Hydrolytic and enzymatic degradation of poly(γ-glutamic acid) hydrogels and their application in slow-release systems for proteins

Fan, Kesuo; Gonzales, Denis; Sevoian, Martin

doi:10.1007/bf02070694

Cited by 43 publications

(36 citation statements)

References 18 publications

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“…γ-PGA was first functionalised with the organosilane GPTMS, where the carboxylic acid of the 30 polymer was reacted with the epoxy group on the GPTMS by ring opening esterification. During the functionalisation process it was found that the inorganic functional group trimethoxysilane on GPTMS had hydrolysed and partially condensed to other GPTMS molecules forming Si-O-Si 35 bridging oxygens. Using 29 Si solid-state magic angle spinning (MAS) NMR it was possible to quantify the proportion of condensed and free silicate species.…”

Section: Resultsmentioning

confidence: 99%

“…Surprisingly, decreasing the concentration of GPTMS resulted in an increase in D c , where the contrary was expected. Although the concentration of species for potential condensation increased, the amount of water remained 35 constant therefore there was significant competition for water from the increased GPTMS and hence only partial condensation was possible. Doubling the reaction time increased D c by a factor of 1.7, as a result of increased time for the molecules to move around and condense.…”

Section: Resultsmentioning

confidence: 99%

“…Synthetic constructs for bone regeneration have been made from inorganic and organic materials. [9][10][11] One example of an inorganic construct for bone regeneration is the sol-gel 35 derived bioactive glasses. 7 Jones et al developed macroporous bioactive glass foams that can form an HCA layer after 72 h of immersion in SBF.…”

Section: Synthetic Bone Graft Substitutesmentioning

confidence: 99%

“…1) is a little known polymer in the field of tissue engineering. 35,36 Reports have indicated that sequences of 10 glutamic acid residues are found in bone at the end of collagen fibrils and that they have a role in HCA nucleation. 37,38 This property of γ-PGA has been successsfully utilised to fabricate γ-PGA/HCA composites by the immersion of the polymer in a solution containing calcium and phosphate.…”

Section: Figmentioning

confidence: 99%

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Synthesis of bioactive class II poly(γ-glutamic acid)/silica hybrids for bone regeneration

Poologasundarampillai

Ionescu

Tsigkou

et al. 2010

J. Mater. Chem.

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Bone grafts are commonly used to regenerate bone in defect sites resulting from disease or trauma but there is clinical need for artificial materials that will be readily available and reduce pain and recovery time for the patient. Current artificial bone graft materials are bioactive ceramics and glasses, which are too brittle for bone defects that experience cyclic load. The synthesis of a new nanocomposite material is described that has the potential of being a tough off-the-shelf artificial bone graft that can regenerate a bone defect and have enough flexibility to press-fit into place. The poly(γ-glutamic acid)/bioactive silica hybrid material with composition 40 wt% organic and 60 wt% bioactive inorganic (composition 70 mol% SiO 2 and 30 mol% CaO) was synthesised using a sol-gel route. The potential advantage of a hybrid material over conventional composites is the molecular scale interactions between the bioactive inorganic and the tough degradable organic. The organic and inorganic chains were covalently crosslinked using an organosilane that has an organic functionality to bond to poly(γ-glutamic acid) (γ-PGA) and an alkoxysilane group that condenses with the inorganic phase. The covalent cross-linking (class II hybrid)is required to control the dissolution and improve mechanical properties of the material. The two key variables, the concentration of cross-linking agent and the addition of calcium, were investigated by 29 Si solid-state NMR and electron microscopy. The hybrid materials were bioactive in simulated body fluid (SBF) with a hydroxy carbonate apatite (HCA) layer detected after immersion for 72 h. The hybrid material favours cell attachment and is not cytotoxic as demonstrated by culture of the osteosarcoma cell line SaOs-2 on the material for 4 days. This journal is

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Synthetic Bone Graft Substitutesmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis of bioactive class II poly(γ-glutamic acid)/silica hybrids for bone regeneration

Poologasundarampillai

Ionescu

Tsigkou

et al. 2010

J. Mater. Chem.

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“…5 Crosslinked PGA gels were reported by many researchers for medical or environmental applications, such as drug-release systems [6][7][8][9][10] and water treatment reagents. 11 Crosslinked PGA gels were prepared using g-irradiation 6,7,11,12 or crosslinking reagents, such as dihalogenoalkanes, 8,9 alkyldiamines 10 and diisocyanates. 13 Crosslinking reagents are generally more useful than g-irradiation because special facilities are not required.…”

Section: Introductionmentioning

confidence: 99%

Bio-based biodegradable hydrogels prepared by crosslinking of microbial poly(γ-glutamic acid) with L-lysine in aqueous solution

Murakami

Aoki

Matsumura

2011

Polym J

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Bio-based biodegradable hydrogels were prepared by crosslinking microbial homo poly(amino acid), poly(c-glutamic acid) (PGA), with L-lysine in a one-pot synthesis in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) at 25 1C. The crosslinking was carried out in aqueous solution and the yields of the gels prepared with DMT-MM were higher than those prepared with water-soluble carbodiimide. The water absorption of the PGA gels crosslinked with L-lysine ranged from 300 to 2100 g/g. The water absorption of the PGA gel was affected by the amount of crosslinker and DMT-MM, which had an effect on the crosslinking density of the PGA gel. It was confirmed in a hydrolysis test in a buffer of pH 9 at 37 1C that the obtained gel that was crosslinked with L-lysine by amide bonds was more resistant to hydrolysis than the gel crosslinked by ester bonds. biochemical oxygen demand-biodegradability of the PGA gel crosslinked with L-lysine reached 60% in activated sludge at 25 1C.

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Structural change and swelling mechanism of pH-sensitive hydrogels based on chitosan andD,L-lactic acid

Wirsén

Albertsson

1999

J. Appl. Polym. Sci.

111

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Graft copolymerization of D,L-lactic acid (LA) onto chitosan (CS) was attempted without using a catalyst. pH-sensitive hydrogels were obtained which are based on two different components: a natural polymer and a synthetic polymer. These polyester substituents provide the basis for hydrophobic interactions that contribute to the formation of hydrogels. The swelling mechanisms in enzyme-free simulated gastric fluid (SGF, pH 2.2) or simulated intestinal fluid (SIF, pH 7.4) at 37°C were investigated. Meanwhile, structural changes of the graft copolymers in the different pH buffers were studied by FTIR, and these are discussed together with the swelling mechanisms. The effect of pH on the water uptake of hydrogel was investigated by using McIlvaine buffer with the same ionic strength. The morphological change of hydrogels in different aqueous solutions is investigated by scanning electron microscopy (SEM).

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Hydrolytic and enzymatic degradation of poly(γ-glutamic acid) hydrogels and their application in slow-release systems for proteins

Cited by 43 publications

References 18 publications

Synthesis of bioactive class II poly(γ-glutamic acid)/silica hybrids for bone regeneration

Synthesis of bioactive class II poly(γ-glutamic acid)/silica hybrids for bone regeneration

Bio-based biodegradable hydrogels prepared by crosslinking of microbial poly(γ-glutamic acid) with L-lysine in aqueous solution

Structural change and swelling mechanism of pH-sensitive hydrogels based on chitosan andD,L-lactic acid

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