Thermoresponsive Interpolymeric Complex Assemblies from Co‐association of Linear PAAc Homopolymers with PNIPAAm Segments Containing PAAc‐Based Graft Copolymer

Chiang, Wen‐Hsuan; Hsu, Yuan‐Hung; Chen, Yiwei; Chern, Chorng–Shyan; Chiu, Hsin‐Cheng

doi:10.1002/macp.201100124

Cited by 5 publications

(4 citation statements)

References 33 publications

(51 reference statements)

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“…Remarkable hydrophobic association between PAAc and PNIPAAm segments thus evolved further induces the formation of colloidal assembly. Similar observations can be found in the literature. ,− Figure c illustrates 1 H NMR spectra of mixed copolymers A and B in D 2 O at pD 7.4 and 3.0, respectively, at 25 °C. As compared to that at pD 7.4, the signal intensity of the methyl protons (at δ 1.25 ppm) of PNIPAAm segments was appreciably reduced at pD 3.0, in agreement with the above postulation that PNIPAAm grafts are involved extensively in the development of hydrophobic dehydrated regions within polymeric assemblies.…”

Section: Resultssupporting

confidence: 87%

Dual Stimuli-Responsive Polymeric Hollow Nanogels Designed as Carriers for Intracellular Triggered Drug Release

Chiang

Huang

et al. 2012

Langmuir

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Dual stimuli-responsive hollow nanogel spheres serving as an efficient intracellular drug delivery platform were obtained from the spontaneous coassociation of two graft copolymers into the vesicle architecture in aqueous phase. Both copolymers comprise acrylic acid (AAc) and 2-methacryloylethyl acrylate (MEA) units as the backbone and either poly(N-isopropylacrylamide) (PNIPAAm) alone or both PNIPAAm and monomethoxypoly(ethylene glycol) (mPEG) chain segments as the grafts. The assemblies were then subjected to covalent stabilization within vesicle walls with ester-containing cross-links by radical polymerization of MEA moieties, thereby leading to hollow nanogel particles. Taking the advantage of retaining a low quantity of payload within polymer layer-enclosed aqueous chambers through the entire loading process, doxorubicin (DOX) in the external bulk phase can be effectively transported into the gel membrane and bound therein via electrostatic interactions with ionized AAc residues and hydrogen-bond pairings with PNIPAAm grafts at pH 7.4. With the environmental pH being reduced (e.g., from 7.4 to 5.0) at 37 °C, the extensive disruption of AAc/DOX complexes due to the reduced ionization of AAc residues within the gel layer and the pronounced shrinkage of nanogels enable the rapid release of DOX species from drug-loaded hollow nanogels. By contrast, the drug liberation at 4 °C was severally restricted, particularly at pH 7.4 at which the DOX molecules remain strongly bound with ionized AAc residues and PNIPAAm grafts. The in vitro characterizations suggest that the DOX-loaded hollow nanogel particles after being internalized by HeLa cells via endocytosis can rapidly release the payload within acidic endosomes or lysosomes. This will then lead to significant drug accumulation in nuclei (within 1 h) and a cytotoxic effect comparable to free drug. This work demonstrates that the novel DOX-loaded hollow nanogel particles show great promise of therapeutic efficacy for potential anticancer treatment.

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Section: Resultssupporting

confidence: 87%

Dual Stimuli-Responsive Polymeric Hollow Nanogels Designed as Carriers for Intracellular Triggered Drug Release

Chiang

Huang

et al. 2012

Langmuir

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“…Therefore, the increased particle size is primarily attributed to the development of the hybrid assemblies from the cooperative association of macromolecules with the citric acid-bearing SPIONs via massive hydrogen bonds between PNIPA grafts and un-ionized carboxyl groups of citric acid residues. Complementary hydrogen-bond pairings of PNIPA chain segments with the pairing targets containing carboxyl groups and the subsequent hydrophobic effect of supramolecular association thus induced have been extensively documented. ,,− The resultant nanohybrids are highly stabilized by the pronounced steric repulsion mechanism of the hydrated mPEG graft segments. The particle size distribution profiles of the hybrid assemblies determined by DLS are shown in Figure S3.…”

