Stimuli-responsive polymersomes and nanoreactors

Wei

Macro Chemistry & Physics

et al. 2018

To reveal the importance of hydrophobic block in morphology transition of responsive copolymers, four well‐defined ABC terpolymers with the same poly(dimethylamino ethyl methacrylate) (PDMAEMA) and PEG segments are synthesized by sequential RAFT polymerization. Poly (n‐hexyl methacrylate) (PnHMA), poly(n‐butyl methacrylate) (PnBMA), poly(ethyl methacrylate) (PEMA), and poly(methyl methacrylate) (PMMA), with glass transition temperatures of −5, 20, 65, and 100 °C, respectively, are selected as hydrophobic segments. The structures and compositions of four terpolymers, that is, mPEG45‐b‐PnHMA29‐b‐PDMAEMA28(EHD), mPEG45‐b‐PnBMA28‐b‐PDMAEMA32 (EBD), mPEG45‐b‐PEMA31‐b‐PDMAEMA30 (EED), and mPEG45‐b‐PMMA30‐b‐PDMAEMA29 (EMD), are confirmed by gel permeation chromatography and 1H NMR. Their morphology transitions in water are investigated via a combination of UV‐vis spectroscopy, light scattering, zeta potential measurements, and cryogenic transmission electron microscopy. All terpolymers can form spherical micelle by direct dissolution in acidic water. However, the spherical micelles of EBD and EHD progressively switch to cylinders and vesicles upon variations of external pH and temperature. In contrast, the spherical micelles of EMD and EED reversibly form larger aggregates when the temperature is above the cloud point of PDMAEMA in basic water. This study demonstrates the importance of hydrophobic block on the morphology transition of responsive copolymers.

Section: Introductionmentioning

confidence: 99%

Morphology Transition of Dual‐Responsive ABC Terpolymer in Water: Effect of Hydrophobic Block

Wei

Macro Chemistry & Physics

et al. 2018

“…15 In particular, materials showing dual temperature and pH response characteristics have been developed for drug delivery applications, 16 demonstrating efficient tailored release. 17,18 The area of stimuli-triggered drug delivery has witnessed significant advances, with systems such as polymersomes, 19 dendrimers 20 and nanocomposite hydrogels 21 all showing promising results. Among the different matrices, polymeric nanogels have been widely investigated 22 since they were first reported in 1935, 23 owing to their cargo-releasing applications.…”

Section: Introductionmentioning

confidence: 99%

An l-proline based thermoresponsive and pH-switchable nanogel as a drug delivery vehicle

Salinas

Resmini

2018

Polym. Chem.

The synthesis and characterisation of a novel dual stimuli-responsive nanogel, based on thermoresponsive N-n-propylacrylamide and an L-proline based monomer acting as a pH-switcher, is reported here. The effect of the crosslinker/co-monomer ratios was studied to demonstrate the relationship between the chemical structure, degree of hydrophobicity and physico-chemical characteristics of the nanogels. Tailoring of the thermoresponsive properties was achieved by altering crosslinker N,N'-methylenebis (acrylamide) content between 10 and 50 mol%, in combination with three thermoresponsive monomers N-n-isopropylacrylamide, N-n-propylacrylamide and N-acryloylpyrrolidine. A library of 25 different combinations of monomers and crosslinkers was obtained and characterised by dynamic light scattering and UV-Vis spectroscopy. The nanogel based on N-n-propylacrylamide and 10 mol% crosslinker was then co-polymerised with an L-proline based monomer to introduce a pH-switch. This nanogel was obtained with <10 nm particle size and a VPTT ca. 43°C, and was used to demonstrate a drug delivery capability using Nile Blue A as a model drug. Detailed studies demonstrated maximum drug release at lower pH and 43°C, thus confirming the dual stimuli switch.

“…Studies of static and dynamic self-assembly processes [1] have led to the preparation of av ariety of tunable soft materials [2] for applicationi nthe areas of medicine, [3] catalysis, [4] and molecular electronics. [11,15] Accordingly,i ti se xpected that (a) the invention of new amphiphilic/bolaamphiphilic moleculesa long with (b) a more complete understandingo fr ecognition eventsa tv esicular surfaces [16] and (c) development of new ways for governing the trafficking of molecules across vesicular membranes [17] will lead to even better performing soft materialsa kin to those encountered in the natural world. [10] Importantly,t hesen anosized "capsules", with membrane composed of molecules packed into one or multiple layers, surround as pace that can be used to store molecular cargoes for (a) targeted delivery [11] or (b) compartmentalization of chemical reactions.…”

mentioning

confidence: 99%

“…[5] In essence,a mphiphilic/bolaamphiphilic molecules, [6] block co-polymers [7] and supra-amphiphiles, [8] with the shapeo fatruncated cone, [9] have at endencyt oa ggregate in polar aqueousm edia and form vesicular assemblies. [11,15] Accordingly,i ti se xpected that (a) the invention of new amphiphilic/bolaamphiphilic moleculesa long with (b) a more complete understandingo fr ecognition eventsa tv esicular surfaces [16] and (c) development of new ways for governing the trafficking of molecules across vesicular membranes [17] will lead to even better performing soft materialsa kin to those encountered in the natural world. [4b, 12] The operation of vesicular assemblies is, in part, af unction of recognition processes taking place at their curvedt wo-dimensional surface [13] as well as the membrane's permeability [14] forr egulating molecular trafficking to/fromt he vesicular reservoir.I ndeed, there has been ac onsiderable interest toward understanding both of these processes, resulting in the preparation of av ariety of stimuli-responsives oft materials.…”

mentioning

confidence: 99%

Multivalent and Photoresponsive Assembly of Dual‐Cavity Baskets in Water

Wang

Neal

Chen

et al. 2017

Chemistry A European J

Large unilamellar vesicles [1] , composed of bolaamphiphilic baskets 1, were found to complex photoresponsive guest 3 and divalent 4 to, respectively, give stable vesicular assemblies [1 -3] and [1 -4 ] . With the assistance of H NMR spectroscopy, electron microscopy, and dynamic light scattering, it was deduced that [1 -3] vesicles comprise ternary [1 -3] organized into a curved membrane in which a pair of baskets entraps a laterally positioned dicationic 3. In the case of [1 -4 ] vesicles, however, the spectroscopic results suggest that three guest molecules 4 insert vertically between four baskets 1 to give pentanary [1 -4 ] packed into the membrane of [1 -4 ] . Importantly, nanostructured [1 -3] and [1 -4 ] retain rhodamine B (RhB) in their reservoir (fluorescence microscopy) and can be switched from one into another using UV light, with a disproportionate release of RhB dye. The reported complexes, organized into photoresponsive capsular materials, are rather unprecedented, demonstrating the potential of multivalency for creating functional structures of great interest in the areas of catalysis and delivery.