Jae-Hun Yang

Drug-inorganic-polymer nanohybrid for transdermal delivery.

For transdermal drug delivery, we prepared a drug-inorganic nanohybrid (FB-LDH) by intercalating a transdermal model drug, flurbiprofen (FB), into the layered double hydroxides (LDHs) via coprecipitation reaction. The X-ray diffraction patterns and FT-IR spectra of the FB-LDH indicated that the FB molecules were successfully intercalated via electrostatic interaction within the LDH lattices. The in vitro drug release revealed that the Eudragit(®) S-100 in release media could facilitate the drug out-diffusion by effectively replacing the intercalated drug and also enlarging the lattice spacing of the FB-LDH. In this work, a hydrophobic gel suspension of the FB-LDH was suggested as a transdermal controlled delivery formulation, where the suspensions were mixed with varying amounts of Eudragit(®) S-100 aqueous solution. The Frantz diffusion cell experiments using mouse full-skins showed that a lag time and steady-state flux of the drug could be controlled from 12.8h and 3.28μgcm(-2)h(-1) to less than 1h and 14.57μgcm(-2)h(-1), respectively, by increasing the mass fraction of Eudragit(®) S-100 solution in gel suspensions from 0% to 20% (w/w), respectively. Therefore, we conclude gel formulation of the FB-LDH have a potential for transdermal controlled drug delivery.

TiO2-pillared clays with well-ordered porous structure and excellent photocatalytic activity

TiO2-pillared clays with well-ordered porous structures are successfully prepared via incorporating TiO2 nanosol particles into the clays, where empty octahedral sites are partially modified with divalent metal ions such as Mg2+ and Fe2+. The prepared TiO2-pillared mica exhibits excellent photocatalytic activity, which can be controlled by tuning the optical transparency of clay support rather than the specific surface area of the hybrid catalysts.

Influence of anionic surface modifiers on the thermal stability and mechanical properties of layered double hydroxide/polypropylene nanocomposites

Organo-layered double hydroxide/polypropylene (LDH/PP) nanocomposites were successfully synthesized via a solution blending method. As an attempt to improve the compatibility with hydrophobic PP, the LDH surface was modified by the incorporation of various anionic surfactants via electrostatic interaction with LDH cationic layers. Surfactants were selected by considering the aliphatic carbon chain length (laurate, palmitate, stearate and dodecyl sulfate) and anionic functional groups (–COO−, –OPO32−, and –OSO3−) with the purpose of optimizing the homogeneous dispersion in the PP matrix. In PP nanocomposites containing LDH modified with alkyl carboxylate, the (00l) X-ray diffraction (XRD) peaks originating from organo-LDH were not observed, indicating that organo-LDH layers were fully exfoliated and homogeneously dispersed within the PP matrix, which were also confirmed by cross-sectional TEM analysis. However, PP nanocomposites containing LDH modified with dodecyl sulfate and lauryl phosphate showed broad (00l) XRD peaks, indicating that organo-LDH was partially exfoliated. According to the thermogravimetric analysis, the thermal stability (T0.5) of organo-LDH/PP nanocomposites was significantly improved by 37–60 K, depending on the type and loading content of organo-LDH compared to that of pristine PP. PP nanocomposites containing well-dispersed organo-LDH showed substantial enhancement of the elastic modulus with little decrease of tensile strength. These results are due to the increased interface volume fraction provided by the exfoliated LDH nanosheets.

2D Inorganic-Antimalarial Drug-Polymer Hybrid with pH-Responsive Solubility.

Artesunic acid (ASH), an antimalarial drug, has low oral bioavailability due to its low aqueous solubility. To overcome this problem, artesunate (AS) was intercalated into zinc basic salt (ZBS) via co-precipitation. AS was immobilized with a tilted double layer arrangement, which was also confirmed by XRD and 1-D electron density mapping. In order to decrease the release rate of AS under gastrointestinal conditions and to simultaneously increase the release rate of AS under intestinal conditions, ZBS-AS was coated with EUDRAGIT L100 (ZBS-AS-L100). Finally, we performed an in-vivo pharmacokinetic study to compare the oral bioavailability of AS of ZBS-AS-L100 with that of ASH. Surprisingly, it was found that the former is 5.5 times greater than the latter due to an enhanced solubility of AS thanks to the ternary hybridization with ZBS and EUDRAGIT L100. Therefore, the present ZBS-AS-L100 system has a great potential as a novel antimalarial drug formulation with pH selectivity and enhanced bioavailability.

Clay-organic intumescent hybrid system for the synergetic flammability of polymer nanocomposites

A polyethylene vinyl acetic acid (EVA) nanocomposite comprising of an intumescent agent that incorporates ammonium phosphate monobasic, mono-pentaerythritol, and melamine with a cationic nanoclay was set up through solution blending and melt blending to assess the fire retardancy utilizing a cone calorimeter. The results demonstrated that there was a significant reduction in the peak heat release rate of 70% contrasted with pure EVA. The fire retardancy of the clay-organic intumescent mixture framework composite was more successful than a same amount of additional nanoclay and intumescent agent. To check these outcomes, the residues of cone calorimeter samples were assessed alongside clay d-spacing changes amid utilization.