Thermogelling Poly(caprolactone-<i>b</i>-ethylene glycol-<i>b</i>-caprolactone) Aqueous Solutions

Bae, Soo Jin; Suh, Ju Myung; Sohn, Youn Soo; Bae, You Han; Kim, Sung Wan; Jeong, Byeongmoon

doi:10.1021/ma050489m

Cited by 279 publications

(268 citation statements)

References 22 publications

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“…A similar trend was observed for a poly(caprolactone-b-ethylene glycol-b-caprolactone) (PCL±PEG±PCL) aqueous solution, which undergoes a sol-to-gel transition as the temperature increases to 30 C. [12] The viscosity of a gel steadily increases as the pH increases from pH 2±8 at the same concentration (20 wt.-% in water). The viscosity (g¢) of the aqueous polymer solution (30 wt.-%) at 37 C as a function of pH is shown in Figure 3a.…”

Section: ±1supporting

confidence: 65%

Thermogelling Multiblock Poloxamer Aqueous Solutions with Closed‐Loop Sol–Gel–Sol Transitions on Increasing pH

Suh¹,

Bae²,

Jeong

2005

Advanced Materials

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The thermogelling properties of aqueous polymer solutions have been hot topics of research due to their potential biomedical applications as well as to interest in understanding sol±gel transition mechanisms.[1] In particular, poloxamer, a triblock copolymer of poly(ethylene glycol)±poly(propylene glycol)±poly(ethylene glycol), and its derivatives, such as poloxamer-g-poly(acrylic acid) (Smart Gel), 3,4-dihydroxyphenylalanine (DOPA)-conjugated poloxamers, and biodegradable multiblock poloxamers, have been investigated.[2]Aqueous solutions of the above polymers are free-flowing sols at low temperature, whereas they turn into gels at physiological temperature by a heat-induced sol-to-gel transition. Therefore, aqueous polymer solutions containing drugs or cells have been proposed as injectable reservoir systems.[3] However, small-tissue adhesion and blockage of a long needle, especially a catheter, by gelation during injection of the formulation of the drug or cell limits their application. In addition, the pH in our body varies from 1±8 depending on the site as well as pathological condition. For example, vaginal pH is 3.7±5.5 and tumoral pH is~5.7±7.4. [4,5] Considering the above facts, we designed a multiblock poloxamer (MBP) with carboxylic acids and investigated the gelation characteristics as a function of pH and temperature. The synthetic route (Scheme 1) of the MBP shows that two moles of carboxylic acid groups are generated by one mole of terephthalic anhydride in the coupling reaction.Dynamic rheological analysis showed that the MBP aqueous solution (30 wt.-%) did not undergo appreciable change in dynamic viscosity (g¢) as the temperature was increased to 45 C at pH 7.4, indicating that the sol-to-gel transition did not occur. The increased hydrophilicity of the ionized carboxylic acid groups solubilize the MBP at pH 7.4. To see the effect of pH change on gelation, the viscosity of MBP (30 wt.-%) was measured as a function of pH and temperature (Fig. 1). The abrupt increase in viscosity at 25±30 C indicates the sol-to-gel transition of the MBP aqueous solution in a pH range of 4±6. Interestingly, the gel phase is observed in a specific pH range of 4±6 at 37 C. At low pH (< 3) and high pH (> 7.4), an appreciable increase in viscosity, that is, a solto-gel transition, was not observed.pH-and temperature-sensitive polymers such as poly(N-isopropylacrylamide-co-acrylic acid); poly(styrene-co-maleic anhydride) (SMA) grafted to poly(ethylene glycol) (PEG) (SMAg-PEG); and poly(N-vinylcaprolactam-co-methacrylic acid) have been reported.[6±8] They form gels at low pH and high temperature. However, there is no report of a polymer with a closed-loop gel phase, where the gel exists at a certain pH range and becomes a sol phase in both low-and high-pH regions.To get some idea of the closed-loop pH-dependent behavior, we hypothesized two opposing forces. First, as the pH increases, carboxylic acid (±COOH) is ionized to its conjugate carboxylate anion (±COO ± ), which increases the hydrophilicity of the MBP and makes th...

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Section: ±1supporting

confidence: 65%

Thermogelling Multiblock Poloxamer Aqueous Solutions with Closed‐Loop Sol–Gel–Sol Transitions on Increasing pH

Suh¹,

Bae²,

Jeong

2005

Advanced Materials

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“…67 The difference was attributed to the different micellar structure. The core and the shell of the micelles formed in the ABA triblock copolymer consisted of the hydrophobic CL and the hydrophilic EO segments, respectively.…”

Section: Aba Versus Bab Triblock Copolymersmentioning

confidence: 99%

Tuning the gelation of thermoresponsive gels

Constantinou

Georgiou

2016

European Polymer Journal

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Thermoresponsive gels are exciting polymeric materials with many biomedical applications in medical devices, drug delivery, tissue engineering and bio-printing. Also, they have great potential to be used in 3-D printing and thus in the fabrication of many different devices and materials. As it is crucial for the application of these gels to be able to control and tailor the gelation temperature and concentration this was the main focus and point of discussion of this feature article. Thus, it is discussed in detail how by varying the molar mass, composition, stereochemistry and architecture the thermoresponsive properties of these gels are altered.

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“…Recently, PEG-PCL-PEG and PCL-PEG-PCL (Scheme 5) triblock copolymers have been introduced, and aqueous solutions thereof showed a clear sol-to-gel-to-turbid sol transition with an increase in temperature. [31,32] DLS and 13 C NMR studies indicated that the clear sol-to-gel transition arose from micellar aggregation, whereas the gel-to-turbid sol transition was driven by the breakage of the core-shell structure. Because of differences in structural topology, PCL-PEG-PCL had a higher G 0 (10 000 Pa) ( Figure 4) than did PEG-PCL-PEG (100 Pa) ( Figure 5).…”

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

confidence: 99%

Injectable Biodegradable Hydrogels

Nguyen

Lee

2010

Macromolecular Bioscience

416

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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Thermogelling Poly(caprolactone-b-ethylene glycol-b-caprolactone) Aqueous Solutions

Cited by 279 publications

References 22 publications

Thermogelling Multiblock Poloxamer Aqueous Solutions with Closed‐Loop Sol–Gel–Sol Transitions on Increasing pH

Thermogelling Multiblock Poloxamer Aqueous Solutions with Closed‐Loop Sol–Gel–Sol Transitions on Increasing pH

Tuning the gelation of thermoresponsive gels

Injectable Biodegradable Hydrogels

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