Preparation of thermo- and pH-responsive star copolymers via ATRP and its use in drug release application

Rwei, Syang‐Peng; Chuang, Yo-Ying; Way, Tun-Fun; Chiang, Whe-Yi; Hsu, Shu-Ping

doi:10.1007/s00396-014-3436-0

Cited by 24 publications

(25 citation statements)

References 20 publications

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“…Although the micelle formation due to IAM composition units in the star copolymer was proposed in the previous work [24] based on the data of the particle diameter, the current work shows the synthesized copolymer has a core–shell structure. On the other hand, the random copolymer containing IAM composition units in the other previous work [23] does not show micelle formation.…”

Section: Discussioncontrasting

confidence: 54%

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Synthesis and Drug Delivery Application of Thermo- and pH-Sensitive Hydrogels: Poly(β-CD-co-N-Isopropylacrylamide-co-IAM)

et al. 2016

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Copolymerization of N-isopropylacrylamide (NIPAM), itaconamic acid (IAM; 4-amino-2-methylene-4-oxobutanoic acid) and β-cyclodextrin was investigated in this study. β-cyclodextrin was at first modified by reacting with allyl glycidyl ether to substitute its OH end groups with moieties containing double bonds to facilitate the subsequent radical copolymerization with NIPAM and IAM. It was reported that poly(NIPAM-IAM) can respond to the change of temperature as well as pH value. In this study, the structure of β-cyclodextrin was introduced to poly(NIPAM-IAM) copolymers because of its cavity structure capable of encapsulating a variety of drug molecules. The tri-component copolymers, poly(CD-NIPAM-IAM), were synthesized with different monomeric ratios of NIPAM/IAM/β-CD and the hydrogels of the tri-component copolymers were also synthesized by additionally adding N,N′-methylenebisacrylamide as a cross-linking agent. The results show that the lower critical solution temperature (LCST) of the copolymer (or hydrogel) increases as the molar fraction of IAM increases. The transmission electron microscopic (TEM) images of linear copolymers (no cross-linking) show that molecules undergo self-assembly to have a distinct core–shell structure, compared to poly(CD-NIPAM) which contains no IAM. On the other hand, the scanning electron microscopic (SEM) images of hydrogels show that the pores gradually become sheet-like structures as the molar fraction of IAM increases to enhance the water absorption capacity. In order to exhibit the thermal and pH sensitivities of poly(CD-NIPAM-IAM) as the drug carrier, the drug release of the newly synthesized hydrogels at 37 °C and different pH values, pH = 2 and pH = 7.4, was investigated using atorvastatin which was used primarily as a lipid-lowering drug. The drug release experimental result shows that poly(CD-NIPAM-IAM) as a drug carrier was pH-sensitive and has the largest release rate at pH = 7.4 at 37 °C, indicating it is useful to release drugs in a neutral or alkaline (intestinal) environment.

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Section: Discussioncontrasting

confidence: 54%

“…In previous studies, itaconamic acid (IAM; 4-amino-2-methylene-4-oxobutanoic acid) was used to contribute pH-sensitivity to N -isopropylacrylamide-based (NIPAM-based) copolymers [23,24,25]. The applicability of controlled drug delivery of copolymers having various structures, such as hyperbranched or star structures, was investigated.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Drug Delivery Application of Thermo- and pH-Sensitive Hydrogels: Poly(β-CD-co-N-Isopropylacrylamide-co-IAM)

et al. 2016

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“…We expected to see sharp changes in the phase transition, as shown in Figure (b,c), compared to a copolymer with larger PDI. In addition, our earlier study using radical polymerization to synthesize poly(N‐isopropylacrylamide‐co‐itaconamic acid) showed a PDI of about 1.8, and another study using atomic transfer radical polymerization to synthesize hyperbranched copolymers hyper‐ g ‐(N‐isopropylacrylamide‐co‐itaconamic acid) showed PDI values of about 1.34–1.36. This indicated that the advantage of using controlled living radical polymerization was a low PDI.…”

Section: Resultsmentioning

confidence: 93%

“…Thermosensitive polymers, a class of smart polymers, respond to changes in temperature by swelling or deswelling; they are used extensively in nanobiotechnology and biomedical applications . Poly( N ‐isopropyl acrylamide) (PNIPAAm) is a well‐known representative thermosensitive polymer with a good thermal sensitivity and favorable biocompatibility.…”

Section: Introductionmentioning

confidence: 99%

Thermosensitive copolymer synthesized by controlled living radical polymerization: Phase behavior of diblock copolymers of poly(N‐isopropyl acrylamide) families

