, experimental studies have shown heterogeneous degradation for films of 300 μm [25] and 5-100 μm [12], and for 50-70 μm microspheres [26]. However, there is no consensus in the literature on the length scale for transition between homogenous and heterogeneous degradation.…”

Section: Critical Diffusion Length Scalementioning

confidence: 99%

Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance

Shirazi

Aldabbagh

Ronan

et al. 2016

J Mater Sci: Mater Med

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(2016). Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance. Journal of Materials Science: Materials in Medicine, 27(10), 1-12. doi: 10.1007/s10856-016-5760-z PublisherSpringer Verlag The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the PLGA material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of PLGA films for thicknesses larger than 100 μm.

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Characterization of PLGA microspheres for the controlled delivery of IL-1α for tumor immunotherapy

Cited by 99 publications

References 19 publications

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Preferential cell response to anisotropic electro-spun fibrous scaffolds under tension-free conditions

Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance

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