Effect of PEG–PLLA diblock copolymer on macroporous PLLA scaffolds by thermally induced phase separation

Kim, Hyun Do; Bae, Eun Hee; Kwon, Ick Chan; Pal, Ravindra R.; Nam, Jae Do; Lee, Sang Soo

doi:10.1016/j.biomaterials.2003.09.011

Cited by 140 publications

(69 citation statements)

References 32 publications

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“…PEG has often been used as a soluble polymeric modifier in organic synthesis [8,[14][15][16]. Numerous researches have been carried out on copolymerization of PLA and PEG as drug carrier for controlled release [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

Ouyang

Kang

Yin

et al. 2009

Front. Mater. Sci. China

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In this work, chemically bonded poly(D, Llactide)-polyethylene glycol-poly(D, L-lactide) (PLA-PEG-PLA) triblock copolymers with various PEG contents and PLA homopolymer were synthesized via melt polymerization, and were confirmed by FTIR and 1 H-NMR results. The molecular weight and polydispersity of the synthesized PLA and PLA-PEG-PLA copolymers were investigated by gel permeation chromatography. Hydrophilicity of the copolymers was identified by contact angle measurement. PLA-PEG-PLA and PLA microparticles loaded with and without PTX were then produced via solution enhanced dispersion by supercritical CO 2 (SEDS) process. The effect of the PEG content on the particle size distribution, morphology, drug load, and encapsulation efficiency of the fabricated microparticles was also studied. Results indicate that PLA and PLA-PEG-PLA microparticles all exhibit sphere-like shape with smooth surface, when PEG content is relatively low. The produced microparticles have narrow particle size distributions and small particle sizes. The drug load and encapsulation efficiency of the produced microparticles decreases with higher PEG content in the copolymer matrix. Moreover, high hydrophilicity is found when PEG is chemically attached to originally hydrophobic PLA, providing the produced drug-loaded microparticles with high hydrophilicity, biocompatibility, and prolonged circulation time, which are considered of vital importance for vesselcirculating drug delivery system.

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Section: Introductionmentioning

confidence: 99%

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

Ouyang

Kang

Yin

et al. 2009

Front. Mater. Sci. China

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“…Therefore, it is widely used in medical area [1][2][3][4] as an important biomaterial. But it also has some flaws.…”

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confidence: 99%

Isothermal Crystallization Behavior of the Poly(L-lactide) Block in Poly(L-lactide)-Poly(ethylene glycol) Diblock Copolymers: Influence of the PEG Block as a Diluted Solvent

Yang

Zhao

Liu

et al. 2006

Polym J

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ABSTRACT:Isothermal crystallization kinetics and morphology of the poly(L-lactide) block in poly(L-lactide)-poly(ethylene glycol) diblock copolymers were studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM), respectively. The results were compared with that of the PLLA homopolymer. The introduction of the PEG block accelerated the crystallization rate of the PLLA block and promoted to form ring-banded spherulites. The analysis of isothermal crystallization kinetics has shown that the PLLA homopolymer accorded with the Avrami equation. But the PLLA block of the diblock copolymers deviated from the Avrami equation, which resulted from increasing of the crystallization rate and occurring of the second crystallization process. The equilibrium melting temperature (T o m ) of the PLLA block fell with its molecular weight decreasing. The conditions to obtain more regular ring-banded spherulites were below: the sample was the PLLA block of LA 5 EG 5 ; the crystallization temperature was about from 95 C to 100 C, which almost corresponded to regime II. Poly(L-lactide)(PLLA) is possessed of many predominant properties, such as biodegradability, biocompatibility, innocuity, tissue absorbability and so on. Therefore, it is widely used in medical area 1-4 as an important biomaterial. But it also has some flaws. For example, bad watersolubility, friability etc. Moreover, the properties are not able to meet the demand for expandedness of its application area. In order to improve its property, the synthesis of PLLA-based block copolymer is one of the most important ways. Poly(ethylene glycol) (PEG) is the simplest polyether. It has good biocompatibility, blood-compatibility, hydrophilicity and flexibility. 5,6 Hydrophilic PEG is introduced to form block copolymer which hopes to improve hydrophilicity, biocompatibility and other properties.7-10 Therefore, PLLA-PEG block copolymers have attracted many researchers' attention and have been studied on their properties and application. 11-15Although crystallization process of block copolymer that have double-crystallizable blocks is more complex than other block copolymer systems, the studies on crystallization process and morphology also attracted many people's attention in recent years owing to their important meaning in practical application. [16][17][18][19] As a double-crystallizable block copolymer, it is out of question that the properties and application of PLLA-PEG block copolymers have intimate relations with their crystallization process, crystallinity and crystallization morphology. Therefore, studying them is the indispensable contents. Fujiwara conducted detailed investigation on the crystallizationinduced morphological change, macromolecular selforganization process and crystalline structure. [20][21][22] Lee reported that PLLA and PEG blocks were phase separated, and the crystallization behavior of one block was markedly affected by the presence of the other block. 23 Luo thought that the crystallization morphology was deeply depen...

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“…It should be noted that for simplicity reasons, the moduli for the transversely isotropic case (E 3 and C 11 in Eqs. [7][8][9][10][11][12][13] are represented by E z and H A , respectively. Figure 5 shows a comparison between the fits obtained based on purely isotopic and transversely isotropic biphasic models.…”

Section: Biphasic Parameter Estimationmentioning

confidence: 99%

“…A variety of techniques is currently being employed for fabrication of porous polymeric scaffolds, including phase separation [10,11], gas foaming [12], porogen leaching [13], fiber bonding [14], emulsion freeze-drying [15], or a combination of these techniques [16][17][18]. While the conventional scaffold fabrication techniques can produce highly porous scaffolds, they have very limited control over scaffold architecture and pore interconnectivity.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication of 3D‐plotted polymeric scaffolds in functional tissue engineering

Yousefi¹,

Gauvin²,

Sun³

et al. 2007

Polymer Engineering & Sci

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Regenerating the load‐bearing tissues requires 3D scaffolds that balance the temporary mechanical function with the biological requirements. In functional tissue engineering, designing scaffolds with biomimetic mechanical properties could promote tissue ingrowth since the cells are sensitive to their local mechanical environment. This work aims to design scaffolds that mimic the mechanical response of the biological tissues under physiological loading conditions. Poly(L‐lactide) (PLLA) scaffolds with varying porosities and pore sizes were made by the 3D‐plotting technique. The scaffolds were tested under unconfined ramp compression to compare their stress profile under load with that of bovine cartilage. A comparison between the material parameters estimated for the scaffolds and for the bovine cartilage based on the biphasic theory enabled the definition of an optimum window for the porosity and pore size of these constructs. Moreover, the finite element prediction for the stress distribution inside the scaffolds, surrounded by the host cartilaginous tissue, demonstrated a negligible perturbation of the stress field at the site of implantation. The finite element modeling tools in combination with the developed methodology for optimal porosity/pore size determination can be used to improve the design of biomimetic scaffolds. POLYM. ENG. SCI., 47:608–618, 2007. © 2007 Society of Plastics Engineers.

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Effect of PEG–PLLA diblock copolymer on macroporous PLLA scaffolds by thermally induced phase separation

Cited by 140 publications

References 32 publications

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

Isothermal Crystallization Behavior of the Poly(L-lactide) Block in Poly(L-lactide)-Poly(ethylene glycol) Diblock Copolymers: Influence of the PEG Block as a Diluted Solvent

Design and fabrication of 3D‐plotted polymeric scaffolds in functional tissue engineering

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