Enhanced Therapeutic Efficacy of Lipophilic Amphotericin B Against Candida albicans with Amphiphilic Poly(N-isopropylacrylamide) Nanogels

Muhammad Qasim,박한수,Phornsawat Baipaywad,Nopphadol Udomluck,나도균 한국고분자학회 2014 Macromolecular Research Vol.22 No.10

Candidiasis is a disease with skin rashes caused by the infectious fungus, Candida albicans, and can bepotentially life-threatening, especially in immunodeficient patients. Amphotericin B (AmB) is a potent antifungalagent with a broad spectrum to treat Candidiasis, but its inherent low solubility and limited skin bioavailability haveprevented its wider clinical use. In this study, we developed poly(N-isopropylacrylamide) (pNIPAM)-based nanogels as aversatile carrier to enhance AmB solubility and its efficacy. pNIPAM nanogels enhanced the solubility of AmB by 1.6-foldversus AmB alone. Accordingly, pNIPAM markedly improved the minimal fungicidal concentration (MFC) of AmBby 8 folds from 3.91 to 0.49 μg/mL. We also attached NH2 group to the pNIPAM nanogel to increase surface chargesand investigated its effect on AmB antifungal activity. pNIPAM-NH2 has comparable activity in solid culture to pNIPAM,but 2-fold higher antifungal activity in liquid culture. Our pNIPAM and pNIPAM-NH2 nanogels may be usefulas drug delivery agents for the treatment of local antifungal infections by AmB in solid and liquid environments,such as on skin and in blood, with high efficacy and sustainability.

Dual Stimuli-Triggered Nanogels in Response to Temperature and pH Changes for Controlled Drug Release

Kim, Yun Kyoung,Kim, Eun-Joong,Lim, Jae Hyun,Cho, Heui Kyoung,Hong, Woo Jin,Jeon, Hyang Hwa,Chung, Bong Geun Springer US 2019 NANOSCALE RESEARCH LETTERS Vol.14 No.1

<P>Poly-<I>N</I>-isopropyl acrylamide (PNIPAM) nanogels have been modified with different acrylic acid (AAc) contents for the efficient control of lower critical solution temperature (LCST). In this study, PNIPAM-co-AAc nanogels nanogels showed two volume phase transitions in comparison with PNIPAM. The transition temperature of PNIPAM nanogels was increased with AAc contents. The controlled drug release performance of PNIPAM-co-AAc nanogels loaded with β-lapachone was attributed to the AAc content ratio and was efficiently triggered in response to temperature and pH. Moreover, a colorimetric cell proliferation assay and direct fluorescence-based live/dead staining were used to confirm the concurrence on drug release profiles. Finally, PNIPAM-co-AAc20 showed a relatively low level of drug release in the range of acidic to neutral pH at body temperature, while maximizing drug release at basic pH. Therefore, we demonstrated that the PNIPAM-based nanogel with the temperature- and pH-responsive features could be a promising nanocarrier for potential intestine-specific drug delivery.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s11671-019-2909-y) contains supplementary material, which is available to authorized users.</P>

Experimental evaluation of RAFT-based Poly(<i>N</i>-isopropylacrylamide) (PNIPAM) kinetic hydrate inhibitors

Park, Juwoon,Kim, Hyunho,da Silveira, Kelly Cristine,Sheng, Qi,Postma, Almar,Wood, Colin D.,Seo, Yutaek Elsevier 2019 Fuel Vol.235 No.-

