Thermoresponsive Polypeptoid‐Coated Superparamagnetic Iron Oxide Nanoparticles by Surface‐Initiated Polymerization

Kurzhals, Steffen; Pretzner, Barbara; Reimhult, Erik; Zirbs, Ronald

doi:10.1002/macp.201700116

Cited by 14 publications

(21 citation statements)

References 46 publications

(94 reference statements)

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“…Analogously, the PEtOx-block exhibits a drop of ∼14 and ∼11 °C for the inner and outer blocks, respectively. This reduction in transition temperature upon grafting is in agreement with reports on thermoresponsive polymer brushes such as polyoxazolines, 13 , 14 polypeptoids, 4 and poly(poly(ethylene glycol) methacrylate) 15 that all have shown a significant reduction in critical solution temperature upon grafting. A straightforward, phenomenological interpretation of this observation is that the highly hydrated polymers are above the concentration corresponding to the LCST in the phase diagram already as free coils; when they are effectively forced to even higher local concentration in a brushlike shell grafted on a nanoparticle, the critical solution temperature will drop in the phase diagram.…”

Section: Resultssupporting

confidence: 90%

“… 13 In that particular study, incorporation of ethyl-oxazoline units led to a significant reduction in transition enthalpy compared to a pure poly(2-isopropyloxazoline) (PIPOx) brush and to even stronger reduction compared to that for free polymers. 13 Interestingly, although grafting of PNIPAM had little effect on the transition temperature, 3 , 12 a reduction was observed for other thermoresponsive polymer brushes such as polyoxazolines, 13 , 14 polypeptoids, 4 and poly(poly(ethylene glycol) methacrylate) 15 compared to their free polymer analogues.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Grafted Block Copolymer Structure on Thermoresponsiveness of Superparamagnetic Core–Shell Nanoparticles

et al. 2017

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The morphology and topology of thermoresponsive polymers have a strong impact on their responsive properties. Grafting onto spherical particles has been shown to reduce responsiveness and transition temperatures; grafting of block copolymers has shown that switchable or retained wettability of a surface or particle during desolvation of one block can take place. Here, doubly thermoresponsive block copolymers were grafted onto spherical, monodisperse, and superparamagnetic iron oxide nanoparticles to investigate the effect of thermal desolvation on spherical brushes of block copolymers. By inverting the block order, the influence of core proximity on the responsive properties of the individual blocks could be studied as well as their relative influence on the nanoparticle colloidal stability. The inner block was shown to experience a stronger reduction in transition temperature and transition enthalpy compared to the outer block. Still, the outer block also experiences a significant reduction in responsiveness due to the restricted environment in the nanoparticle shell compared to that of the free polymer state. The demonstrated pronounced distance dependence importantly implies the possibility, but also the necessity, to radially tailor polymer hydration transitions for applications such as drug delivery, hyperthermia, and biotechnological separation for which thermally responsive nanoparticles are being developed.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Influence of Grafted Block Copolymer Structure on Thermoresponsiveness of Superparamagnetic Core–Shell Nanoparticles

et al. 2017

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“…However, aggregated particles with interacting cores produce a magnetic moment sufficiently high for extraction by a fixed magnet that can be built into biotechnological devices for separation. Using nanoparticles grafted with PNiPAAm, 49 polypeptoid (polysarcosin), 42 and PiPrOxA 29 brush, we showed that heating the nanoparticle dispersion to above the CFT could be used to extract superparamagnetic core–shell nanoparticles (Figure 8A). It was also shown that nanoparticles with dense polymer brush shells can spontaneously redisperse within minutes or redisperse by just providing a light shake.…”

Section: Magnetothermal Reversible Aggregationmentioning

confidence: 99%

Design Principles for Thermoresponsive Core–Shell Nanoparticles: Controlling Thermal Transitions by Brush Morphology

2019

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In this feature article, we summarize our recent work on understanding and controlling the thermal behavior of nanoparticles grafted with thermoresponsive polymer shells. Precision synthesis of monodisperse superparamagnetic iron oxide nanocrystals was combined with irreversible dense grafting of nitrodopamide-anchored thermoresponsive polymer chains. We provide an overview of how the dense and stable grafting of biomedically relevant polymers, including poly(ethylene glycol), poly(N-isopropylacrylamide), polysarcosin, and polyoxazolines, can be achieved. This platform has made it possible for us to demonstrate that the polymer brush geometry, as defined by the nanoparticle core and relative polymer brush size, determines the thermal transitions of the polymer brush. We furthermore summarize our work on how the polymer shell transitions and nanoparticle aggregation can be tuned. With the independent variation of the core and the shell, we can optimize and precisely control the thermally controlled solubility of our system. Finally, our feature article gives examples relevant to current and future applications. We show how the thermal response of the shell influences the nanoparticle performance in biological fluids and interactions with proteins and cells, also under purely magnetic actuation of the nanoparticles through the superparamagnetic iron oxide core.

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“…The hydrogels show low cytotoxicity towards human adipose-derived stem cells (hASCs) and exhibit bioactivity in modulating the chondrogenesis biomarker gene expression of hASCs, which indicate the potential utilization of the polypeptoid hydrogel as tissue engineering material [ 57 ]. The monodisperse, superparamagnetic iron oxide nanoparticles (SPION) modified with a thermoresponsive polypeptoid poly( N -methylglyine)- ran -poly( N -butylglycine) (PNMG- r -PNBG) brush was prepared via controlled surface-initiated polymerization of N -substituted NCAs [ 85 ]. The prepared SPION exhibiting excellent biocompatibility, stability, and high functionality can be used in many applications such as magnetic molecular extraction and magnetic resonance imaging.…”

Section: Applicationsmentioning

confidence: 99%

Thermoresponsive Polypeptoids

Liu

Sun

2020

Polymers

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Stimuli-responsive polymers have been widely studied in many applications such as biomedicine, nanotechnology, and catalysis. Temperature is one of the most commonly used external triggers, which can be highly controlled with excellent reversibility. Thermoresponsive polymers exhibiting a reversible phase transition in a controlled manner to temperature are a promising class of smart polymers that have been widely studied. The phase transition behavior can be tuned by polymer architectures, chain-end, and various functional groups. Particularly, thermoresponsive polypeptoid is a type of promising material that has drawn growing interest because of its excellent biocompatibility, biodegradability, and bioactivity. This paper summarizes the recent advances of thermoresponsive polypeptoids, including the synthetic methods and functional groups as well as their applications.

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Thermoresponsive Polypeptoid‐Coated Superparamagnetic Iron Oxide Nanoparticles by Surface‐Initiated Polymerization

Cited by 14 publications

References 46 publications

Influence of Grafted Block Copolymer Structure on Thermoresponsiveness of Superparamagnetic Core–Shell Nanoparticles

Influence of Grafted Block Copolymer Structure on Thermoresponsiveness of Superparamagnetic Core–Shell Nanoparticles

Design Principles for Thermoresponsive Core–Shell Nanoparticles: Controlling Thermal Transitions by Brush Morphology

Thermoresponsive Polypeptoids

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