Poly(2-isopropyl-2-oxazoline)-<i>b</i>-poly(lactide) (PiPOx-<i>b</i>-PLA) Nanoparticles in Water: Interblock van der Waals Attraction Opposes Amphiphilic Phase Separation

Pooch, Fabian; Sliepen, Marjolein; Knudsen, Kenneth Dahl; Nyström, Bo; Tenhu, Heikki; Winnik, Françoise M.

doi:10.1021/acs.macromol.8b02558

Cited by 8 publications

(4 citation statements)

References 38 publications

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“…Routine physicochemical micelle characterization methods often fail to detect intercomponent complexation. The phenomenon can reveal itself through the emergence of unique macroscopic properties, as reported recently in a study of poly-lactide- b -poly(-2-isopropyl-2-oxazoline) micelles in water . In the course of this study of azopyridine-end-modified PNIPAM dispersed in neutral aqueous media, we recorded an exceptionally fast cis-to-trans thermal relaxation of the chromophore attributed to the formation of H-bonds between AzPy and PNIPAM chains.…”

Section: Discussionsupporting

confidence: 68%

“…The phenomenon can reveal itself through the emergence of unique macroscopic properties, as reported recently in a study of poly-lactide-b-poly(-2-isopropyl-2-oxazoline) micelles in water. 49 In the course of this study of azopyridine-endmodified PNIPAM dispersed in neutral aqueous media, we recorded an exceptionally fast cis-to-trans thermal relaxation of the chromophore attributed to the formation of H-bonds between AzPy and PNIPAM chains. The "flower micelle" morphology typical of α,ω-hydrophobically modified PNI-PAMs cannot account for this observation.…”

Section: Discussionmentioning

confidence: 98%

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pH-Dependent Morphology and Photoresponse of Azopyridine-Terminated Poly(N-isopropylacrylamide) Nanoparticles in Water

et al. 2019

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A series of azopyridine-terminated poly( N -isopropylacrylamide)s (PNIPAM) (C12-PN-AzPy) (∼5000 < M w < 20 000 g mol –1 , polydispersity index 1.25 or less) were prepared by reversible addition–fragmentation chain-transfer polymerization of NIPAM in the presence of a chain-transfer agent that contains an AzPy group and an n -dodecyl chain. In cold water, the polymers form nanoparticles (5.9 nm < R h < 10.9 nm) that were characterized by light scattering (LS), 1 H NMR diffusion experiments, and high-resolution transmission electron microscopy. We monitored the pH-dependent photoisomerization of C12-PN-AzPy nanoparticles by steady-state and time-resolved UV–vis absorption spectroscopy. Azopyridine is known to undergo a very fast cis-to-trans thermal relaxation when the azopyridine nitrogen is quaternized or bound to a hydrogen bond donor. The cis-to-trans thermal relaxation of the AzPy chromophore in an acidic nanoparticle suspension is very fast with a half-life τ = 2.3 ms at pH 3.0. It slows down slightly for nanoparticles in neutral water (τ = 0.96 s, pH 7.0), and it is very slow for AzPy-PNIPAM particles in alkaline medium (τ > 3600 s, pH 10). The pH-dependent dynamics of the cis-to-trans dark relaxation, supported by Fourier transform infrared spectroscopy, 1 H NMR spectroscopy, and LS analysis, suggest that in acidic medium, the nanoparticles consist of a core of assembled C12 chains surrounded by a shell of hydrated PNIPAM chains with the AzPy + end groups preferentially located near the particle/water interface. In neutral medium, the shell surrounding the core contains AzPy groups H-bonded to the amide hydrogen of the PNIPAM chain repeat units. At pH 10.0, the amide hydrogen binds preferentially to the hydroxide anions. The AzPy groups reside preferentially in the vicinity of the C12 core of the nanoparticles. The morphology of the nanoparticles results from the competition between the segregation of the hydrophobic and hydrophilic components and weak attractive interactions, such as H-bonds between the AzPy groups and the amide hydrogen of the PNIPAM repeat units.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 98%

pH-Dependent Morphology and Photoresponse of Azopyridine-Terminated Poly(N-isopropylacrylamide) Nanoparticles in Water

et al. 2019

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“…Therefore, PEG can significantly prolong the blood circulation time of polymeric NPs . Numerous synthetic di-block copolymers with different combinations of polymer blocks have been explored to make polymeric nanoparticles with advanced properties such as good reproducibility, circulation time, cargo loading, stability, degradability, biocompatibility, and control of NP size and cellular uptake. ,− …”

Section: Different Types Of Nanoparticles By Nanoprecipitationmentioning

confidence: 99%

Formulation of Nanoparticles Using Mixing-Induced Nanoprecipitation for Drug Delivery

Liu

Yang

Zou

et al. 2019

Ind. Eng. Chem. Res.

136

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Significant efforts have been made to fabricate drug-loaded nanoparticles for drug delivery. Nanoprecipitation is a simple and versatile method for making various types of polymer nanoparticles with well-controlled particle size, size distribution, and surface properties. This review presents a critical overview of three different widely used nanoprecipitation techniques, namely, traditional nanoprecipitation in bulk solutions, flash nanoprecipitation, and microfluidic-based nanoprecipitation. The review starts with the comparison of these three different nanoprecipitation methods summarizing their key characteristics, advantages, and disadvantages. Then, different types of nanoparticles synthesized using nanoprecipitation are presented including di-block copolymer nanoparticles and natural polymer nanoparticles. A special focus is placed on comparing different drug-loaded polymer nanoparticles prepared using different nanoprecipitation approaches including their synthesis methods, drug loading, encapsulation efficiency, nanoparticle properties (e.g., size, PDI, etc.), and stability. Finally, the principle of forming nanoparticles with well-controlled properties is discussed to fundamentally understand the intricate interplay between mixing, supersaturation, nucleation, and particle growth, aiming to provide a general guideline for making drug-loaded nanoparticles based on nanoprecipitation.

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“…A similar strategy was employed by Winnik's group to design a unique molecular structure for fabrication of thermo‐responsive nanoparticles. [ 25 ] They prepared a novel diblock copolymer with one segment being the hydrophilic and thermosensitive poly(2‐isopropyl‐2‐oxazoline) (PiPO x ) and the other segment being the hydrophobic poly(L‐lactide) (PLA). After gentle solvent exchange from THF to water, the polymer solution was heated to remove the residual good solvent THF.…”

Section: Approaches To Nanoparticles With Ordered Structuresmentioning

confidence: 99%

Synthetic advances of internally nanostructured polymer particles: From and beyond block copolymer

et al. 2020

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Polymer particles with internal nanostructures for versatile applications in many fields have attracted widespread attention. Among the diverse synthetic strategies toward polymer particles, polymer assembly in solution or melt is one of the most powerful methods to fabricate various hierarchically nanostructured materials in different length scales. In the review, we summarized the recent advances of several significant synthetic strategies of polymer particles with unique internal structures: (1) the principle of solvent exchange-induced either self-organized or scalable flash nanoprecipitation, (2) emulsion-solvent evaporation by engineering the interfacial interaction between the emulsion droplet and medium, (3) template-assisted method, and (4) polymerization-induced assembly method. In each part, we systematically describe key factors such as interfacial relationship, solvent properties, and chemical nature of polymer that dictate the formation and evolution of their morphology. Finally, we discussed remaining issues of nanostructured polymer assemblies and their potential for future applications.

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Poly(2-isopropyl-2-oxazoline)-b-poly(lactide) (PiPOx-b-PLA) Nanoparticles in Water: Interblock van der Waals Attraction Opposes Amphiphilic Phase Separation

Cited by 8 publications

References 38 publications

pH-Dependent Morphology and Photoresponse of Azopyridine-Terminated Poly(N-isopropylacrylamide) Nanoparticles in Water

pH-Dependent Morphology and Photoresponse of Azopyridine-Terminated Poly(N-isopropylacrylamide) Nanoparticles in Water

Formulation of Nanoparticles Using Mixing-Induced Nanoprecipitation for Drug Delivery

Synthetic advances of internally nanostructured polymer particles: From and beyond block copolymer

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