Investigation of the Formation Process of PNIPAM-Based Ionic Microgels

Chen, Rui; Jin, Xin; Zhu, Xinyuan

doi:10.1021/acsomega.7b01624

Cited by 6 publications

(2 citation statements)

References 20 publications

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“…PNIPAm microgels are synthesized by free-surfactant radical polymerization as detailed in [ 32 ]. We employed two ionic initiators, potassium peroxodisulfate (KPS) and 2,2’-Azobis(2-methylpropionamidine) dihydrochloride (AIBA), because of their proven efficacy in initiating FRP [ 1 , 47 ] and hence in determining the electrophoretic behavior of the final microgels. The two initiators have generally two different initial reaction rates, as reported for other microgel systems [ 48 ].…”

Section: Methodsmentioning

confidence: 99%

The Double-Faced Electrostatic Behavior of PNIPAm Microgels

et al. 2021

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PNIPAm microgels synthesized via free radical polymerization (FRP) are often considered as neutral colloids in aqueous media, although it is well known, since the pioneering works of Pelton and coworkers, that the vanishing electrophoretic mobility characterizing swollen microgels largely increases above the lower critical solution temperature (LCST) of PNIPAm, at which microgels partially collapse. The presence of an electric charge has been attributed to the ionic initiators that are employed when FRP is performed in water and that stay anchored to microgel particles. Combining dynamic light scattering (DLS), electrophoresis, transmission electron microscopy (TEM) and atomic force microscopy (AFM) experiments, we show that collapsed ionic PNIPAm microgels undergo large mobility reversal and reentrant condensation when they are co-suspended with oppositely charged polyelectrolytes (PE) or nanoparticles (NP), while their stability remains unaffected by PE or NP addition at lower temperatures, where microgels are swollen and their charge density is low. Our results highlight a somehow double-faced electrostatic behavior of PNIPAm microgels due to their tunable charge density: they behave as quasi-neutral colloids at temperature below LCST, while they strongly interact with oppositely charged species when they are in their collapsed state. The very similar phenomenology encountered when microgels are surrounded by polylysine chains and silica nanoparticles points to the general character of this twofold behavior of PNIPAm-based colloids in water.

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Section: Methodsmentioning

confidence: 99%

The Double-Faced Electrostatic Behavior of PNIPAm Microgels

et al. 2021

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“…The binding energy of the carbon spectrum for C1s was determined t be 284.7 eV, 286.5 eV, and 287.4 eV for C-C, C-H, and C-N binding, respectively (Figure 4a [18]. The binding energy modes of nitrogen (N1s) were 398.1 eV and 399.4 eV for the C-N an N-H bonds of NIPAm and Am monomer segments, respectively (Figure 4b) [19]. Furthe more, the oxygen element (O1s) peak location for C=O groups of NIPAm units include in the p(NIPAM-co-Am) NG copolymer segments was 532.3 eV (Figure 4c) [20].…”

Section: Instrumental Characterizationsmentioning

confidence: 98%

Dual pH- and Thermo-Sensitive Poly(N-isopropylacrylamide-co-allylamine) Nanogels for Curcumin Delivery: Swelling–Deswelling Behavior and Phase Transition Mechanism

Moorthy

Kim

2023

Gels

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Curcumin (Cur) is a beneficial ingredient with numerous bioactivities. However, due to its low solubility and poor bioavailability, its therapeutic application is limited. In this work, we prepared poly-N-isopropylacrylamide p(NIPAm) and polyallylamine p(Am)-based nanogel (p(NIPAm-co-Am)) NG for a dual pH- and temperature-sensitive copolymer system for drug delivery application. In this copolymer system, the p(NIPAm) segment was incorporated to introduce thermoresponsive behavior and the p(Am) segment was incorporated to introduce drug binding sites (amine groups) in the resulting (p(NIPAm-co-Am)) NG system. Various instrumental characterizations including 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM), zeta potential, and particle size analysis were performed to confirm the copolymer synthesis. Curcumin (Cur), an anticancer bioactive substance, was employed to assess the in vitro drug loading and release performance of the resulting copolymer nanogels system at varied pH levels (pH 7.2, 6.5, and 4.0) and temperatures (25 °C, 37 °C, and 42 °C). The cytocompatibility of the p(NIPAm-co-Am) NG sample was also tested on MDA-MB-231 cells at various sample concentrations. All the study results indicate that the p(NIPAm-co-Am) NG produced might be effective for drug loading and release under pH and temperature dual-stimuli conditions. As a result, the p(NIPAm-co-Am) NG system has the potential to be beneficial in the use of drug delivery applications in cancer therapy.

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Thermo‐sensitive ionic hydrogels synthesis via post quaternization cross‐linking: A highly efficient reusable catalytic thermo‐responsive nanoreactors

Maddahzadeh-Darini

Ghorbanloo

Mori

et al. 2022

Applied Organom Chemis

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Radical polymerization reactions were employed to synthesize thermoresponsive poly(N-isopropylacrylamide-co-1-vinylimidazole), p (NIPAM-co-VIm), hydrogels at room temperature. A postquaternized cross-linking strategy was reported to fabricate thermo-sensitive quaternized-p (NIPAM-co-VIm) ionic hydrogels, Q-p (NIPAm-co-VIm). Combination of methods (highresolution X-ray photoelectron spectroscopy, dynamic light scattering, and atomic absorption spectroscopy) was employed to characterize the composite material. Following the concept of a "green chemistry," the oxidation of alcohols/olefins was carried out in aqueous solution by using nanocomposites, p (NIPAM-co-VIm) and Q-p (NIPAM-co-VIm). It was found that the catalytic activity of the metal nanocomposite can be modulated by the lower critical solution temperature (LCST) of particles. The catalyst showed improved catalytic activity above LCST. Quaternized composites showed higher catalytic activity than unquaternized counterparts, due to their high hydrophobicity, effective interactions between substrates and catalyst, and high flexibility. In addition, we demonstrated that the catalytic activity of the nanocomposites can be tuned by the volume phase transition within the hydrogel by using the catalytic reduction of 4-nitrophenol/nitrobenzene, NP/NB, as the hydrophilic/ hydrophobic substrates model. For 4-NP, with an increase in temperature from 25 C to 35 C (

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Investigation of the Formation Process of PNIPAM-Based Ionic Microgels

Cited by 6 publications

References 20 publications

The Double-Faced Electrostatic Behavior of PNIPAm Microgels

The Double-Faced Electrostatic Behavior of PNIPAm Microgels

Dual pH- and Thermo-Sensitive Poly(N-isopropylacrylamide-co-allylamine) Nanogels for Curcumin Delivery: Swelling–Deswelling Behavior and Phase Transition Mechanism

Thermo‐sensitive ionic hydrogels synthesis via post quaternization cross‐linking: A highly efficient reusable catalytic thermo‐responsive nanoreactors

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