<P><B>Abstract</B></P> <P>As the oil and gas industry produces hydrocarbons from deeper waters and colder regions the issue of hydrate formation becomes more serious. As a result, hydrate inhibition has focused on kinetic hydrate inhibitors (KHI) and anti-agglomerants (AA) as an alternative to the existing approaches which involves injecting vast quantities of thermodynamic inhibitors. In this research, we evaluated the effect of different architectures (linear and branched) of poly(<I>N</I>-isopropylacrylamide) (PNIPAM) polymers synthesized using reversible addition−fragmentation chain-transfer (RAFT) polymerization. Unlike non-reversible deactivation radical polymerisation (RDRP) synthetic routes this generates accurately controlled KHI candidates with target molecular weight, narrow molecular weight distributions and controlled architecture, so that the effect on hydrate inhibition can be more accurately assessed. The RAFT-based polymers (linear and branched) were compared to a commercially available linear PNIPAM synthesized <I>via</I> non-RDRP radical polymerization and control groups (pure water, PVP, and Luvicap). The hydrate experiments were performed in a high pressure autoclave with continuous cooling under different cooling rates (0.25 K/min, 0.033 K/min, and 0.017 K/min). In addition, a cold restart was simulated using constant subcooling. The results regarding subcooling temperature, onset time, and hydrate fraction with resistance-to-flow were compared to known KHIs. These revealed that a linear PNIPAM-MacroRAFT polymer delayed the hydrate nucleation with similar performance to known KHIs (eg., PVP and Luvicap). However, a branched polymer showed the best performance in terms of hydrate fraction and resistance-to-flow among all of the systems tested in this study. These data provide valuable information regarding linear and branched PNIPAM-MacroRAFT polymers by demonstrating their ability to delay hydrate formation but also in preventing hydrate agglomeration. These findings confirm that polymer architecture can effect hydrate inhibition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RAFT polymerization was applied to generate architecturally defined KHIs. </LI> <LI> Linear and branched PNIPAM were fully evaluated while varying the cooling rate. </LI> <LI> Our results suggest a possible new mechanism for managing hydrate formation with a branched PNIPAM. </LI> <LI> This study provided a better understanding of the architecture-property effect on hydrate prevention. </LI> </UL> </P>

Preparation of monodispersed PNIPAm/silica composites and characterization of their thermal behaviors

Yong-Geun Lee,Chang-Yong Park,Kyung-Ho Song,Sung-Soo Kim,오성근 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.2

Two types of thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-silica organic/inorganic hybrid particles were successfully prepared in aqueous solution through a facile synthetic process. Silane coupler of vinyl organic groups connects the PNIPAm to silica. First, hybrid spheres were prepared by grafting PNIPAm polymers to VTMS (vinyl trimethoxysilane) silica spheres. The thickness of polymer shell on the silica surfaces could be easily controlled by varying the concentrations of NIPAm monomer. Second, another type of hybrid particle was fabricated by encapsulating PNIPAm polymer with silica materials. The PNIPAm polymers were completely encapsulated by silica shell. The morphologies and shell thickness were characterized through SEM and TEM. The variations of phase transition temperature of PNIPAm were measured using DSC.

Preparation of monodispersed PNIPAm/silica composites and characterization of their thermal behaviors

Lee, Yong-Geun,Park, Chang-Yong,Song, Kyung-Ho,Kim, Sung-Soo,Oh, Seong-Geun Elsevier 2012 Journal of industrial and engineering chemistry Vol.18 No.2

<P><B>Abstract</B></P><P>Two types of thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-silica organic/inorganic hybrid particles were successfully prepared in aqueous solution through a facile synthetic process. Silane coupler of vinyl organic groups connects the PNIPAm to silica. First, hybrid spheres were prepared by grafting PNIPAm polymers to VTMS (vinyl trimethoxysilane) silica spheres. The thickness of polymer shell on the silica surfaces could be easily controlled by varying the concentrations of NIPAm monomer. Second, another type of hybrid particle was fabricated by encapsulating PNIPAm polymer with silica materials. The PNIPAm polymers were completely encapsulated by silica shell. The morphologies and shell thickness were characterized through SEM and TEM. The variations of phase transition temperature of PNIPAm were measured using DSC.</P>

Facile Synthesis of Thermo-responsive TiO2/PNIPAM Composite with Switchable Photocatalytic Performance

Yinli Duan,Jing Ma,Jiao Liu,Liang-Sheng Qiang,Juanqin Xue 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

In this paper, a facile and efficient method was performed to prepare the thermo-responsive Poly(Nisopropylacrylamide)/TiO2 (TiO2/PNIPAM) with the dispersing of TiO2 nanoparticles into PNIPAM. The structures ofnanoparticles and the grafted polymer were confirmed by X-ray diffraction (XRD), Raman spectra, Fourier transforminfrared spectra (FT-IR) and Dynamic Light Scattering (DLS). The interactions between the two components were studied byX-ray photoelectron spectroscopy (XPS), and the morphology of TiO2/PNIPAM was observed by scanning electronmicroscopy (SEM). The results showed that TiO2 exhibited homogeneous dispersion, without sacrificing the properties ofTiO2. Furthermore, The composite was used to photocatalytic degradation of Methylene blue (MB). The highest MB removalefficiency is 86.3 %. The photocatalytic activities above or below the lower critical solution temperature (LCST) of PNIPAMwas also investigated. The experiment results show that the existence of PNIPAM contributed not only the thermo-responsiveabilities to TiO2, but also the enhanced photocatalytic activities to TiO2. In addition, the corresponding mechanism ofenhanced photocatalytic activity was proposed. The results manifest that the well-designed TiO2/PNIPAM is a promisingcandidate in wastewater treatment application.

