Controlled Thioacyl Group Transfer (TAGT) Polymerization of Cyclic Sulfide:  Novel Approach to AB Diblock Copolymers by the Combination of RAFT and TAGT Polymerizations

Nagai, Atsushi; Koike, Naoyuki; Kudo, Hiroto; Nishikubo, Tadatomi

doi:10.1021/ma071533w

Cited by 34 publications

(27 citation statements)

References 16 publications

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“…The ideal development of molecular masses with monomer conversion considering the insertion reaction only, which in fact features all characteristics of a living/ controlled polymerization proceeding via thioacyl group transfer (TAGT), [34] can be described by Equation 2:…”

Section: Resultsmentioning

confidence: 99%

“…After drying over Na 2 SO 4 the solvent was evaporated and the resulting residue was washed with THF and dried in vacuo yielding a white, finely dispersed solid (1. 22 , and C 24 ), 133.8 (C 10 and C 31 ), 131.7 (C 16 , C 20 , C 21 , and C 25 ), 129.8 (C 12 and C 29 ), 128.0 (C 2 , C 4 , C 37 , and C 39 ), 127.3 (C 13 and C 28 ), 127.2 (C 1 , C 5 , C 36 , and C 40 ), 121.2 (C 11 and C 30 ), 113.2 (C 9 and C 32 ), 69.31 (C 7 and C 34 …”

Section: Synthesis Of the Bcimentioning

confidence: 99%

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On the Mechanism of the Ring‐Expansion Polymerization of Thiiranes

Schuetz¹,

Vana²

2011

Macro Chemistry & Physics

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Ring polymers are synthesized using a cyclic bifunctional thioester as initiator for REP of thiiranes. PMT yields satisfactory results, whereas polymerization with MT appears to develop dead polymeric material as by‐product and TBMT gives only negligible conversion rates. The process produces high yields and high conversion rates. The corresponding molecular weight distributions show increasing broadening and multimodal character with increasing reaction time due to thermodynamically controlled ring‐merging reactions between macrocycles. The polymerization rate of PMT obeys a pseudo first‐order kinetics with an activation energy of 38.8 kJ mol−1. 1H NMR, ESI‐MS, and glass transition temperatures independent of the molecular weight demonstrate the presence of cyclic polymer. magnified image

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Section: Resultsmentioning

confidence: 99%

Section: Synthesis Of the Bcimentioning

confidence: 99%

On the Mechanism of the Ring‐Expansion Polymerization of Thiiranes

Schuetz¹,

Vana²

2011

Macro Chemistry & Physics

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“…Poly(propylene sulfide) was synthesized using the RAFT chain transfer agent CEP through the TAGT polymerization method [22]. Briefly, PS (0.30 mL, 3.8 mmol), CEP (24.9 mg, 0.095 mmol), TPPCl (7.1 mg, 0.019 mmol), and NMP (0.95 mL) were placed into a flame-dried ampoule equipped with a three-way stopcock and degassed for 30 min with three freeze-pump-thaw cycles.…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

“…PEG-b-PPS micelles were shown to enable sustained, slow release of the hydrophobic drug cycolsporin A, but, to our knowledge, these or similar polymers have not been rigorously investigated for triggered release of hydrophobic drug cargo in response to different ROS. Furthermore, a thioacyl group transfer (TAGT) method [22] was utilized here that enables pairing of the anionic ring opening polymerization of PPS with the RAFT polymerization of the hydrophilic polymer block. RAFT is amenable to use with a wide variety of monomers [23], and here, DMA was chosen for the corona forming polymer block due to its solubility in water and low toxicity [24, 25].…”

