Synthesis, isothermal crystallization and micellization of mPEG–PCL diblock copolymers catalyzed by yttrium complex

Xie, Weihui; Zhu, Weipu; Shen, Zhiquan

doi:10.1016/j.polymer.2007.09.021

Cited by 49 publications

(50 citation statements)

References 24 publications

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“…In this study, molecular weight of the copolymer was controlled by adjusting the molar ratio of ε-CL and MPEG. In addition, the critical micelle concentration of the copolymer decreased with increasing PCL length which was consistent with published literature [23] . CAP has been extensively investigated in pharmacy and neuroscience [30] due to its varied pharmacological activities.…”

Section: Discussionsupporting

confidence: 92%

“…The signal at δ 3.649 ppm was assigned to the -CH 2 protons of the PEG chain. In addition, the peaks at δ 2.294-2.319, 1.619-1.678, 1.384-1.410, and 4.050-4.072 ppm were attributed to the various methylene protons of the PCL units corresponding to the results reported in the literature [23,24] . The Mn obtained from 1 H NMR was calculated to be approximately 16 000 g/mol by comparing the peak intensity at approximately 2.31 with 3.65 ppm.…”

Section: Resultssupporting

confidence: 78%

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Oral delivery of capsaicin using MPEG-PCL nanoparticles

et al. 2014

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Aim: To prepare a biodegradable polymeric carrier for oral delivery of a water-insoluble drug capsaicin (CAP) and evaluate its quality. Methods: CAP-loaded methoxy poly (ethylene glycol)-poly(ε-caprolactone) nanoparticles (CAP/NPs) were prepared using a modified emulsification solvent diffusion technique. The quality of CAP/NPs were evaluated using transmission electron microscopy, powder X-ray diffraction, differential scanning calorimetry and Fourier transform infrared techniques. A dialysis method was used to analyze the in vitro release profile of CAP from the CAP/NPs. Adult male rats were orally administered CAP/NPs (35 mg/kg), and the plasma concentrations of CAP were measured with a validated HPLC method. The morphology of rat gastric mucosa was studied with HE staining. Results: CAP/NPs had an average diameter of 82.54±0.51 nm, high drug-loading capacity of 14.0%±0.13% and high stability. CAP/NPs showed a biphasic release profile in vitro: the burst release was less than 25% of the loaded drug within 12 h followed by a more sustained release for 60 h. The pharmacokinetics study showed that the mean maximum plasma concentration was observed 4 h after oral administered of CAP/NPs, and approximately 90 ng/mL of CAP was detected in serum after 36 h. The area under the curve for the CAP/NPs group was approximately 6-fold higher than that for raw CAP suspension. Histological studies showed that CAP/NPs markedly reduced CAP-caused gastric mucosa irritation. Conclusion: CAP/NPs significantly enhance the bioavailability of CAP and markedly reduce gastric mucosa irritation in rats.

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Section: Discussionsupporting

confidence: 92%

Section: Resultssupporting

confidence: 78%

Oral delivery of capsaicin using MPEG-PCL nanoparticles

et al. 2014

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“…The characteristic peak at 4.25 ppm belongs to the methylene protons of the MPEG-CH 2 -CH 2 -O-CO-CL oligomer, indicating the successful synthesis of the MPEG-CL oligomer. 26 The composition of the oligomers was determined from the integration area ratio of the -CH 2 -group (peak b, ~4.10 ppm) in the CL units to the -CH 2 -CH 2 -group (peak c, ~3.63 ppm). Table I shows the structural parameters of the samples.…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, for the oligomer, α-CD preferentially included CL units due to a greater inclusion affinity for more hydrophobic molecules, 35 so more EG units were remained as hydrophilic framework to form gel. The oligomers could form micelles in aqueous solution due to the amphiphilic property of diblock copolymers, 26,36,37 which can also play an important role in the instantaneous gelation of α-CD with the oligomer in aqueous solution. A cooperative effect of rapid complexation rate of α-CD with the oligomer due to the low-molecular-weight character, hydrophobic interactions between crystalline inclusion complexes, as well as the hydrophobic aggregation between the CL units can result in instantaneous gelation and formation of a stable supramolecular hydrogel.…”

Section: Resultsmentioning

confidence: 99%

Supramolecular hydrogels instantaneously formed by inclusion complexation between amphiphilic oligomers and α-cyclodextrins

Zhao

Lee

2009

Macromol. Res.

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Supramolecular hydrogels were instantaneously fabricated by mixing aqueous solutions of α-cyclodextrins (α-CDs) and amphiphilic methoxy (polyethylene glycol) (MPEG)-ε-caprolactone (CL) oligomer, which was synthesized via the ring-opening polymerization of the CL monomer using low-molecular-weight MPEG (M n of MPEG=2,000 g/mol) as an initiator. The supramolecular structure of the hydrogels was revealed by X-ray diffraction (XRD) analyses. Rheological studies of the hydrogels revealed an elastic character when the number of CL units in the oligomer was more than 2, and the obtained hydrogels showed high storage modulus but relatively low shearing viscosity due to the low-molecular-weight character of the oligomer, which was more preferable for use as an injectable delivery system. The physical properties of the hydrogels could be modulated by controlling the chain morphology and concentration of the oligomers, as well as the feed molar ratio of the oligomer to α-CD. The components of the supramolecular hydrogels are biocompatible and can readily be eliminated from the body. These features render the supramolecular hydrogels suitable as drug delivery systems and tissue engineering scaffolds.

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“…[23] In another example, PEG 114 -PCL diblock copolymers with varied PCL chain length (1900-18300 g/mol), self-assembled in aqueous solution to form regular spherical micelles in the size range of 30-80 nm. [20] The critical micellization concentration (CMC) was determined to be 0.9-6.9 mg/L, which increased with decreasing PCL length. CMC values of these PEG-PCL diblock copolymers are generally low, indicating the potential application as drug delivery carriers.…”

Section: Diblock Copolymers and Their Self-assembliesmentioning

confidence: 99%