Temperature-responsive swelling behavior of hydrogel/silicone composites

김준석,안수영,이종휘 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

The composites of hydrogel and silicone could be a solution for the defects of each other, mechanical properties and hydrophobicity. With introduction of responsive material, the composites could find future applications in the biomedical fields or soft robotics. In here, temperature-responsive composites with well mixed structures of Poly(N-isopropylacrylamide) (PNIPAM) hydrogel and polydimethylsiloxane (PDMS) were fabricated by directional melt crystallization to obtain 3-D continuous porous PNIPAM and infiltrating PDMS into the pores of hydrogel. When swelling, PNIPAM phase became obvious, distinctly different from PDMS, which could not be found at the dry state. Volume transition of composites became faster than that of PNIPAM. Especially, significant bending moment of anisometric layered composites was found due to the lower critical solution temperature (LCST) of PNIPAM. This class of materials could be an interesting bridge between hydrophobic and hydrophilic materials.

Indentation and temperature response of liquid metal/hydrogel composites

Sooyeon Kim,이종휘 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.110 No.-

The volume transition of thermo-responsive hydrogels has been investigated for various applicationssuch as soft actuators, sensors, drug delivery systems, and bioelectronics. Nonetheless, issues such aspoor mechanical properties, slow transition rates, and limited volume change windows have promptedthe development of hydrogel composites. Gallium (Ga), a liquid metal, is combined with poly(Nisopropylacrylamide) (PNIPAm) with varying composite structures in this work. Ga’s melting point isclose to PNIPAm’s volume transition temperature. The introduction of Ga particles into PNIPAm improvesboth the indentation resistance and the transition rate of the hydrogel. Microchannel structure can furtherimprove the transition rate by increasing the water diffusion rate. The relatively fast thermal conductionof the Ga phase in anisotropic composites causes fast deswelling of Ga-rich regions, resultingin unique double bending behavior. The double bending behavior was utilized to hold irregularly shapedobjects firmly. These results offer a useful design strategy of composites for the development of novelresponsive smart systems.

Palladium Nanoparticles on Thermoresponsive Hydrogels and their Application as Recyclable Suzuki–Miyaura Coupling Reaction Catalysts in Water

Hong, Myeng Chan,Choi, Myung Chan,Chang, Young Wook,Lee, Yongwoo,Kim, Jongsik,Rhee, Hakjune WILEY‐VCH Verlag 2012 Advanced Synthesis & Catalysis Vol.354 No.7

<P><B>Abstract</B></P><P>Palladium nanoparticles were immobilized on PNIPAM:4‐VP hydrogels. The resultant püalladium catalysts showed high activities for Suzuki–Miyaura coupling reactions in water. The recyclability of the catalysts was improved by using 4‐VP as a co‐monomer in the hydrogels due to reduced Pd leaching during the reactions.</P>

Novel stimuli-responsive hydrogel composites based on silicone and PNIPAM

김준석,안수영,이종휘 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels and polydimethylsiloxane (PDMS) have completely different wetting properties against water. Whereas PDMS is extremely hydrophobic, PNIPAM is relatively hydrophilic. And the hydrophilicity of PNIPAM depends on temperature,i.e., more hydrophobic above and more hydrophilic below their low critical solution temperature (LCST). Due to quite different surface energies, the preparation of composites based on the two extreme polymers, hydrophilic and hydrophobic polymers, has been difficult.In this study, composites of the two polymers were developed as stimuli-responsive materials from PNIPAM hydrogels of through-thickness pores prepared by directional melt crystallization of solvent. The structures of the two polymers in composites were identified by a scanning electron microscope (SEM). After swelling, the PNIPAM phase becomes distinctly swollen, which was obvious under SEM. The contact angle of water droplet depends on the surface compositions of the two polymers. With swelling in water, significant bending moment of composite films developed, which in turn depends on temperature.