Rwei

Chuang

Way

et al. 2015

J of Applied Polymer Sci

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In this study, we prepared a series of thermosensitive polymers with low polydispersity index (PDI) values by nitroxidemediated controlled radical polymerization (NMRP) with 2,2,6,6-tetramethyl-1-piperdinyloxy nitroxide (TEMPO) as a stable nitroxide-free radical. Poly(N-isopropyl acrylamide) (PNIPAAm)-block-poly(N-tert-butyl acrylamide) (PNTBA) was successfully synthesized, first, through polymerization with N-isopropyl acrylamide to obtain the reactive polymer PNIPAAm-TEMPO and, second, through polymerization by the addition of N-tert-butyl acrylamide (NTBA). The added molar fraction of NTBA during the second polymerization was adjusted accordingly to obtain the final polymerization product, a thermosensitive polymer (PNIPAAm-block-PNTBA), which had a targeted lower critical solution temperature (LCST). The result shows that the synthesis method used in this study effectively controlled the formation of the polymer to obtain a low PDI. The thermosensitive block copolymer, PNIPAAm-b-PNTBA (molar ratio 5 9:1), with LCSTs in the range 27.7-39.88C, was obtained through controlled living radical polymerization with PNIPAAm-TEMPO. Specifically, the 5 wt % aqueous solution of PNIPAAm-b-PNTBA (molar ratio 5 9:1) had an LCST of 37.48C; this was close to body temperature, 378C. The 5 wt % aqueous solution of PNIPAAm-b-PNTBA (molar ratio 5 9:1) showed potential for use in biomedical applications.

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“…Polymeric systems which respond to the combination of two or multiple stimuli would be more attractive for release of the guest materials. However, a limited number of reports are available in the literature concerning dual stimuli‐responsive polymers, which contain polymeric chains and functional groups, capable of responding to temperature as well as pH in a single polymeric system . Such dual‐stimuli responsive systems gain the advantage of increased temperature and decreased pH environments of cancer tissues compared to the normal healthy tissues to release the encapsulated guest materials without providing the external stimulus source.…”

Section: Introductionmentioning

confidence: 99%

Temperature and pH dual stimuli responsive PCL-b-PNIPAAm block copolymer assemblies and the cargo release studies

Patil

Wadgaonkar

2017

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

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A new atom transfer radical polymerization (ATRP) initiator, namely, 2‐(1‐(2‐azidoethoxy)ethoxy)ethyl 2‐bromo‐2‐methylpropanoate containing both “cleavable” acetal linkage and “clickable” azido group was synthesized. Well‐defined azido‐terminated poly(N‐isopropylacrylamide)s (PNIPAAm‐N3)s with molecular weights and dispersity in the range 11,000–19,000 g mol−1 and 1.20–1.28, respectively, were synthesized employing the initiator by ATRP. Acetal containing PCL‐b‐PNIPAAm block copolymer was obtained by alkyne–azide click reaction of azido‐terminated PNIPAAm‐N3 with propargyl‐terminated PCL. Critical aggregation concentration (CAC) of PCL‐b‐PNIPAAm copolymer in aqueous solution was found to be 8.99 × 10−6 M. Lower critical solution temperature (LCST) of PCL‐b‐PNIPAAm copolymer was found to be 32 °C which was lower than that of the precursor PNIPAAm‐N3 (36.4 °C). The effect of dual stimuli viz. temperature and pH on size and morphology of the assemblies of PCL‐b‐PNIPAAm block copolymer revealed that the copolymer below LCST assembled in spherical micelles which subsequently transformed to unstable vesicles above the LCST. Heating these assemblies above 40 °C led to the precipitation of PCL‐b‐PNIPAAm block copolymer. Whereas, at decreased pH, micelles of PCL‐b‐PNIPAAm copolymer disintegrate due to the cleavage of acetal linkage and precipitation of hydrophobic hydroxyl‐terminated PCL. The encapsulated pyrene release kinetics from the micelles of synthesized PCL‐b‐PNIPAAm copolymer was found to be faster at higher temperature and at lower pH. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1383–1396

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Preparation of thermo- and pH-responsive star copolymers via ATRP and its use in drug release application

Cited by 24 publications

References 20 publications

Synthesis and Drug Delivery Application of Thermo- and pH-Sensitive Hydrogels: Poly(β-CD-co-N-Isopropylacrylamide-co-IAM)

Synthesis and Drug Delivery Application of Thermo- and pH-Sensitive Hydrogels: Poly(β-CD-co-N-Isopropylacrylamide-co-IAM)

Thermosensitive copolymer synthesized by controlled living radical polymerization: Phase behavior of diblock copolymers of poly(N‐isopropyl acrylamide) families

Temperature and pH dual stimuli responsive PCL-b-PNIPAAm block copolymer assemblies and the cargo release studies

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