Temperature‐induced spontaneous sol–gel transitions of poly(<scp>D,L</scp>‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(<scp>D,L</scp>‐lactic acid‐co‐glycolic acid) triblock copolymers and their end‐capped derivatives in water

Yu, Lin; Chang, Guangtao; Zhang, Huan; Ding, Jiandong

doi:10.1002/pola.21876

Cited by 173 publications

(171 citation statements)

References 49 publications

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“…Based on the central PEG block with MW of 1000, a series of PLGA-PEG-PLGA triblock copolymers were synthesized in our previous work and the sol-gel transition temperature increased from about 10 to 25°C by varying the PEG/PLGA ratios from 1/2.8 to 1/2.1. 42 Similar reports could also be seen in the literature by other groups, for instance, Singh et al 43 The gel window is very important, because a sample with a low sol-gel transition temperature is difficult to handle and inject, whereas a sample with a sol-gel transition temperature higher than the body temperature cannot be gelled after injection. Different block ratios as synthesized in this paper might even lead to loss of thermogelling ability.…”

Section: Introductionsupporting

confidence: 72%

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Mixing a Sol and a Precipitate of Block Copolymers with Different Block Ratios Leads to an Injectable Hydrogel

et al. 2009

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A facile method to obtain a thermoreversible physical hydrogel was found by simply mixing an aqueous sol of a block copolymer with a precipitate of a similar copolymer but with a different block ratio. Two ABA-type triblock copolymers poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) were synthesized. One sample in water was a sol in a broad temperature region, while the other in water was just a precipitate. The mixture of these two samples with a certain mix ratio underwent, however, a sol-to-gel-to-precipitate transition upon an increase of temperature. A dramatic tuning of the sol-gel transition temperature was conveniently achieved by merely varying mix ratio, even in the case of a similar molecular weight. Our study indicates that the balance of hydrophobicity and hydrophilicity within this sort of amphiphilic copolymers is critical to the inverse thermal gelation in water resulting from aggregation of micelles. The availability of encapsulation and sustained release of lysozyme, a model protein by the thermogelling systems was confirmed. This "mix" method provides a very convenient approach to design injectable thermogelling biomaterials with a broad adjustable window, and the novel copolymer mixture platform is potentially used in drug delivery and other biomedical applications.

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Section: Introductionsupporting

confidence: 72%

“…The detailed procedure has been described by our previous papers. 34,42 In this study, using two PEG blocks (MW 1500 and 1000) and a given LA/GA ratio (4/1), a couple of PLGA-PEG-PLGA triblock copolymers with the PEG/ PLGA ratios of 1/1.7 and 1/3.1 were synthesized and studied. NMR Measurements.…”

Section: Methodsmentioning

confidence: 99%

Mixing a Sol and a Precipitate of Block Copolymers with Different Block Ratios Leads to an Injectable Hydrogel

et al. 2009

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“…[44,45] A series of PLGA-PEG-PLGA triblock copolymers with several different end caps (hydroxy, acetyl, propionyl, and butanoyl groups) was synthesized and characterized. Triblock copolymers containing acetate and propionate groups exhibited a sol-to-gel transition as a function of temperature, whereas the copolymer containing the butyrate group precipitated in water.…”

Section: Poly(ethylene Glycol) (Peg)/polyestermentioning

confidence: 99%

Injectable Biodegradable Hydrogels

Nguyen

Lee

2010

Macromolecular Bioscience

422

343

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Injectable biodegradable copolymer hydrogels, which exhibit a sol–gel phase transition in response to external stimuli, such as temperature changes or both pH and temperature (pH/temperature) alterations, have found a number of uses in biomedical and pharmaceutical applications, such as drug delivery, cell growth, and tissue engineering. These hydrogels can be used in simple pharmaceutical formulations that can be prepared by mixing the hydrogel with drugs, proteins, or cells. Such formulations are administered in a straightforward manner, through site‐specific control of release behavior, and the hydrogels are compatible with biological systems. This review will provide a summary of recent progress in biodegradable temperature‐sensitive polymers including polyesters, polyphosphazenes, polypeptides, and chitosan, and pH/temperature‐sensitive polymers such as sulfamethazine‐, poly(β‐amino ester)‐, poly(amino urethane)‐, and poly(amidoamine)‐based polymers. The advantages of pH/temperature‐sensitive polymers over simple temperature‐sensitive polymers are also discussed. A perspective on the future of injectable biodegradable hydrogels is offered.magnified image

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“…With the intention of inventing biomimetic systems capable of drug release following biological need, hydrogel-based drug delivery systems [4,6,14,15,17] and stimuli-sensitive intelligent hydrogels [18][19][20] have been developed. The types of physically self-assembled hydrogels, in which the microstructure is made up of arranged micelles, are taking an increasingly prominent part in drug delivery and controlled release [3,4,7,14].…”

Section: Introductionmentioning

confidence: 99%

Polymeric Nanostructures as Colloidal Drug Delivery Systems: Thermosensitive Hydrogels Containing Self-Assembled Micelles

Hossein¹

2015

J Nanomed Nanotechnol

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Polymeric nanostructures for drug delivery applications including smart hydrogels and stealth micelles have been developed to overcome many obstacles in the way of timing and targeting the delivery to fulfill therapeutic potentiality of chemicals. The purpose of this investigation is to prepare and characterize novel nanoparticle-based colloidal products composed of biocompatible polymers to use for rate-controlled release and targeted/spatial drug delivery systems, aiming specifically at drug delivery via mucosal routes. We formulated the new products with inert and biocompatible polymers including sodium carboxymethylcellulose (NaCMC) and polysorbates. The synthesis process was performed by heating/cooling method, as a type of physical cross-linking method for producing hydrogel, in three steps to optimize physical and chemical characteristics of the products to make them suitable for delivery through mucosal routes. A series of nanoparticle-based colloidal products in the form of liquid suspensions were developed, and from all three steps, thirty-nine samples were selected and rheologically investigated by bench-top experiments. A freeze-thawing method was applied to two samples of product III10 for five and one repeated cycles sequentially. Test tube inversion method was also carried out on all the produced gels. Most of the products are new types of temperaturesensitive, smart, physically self-assembled hydrogels and took the forms of sol, gel (opaque and transparent), and precipitate. However, these hydrogels show opposite gelation property to customary temperature-sensitive gels. The product of five repeated freezing-thawing cycles is also thermoreversible gel with a high mechanical stability and swelling capacity, as opposed to the product of one cycle. Some types of produced hydrogels behave like a ternary system. The products of this work, with microstructure consisting of the polymeric chains of sodium carboxymethylcellulose and a large-scale self-assembly of micellar structures of polysorbates incorporated within a polymer network, show major efficacy of site-specific and controlled release drug delivery system.

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Temperature‐induced spontaneous sol–gel transitions of poly(D,L‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(D,L‐lactic acid‐co‐glycolic acid) triblock copolymers and their end‐capped derivatives in water

Cited by 173 publications

References 49 publications

Mixing a Sol and a Precipitate of Block Copolymers with Different Block Ratios Leads to an Injectable Hydrogel

Mixing a Sol and a Precipitate of Block Copolymers with Different Block Ratios Leads to an Injectable Hydrogel

Injectable Biodegradable Hydrogels

Polymeric Nanostructures as Colloidal Drug Delivery Systems: Thermosensitive Hydrogels Containing Self-Assembled Micelles

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