Biodegradable polymers for biomedical uses

Hayashi, Toshio

doi:10.1016/0079-6700(94)90030-2

Cited by 312 publications

(159 citation statements)

References 184 publications

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“…The rate of BC degradation is low and depends on several factors, including the availability of enzymes that degrade cellulose, cellulose crystallinity, the chemical composition of main chain and side groups of cellulose, the hydrophilic-hydrophobic balance, surface area, aggregation state and the shape and morphology of the material [26]. Cellulose is degraded in nature by fungal and microbial enzymes through hydrolase attack on the b(1-4) linkages [27].…”

Section: Cell Studymentioning

confidence: 99%

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Microporous bacterial cellulose as a potential scaffold for bone regeneration

et al. 2010

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a b s t r a c tNanoporous cellulose biosynthesized by bacteria is an attractive biomaterial scaffold for tissue engineering due to its biocompatibility and good mechanical properties. However, for bone applications a microscopic pore structure is needed to facilitate osteoblast ingrowth and formation of a mineralized tissue. Therefore, in this study microporous bacterial cellulose (BC) scaffolds were prepared by incorporating 300-500 lm paraffin wax microspheres into the fermentation process. The paraffin wax microspheres were subsequently removed, and scanning electron microscopy confirmed a microporous surface of the scaffolds while Fourier transform infrared spectroscopy verified the elimination of paraffin and tensile measurements showed a Young's modulus of approximately 1.6 MPa. Microporous BC and nanoporous (control) BC scaffolds were seeded with MC3T3-E1 osteoprogenitor cells, and examined by confocal microscopy and histology for cell distribution and mineral deposition. Cells clustered within the pores of microporous BC, and formed denser mineral deposits than cells grown on control BC surfaces. This work shows that microporous BC is a promising biomaterial for bone tissue engineering applications.

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Section: Cell Studymentioning

confidence: 99%

“…Chemical modification of cellulose has the potential to increase degradability by disrupting its higher ordered structure [26]. Cellulose itself is a neutral polysaccharide with no charged groups for molecular recognition.…”

Section: Cell Studymentioning

confidence: 99%

Microporous bacterial cellulose as a potential scaffold for bone regeneration

et al. 2010

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“…These biodegradable aliphatic polyesters have been widely used in biomedical and pharmaceutical applications such as surgery repair materials and drug delivery systems [6][7][8]. Among these aliphatic polyesters, PPDO is a biodegradable, aliphatic poly(ether-ester) usually prepared by ring-opening polymerization (ROP) with organometallic catalysts such as Sn(Oct) 2 .…”

Section: Introductionmentioning

confidence: 99%

Graft polymerization of p-dioxanone onto polyhydroxyethylaspartamide through ring-opening polymerization using organometallic and enzyme catalysts

Park

Ramaraj

Yoon

2012

Designed Monomers and Polymers

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The grafting of poly(p-dioxanaone) (PPDO) onto β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) was achieved, first, by synthesis of polysuccinimide (PSI) from DL-aspartic acid through thermal condensation polymerization, and then, followed by aminolysis of PSI to form PHEA with hydroxyl end groups, and finally the PPDO was grafted onto PHEA through these hydroxyl end groups by ring-opening polymerization (ROP) of PDO in the presence of tin octoate [Sn (Oct) 2 ] and Candida Antarctica Lipase B (Novozyme 435) catalysts. Evidence of grafting was obtained by comparing Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) analysis, polarized optical microscopy (POM), proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy, and solubility characteristics of PHEA with PPDO-grafted copolymers (PHEA-g-PPDO). The FT-IR spectroscopic analysis reveals the formation of ester linkage between PPDO and hydroxyl end groups of PHEA. TGA analysis shows a quite different thermal profile for grafted polymers. DSC and XRD results reveal the existence of graft copolymer in two different crystalline forms. POM shows banded spherulitic morphology for the graft copolymers. The grafting of PPDO was further confirmed by 1 H-NMR. Eventhough, graft copolymer was obtained by both these methods, the graft copolymer obtained by enzyme catalyzed ROP shows higher crystalline order, better spherulitic morphology, and solubility characteristics than that of the graft polymer obtained by organometal catalyzed ROP.

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“…In this study, the effects of specific GAGs on the expansion of CD34 + cord blood cells were studied in stroma-free cultures using a model GAG surface. GAGs were immobilized onto culture surfaces by forming insoluble ionic complexes with the amino-polysaccharide chitosan [15][16][17]. Human umbilical cord blood CD34 + cells were seeded onto the complex surfaces, and their proliferation and retention of CD34 expression were followed.…”

Section: Introductionmentioning

confidence: 99%

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

1999

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Recent studies have indicated that glycosaminoglycan (GAG) interactions with hematopoietic progenitors play a significant role in the regulation of hematopoiesis. However, the details of these interactions are not clear. In this study, we examined the role of soluble and immobilized GAGs in the proliferation of CD34 + cells. Chitosan, a cationic polysaccharide, was used to immobilize GAGs in ionic complex membranes. The GAGs studied were heparin, hyaluronate, and chondroitin sulfates A, B, and C. CD34-enriched umbilical cord blood cells were seeded onto tissue culture plates coated with the GAG-chitosan complex membranes. Cultures were maintained in medium supplemented with stem cell factor and interleukin 3 for up to six weeks, during which total and CD34 + cell numbers were determined by flow cytometry. Total cell number expansion ranged from 25-fold to 40-fold after six weeks. However, only heparin and chondroitin sulfate B (CSB) surfaces retained a significant CD34 + fraction. All other surfaces exhibited declines in CD34 expression, with negligible CD34 + percentages remaining after four weeks. In contrast, heparin and CSB surfaces exhibited CD34 + fractions as high as 90% after four weeks.GAG desorption studies indicated that the observed effects were partly mediated by desorbed GAGs in a concentration dependent manner. Subsequent studies showed that sustained high (160 g/ml) heparin levels had toxic effects, while the same concentration of CSB exhibited more rapid early proliferation of CD34 + cells. In conclusion, this culture system has demonstrated the ability to produce simultaneous proliferation and CD34 + cell enrichment of a partially purified cord blood population by controlling the nature and levels of GAG moieties to which the cells are exposed. The results indicate that specific GAGs can significantly influence the growth and differentiation characteristics of cultured CD34 + cells.

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Biodegradable polymers for biomedical uses

Cited by 312 publications

References 184 publications

Microporous bacterial cellulose as a potential scaffold for bone regeneration

Microporous bacterial cellulose as a potential scaffold for bone regeneration

Graft polymerization of p-dioxanone onto polyhydroxyethylaspartamide through ring-opening polymerization using organometallic and enzyme catalysts

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

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Biodegradable polymers for biomedical uses

Cited by 312 publications

References 184 publications

Microporous bacterial cellulose as a potential scaffold for bone regeneration

Microporous bacterial cellulose as a potential scaffold for bone regeneration

Graft polymerization of p-dioxanone onto polyhydroxyethylaspartamide through ring-opening polymerization using organometallic and enzyme catalysts

Maintenance of CD34 Expression During Proliferation of CD34 + Cord Blood Cells on Glycosaminoglycan Surfaces

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Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces