Geometrical Characteristics of Polyelectrolyte Nanogel Particles and Their Polyelectrolyte Complexes Studied by Dynamic and Static Light Scattering

Kokufuta, Etsuo; Ogawa, Kazuyoshi; Doi, Ryo; Kikuchi, Rie; Farinato, Raymond S.

doi:10.1021/jp070147d

Cited by 34 publications

(24 citation statements)

References 18 publications

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“…The structure parameter, ρ = R g / R h , which reflects the mass distribution of the scattering object, is useful to assess the morphology of self-assembled nanoparticles. 28,34 The R g / R h values of all C12-PN-AzPy nanoparticles in water (10 °C) range from 1.37 to 1.48, a range of values characteristic of random coils and of core/shell particles with a solvated shell. TEM images of dried C12-PN-AzPy suspensions provide further support to the size of the micelles and the formation of core/shell assemblies (Figure 2c,d).…”

Section: Results and Discussionmentioning

confidence: 99%

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: Results and Discussionmentioning

confidence: 99%

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

et al. 2019

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“…The hydrodynamic radius ( R h ) of the polymer in DMF is 164 nm as measured by DLS (shown in Figure 2b). Generally, for nanogels R g /R h > 0.775 is related to significant numbers of dangling chains attached to the nanogel particle surface 46. Here, R g /R h is 0.97, which indicates the formation of nanogels with dangling arms.…”

Section: Resultsmentioning

confidence: 99%

Disulfide Core Cross‐Linked PEGylated Polypeptide Nanogel Prepared by a One‐Step Ring Opening Copolymerization of N‐Carboxyanhydrides for Drug Delivery

Xing¹,

Lai²,

Ye³

et al. 2011

Macromolecular Bioscience

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A novel disulfide core cross-linked PEGylated polypeptide nanogel has been synthesized by a one-step ring opening copolymerization of γ-benzyl L-glutamate N-carboxyanhydride and L-cystine N-carboxyanhydride using an amino group-terminated poly(ethylene glycol) methyl ether as initiator. Characterization of products confirms the formation of a core cross-linked PEGylated nanogel with disulfide linkages with a size of about 250 nm, and these studies also confirm that this nanogel can easily be broken by glutathione. Cell viability experiments show the good biocompatibility of the as-prepared polymer. Studies relating to loading and controlled release of indomethacin under reduction-sensitive conditions reveal that the nanogel is a good candidate for drug delivery systems.

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“…Dynamic light scattering (DLS) can be used to determine the LCST of thermoresponsive PNIPAAm and derivatives, based on the prediction of interaction behaviors between polymers in the system. Across LCST, the particle sizes of PNIPAAm containing products display an abrupt change from large to small or show a sharp transition from small to large [70][71][72]. The LCST of PNIPAAm homopolymers and copolymers can also be simply measured by cloud point (turbidity) measurements.…”

Section: Volume Phase Transition Temperature/lower Critical Solution mentioning

confidence: 99%

Preparation and Characterization of Thermoresponsive Poly(N-Isopropylacrylamide) for Cell Culture Applications

et al. 2020

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Poly(N-isopropylacrylamide) (PNIPAAm) is a typical thermoresponsive polymer used widely and studied deeply in smart materials, which is attractive and valuable owing to its reversible and remote "on-off" behavior adjusted by temperature variation. PNIPAAm usually exhibits opposite solubility or wettability across lower critical solution temperature (LCST), and it is readily functionalized making it available in extensive applications. Cell culture is one of the most prospective and representative applications. Active attachment and spontaneous detachment of targeted cells are easily tunable by surface wettability changes and volume phase transitions of PNIPAAm modified substrates with respect to ambient temperature. The thermoresponsive culture platforms and matching thermal-liftoff method can effectively substitute for the traditional cell harvesting ways like enzymatic hydrolysis and mechanical scraping, and will improve the stable and high quality of recovered cells. Therefore, the establishment and detection on PNIPAAm based culture systems are of particular importance. This review covers the important developments and recommendations for future work of the preparation and characterization of temperature-responsive substrates based on PNIPAAm and analogues for cell culture applications.

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Geometrical Characteristics of Polyelectrolyte Nanogel Particles and Their Polyelectrolyte Complexes Studied by Dynamic and Static Light Scattering

Cited by 34 publications

References 18 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

Disulfide Core Cross‐Linked PEGylated Polypeptide Nanogel Prepared by a One‐Step Ring Opening Copolymerization of N‐Carboxyanhydrides for Drug Delivery

Preparation and Characterization of Thermoresponsive Poly(N-Isopropylacrylamide) for Cell Culture Applications

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