Section: Resultsmentioning

confidence: 99%

Superparamagnetic Hollow Hybrid Nanogels as a Potential Guidable Vehicle System of Stimuli-Mediated MR Imaging and Multiple Cancer Therapeutics

Chiang

Chen

et al. 2013

Langmuir

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Hollow hybrid nanogels were prepared first by the coassembly of the citric acid-coated superparamagnetic iron oxide nanoparticles (SPIONs, 44 wt %) with the graft copolymer (56 wt %) comprising acrylic acid and 2-methacryloylethyl acrylate units as the backbone and poly(ethylene glycol) and poly(N-isopropylacrylamide) as the grafts in the aqueous phase of pH 3.0 in the hybrid vesicle structure, followed by in situ covalent stabilization via the photoinitiated polymerization of MEA residues within vesicles. The resultant hollow nanogels, though slightly swollen, satisfactorily retain their structural integrity while the medium pH is adjusted to 7.4. Confining SPION clusters to such a high level (44 wt %) within the pH-responsive thin gel layer remarkably enhances the transverse relaxivity (r2) and renders the MR imaging highly pH-tunable. For example, with the pH being adjusted from 4.0 to 7.4, the r2 value can be dramatically increased from 138.5 to 265.5 mM(-1) s(-1). The DOX-loaded hybrid nanogels also exhibit accelerated drug release in response to both pH reduction and temperature increase as a result of the substantial disruption of the interactions between drug molecules and copolymer components. With magnetic transport guidance toward the target and subsequent exposure to an alternating magnetic field, this DOX-loaded nanogel system possessing combined capabilities of hyperthermia and stimuli-triggered drug release showed superior in vitro cytotoxicity against HeLa cells as compared to the case with only free drug or hyperthermia alone. This work demonstrates that the hollow inorganic/organic hybrid nanogels hold great potential to serve as a multimodal theranostic vehicle functionalized with such desirable features as the guidable delivery of stimuli-mediated diagnostic imaging and hyperthermia/chemotherapies.

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“…Given the aforementioned merits of PNIPAM and the advantage of convenient preparation by rapid development of controlled/living radical polymerization (CLRP), some well‐defined smart polymers based on PNIPAM have drawn considerable attention . The most versatile and efficient techniques, including atom transfer radical polymerization (ATRP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization, are applied by many researchers to prepare some well‐defined thermoresponsive polymers based on PNIPAM . To reduce the steric hindrance and the interaction of hydrogen bonds when preparing graft polymers based on PNIPAM with controlled length and high graft density, choosing an efficient and specific method under mild conditions to obtain these polymers is a fascinating subject for chemists.…”

Section: Introductionmentioning

confidence: 99%

Effects of graft length and density of well‐defined graft polymers on the thermoresponsive behavior and self‐assembly morphology

Jiang

Zhang

Yan

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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A series of well‐defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)‐graft‐poly(N‐isopropylacrylate) (PGMA‐g‐PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self‐assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co‐relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA45‐g‐PNIPAM20 and PGMA45‐g‐PNIPAM46 with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA45‐g‐PNIPAM(73, 50%) shows a spherical‐like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self‐assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self‐assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2442–2453

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Thermoresponsive Interpolymeric Complex Assemblies from Co‐association of Linear PAAc Homopolymers with PNIPAAm Segments Containing PAAc‐Based Graft Copolymer

Cited by 5 publications

References 33 publications

Dual Stimuli-Responsive Polymeric Hollow Nanogels Designed as Carriers for Intracellular Triggered Drug Release

Dual Stimuli-Responsive Polymeric Hollow Nanogels Designed as Carriers for Intracellular Triggered Drug Release

Superparamagnetic Hollow Hybrid Nanogels as a Potential Guidable Vehicle System of Stimuli-Mediated MR Imaging and Multiple Cancer Therapeutics

Effects of graft length and density of well‐defined graft polymers on the thermoresponsive behavior and self‐assembly morphology

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