Section: 0 Introductionmentioning

confidence: 99%

Poly(PS-b-DMA) micelles for reactive oxygen species triggered drug release

Gupta

Meyer

Nelson

et al. 2012

Journal of Controlled Release

157

144

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A new micelle drug carrier that consists of a diblock polymer of propylene sulfide (PS) and N,N-dimethylacrylamide (poly(PS74−b-DMA310)) has been synthesized and characterized for site-specific release of hydrophobic drugs to sites of inflammation. Propylene sulfide was first polymerized using a thioacyl group transfer (TAGT) method with the RAFT chain transfer agent (CTA) 4-cyano-4-(ethylsulfanylthiocarbonylsulfanyl) pentanoic acid (CEP), and the resultant poly(PS74−CEP) macro-CTA was used to polymerize a second polymer block of DMA using reversible addition-fragmentation chain transfer (RAFT). The formation of the poly(PS74−b-DMA310) diblock polymer was confirmed by 1H NMR spectra and gel permeation chromatography (GPC). poly(PS74−b-DMA310) formed 100 nm micelles in aqueous media as confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Micelles loaded with the model drugs Nile red and DiO were used to demonstrate the ROS-dependent drug release mechanism of these micelles following treatment with hydrogen peroxide (H2O2), 3-morpholinosydnonimine (SIN-1), and peroxynitrite. These oxidants were found to oxidize the micelle PPS core, making it more hydrophilic and triggering micelle disassembly and cargo release. Delivery of poly(PS74−b-DMA310) micelles dual-loaded with the Förster Resonance Energy Transfer (FRET) fluorophore pair DiI and DiO was used to prove that endogenous oxidants generated by lipopolysaccharide (LPS)-treated RAW 264.7 macrophages significantly increased release of nanocarrier contents relative to macrophages that were not activated. In vitro studies also demonstrated that the poly(PS74−b-DMA310) micelles were cytocompatible across a broad range of concentrations. These combined data suggest that the poly(PS74−b-DMA310) micelles synthesized using a combination of TAGT and RAFT have significant potential for site-specific drug delivery to tissues with high levels of oxidative stress.

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“…To prepare PPS as previously described [34, 41], propylene sulfide (3.16 mL, 40.4 mmol), ECT (52 mg, 0.20 mmol), TPPCl (tetraphenylphosphonium chloride – Ph 4 P + Cl − ) (14.9 mg, 0.040 mmol), and dry NMP (N-methyl pyrolidone) (10 mL) were placed in a dry glass ampoule equipped with a magnetic stirring bar, and the solution was degassed by three freeze-evacuate-thaw cycles. The reaction mixture was stirred at 60°C for 20 hours, and the resulting polymer (Suppl.…”

Section: Methodsmentioning

confidence: 99%

ROS-responsive microspheres for on demand antioxidant therapy in a model of diabetic peripheral arterial disease

et al. 2015

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A new microparticle-based delivery system was synthesized from reactive oxygen species (ROS)-responsive poly(propylene sulfide) (PPS) and tested for “on demand” antioxidant therapy. PPS is hydrophobic but undergoes a phase change to become hydrophilic upon oxidation and thus provides a useful platform for ROS-demanded drug release. This platform was tested for delivery of the promising anti-inflammatory and antioxidant therapeutic molecule curcumin, which is currently limited in use in its free form due to poor pharmacokinetic properties. PPS microspheres efficiently encapsulated curcumin through oil-in-water emulsion and provided sustained, on demand release that was modulated in vitro by hydrogen peroxide concentration. The cytocompatible, curcumin-loaded microspheres preferentially targeted and scavenged intracellular ROS in activated macrophages, reduced in vitro cell death in the presence of cytotoxic levels of ROS, and decreased tissue-level ROS in vivo in the diabetic mouse hind limb ischemia model of peripheral arterial disease. Interestingly, due to the ROS scavenging behavior of PPS, the blank microparticles also showed inherent therapeutic properties that were synergistic with the effects of curcumin in these assays. Functionally, local delivery of curcumin-PPS microspheres accelerated recovery from hind limb ischemia in diabetic mice, as demonstrated using non-invasive imaging techniques. This work demonstrates the potential for PPS microspheres as a generalizable vehicle for ROS-demanded drug release and establishes the utility of this platform for improving local curcumin bioavailability for treatment of chronic inflammatory diseases.

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Controlled Thioacyl Group Transfer (TAGT) Polymerization of Cyclic Sulfide: Novel Approach to AB Diblock Copolymers by the Combination of RAFT and TAGT Polymerizations

Cited by 34 publications

References 16 publications

On the Mechanism of the Ring‐Expansion Polymerization of Thiiranes

On the Mechanism of the Ring‐Expansion Polymerization of Thiiranes

Poly(PS-b-DMA) micelles for reactive oxygen species triggered drug release

ROS-responsive microspheres for on demand antioxidant therapy in a model of diabetic peripheral arterial disease

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