Controlled
modification in the structure and properties of three-dimensional
(3D) printed polymers, as in the broader context of cross-linked polymer
networks, in response to an external stimulus has been of great importance
to meet the demands of advanced applications and environmental sustainability
concerns. In this study, a dynamic covalent di(meth)acrylate cross-linker
containing a reversible addition–fragmentation chain transfer
(RAFT) trithiocarbonate (TTC) functionality was synthesized and used
for the formation of living photoexpandable/transformable polymer
networks (PET-PNs). The network-bound TTC functionalities were activated
in a postsynthesis stage via a visible light-controlled photoredox-catalyzed
RAFT polymerization, enabling monomer addition into the existing scaffolds.
This approach allowed controllable and successive postsynthesis photogrowth,
photofunctionalization, and/or photowelding reactions. The expandable
RAFT-capable TTC cross-linker (TTC-XL) was also exploited to manufacture
living 3D materials via a layer-by-layer photopolymerization process
facilitated by a modified digital light processing (DLP) 3D printer.
The 3D printed materials were also capable of undergoing successive
postprinting reactions (e.g. functionalization) via a photoredox-catalyzed
RAFT process under a red light-emitting diode (LED) light irradiation.
From the viewpoint of material sustainability and recyclability, this
study is a great step forward and it will open up additional possibilities
in the field of 3D printing for the fabrication of advanced functional
materials.
Peroxisome proliferator-activated receptor γ (PPARγ) is recognized as a key regulator of insulin resistance. In this study, we searched for novel PPARγ agonists in a library of structurally diverse organic compounds and determined that podophyllotoxin exhibits partial agonist activity toward PPARγ. Eight novel podophyllotoxin-like derivatives were synthesized and assayed for toxicity and functional activity toward PPARγ to reduce the possible systemic toxic effects of podophyllotoxin and to maintain partial agonist activity toward PPARγ. Cell-based transactivation assays showed that compounds (E)-3-(hydroxy(3,4,5-trimethoxyphenyl)methyl)-4-(4(trifluoromethyl)styryl)dihydrofuran-2(3H)-one (3a) and (E)-4-(3-acetylstyryl)-3-(hydroxyl (3,4,5-trimethoxyphenyl)methyl)dihydrofuran-2(3H)-one (3f) exhibited partial agonist activity. An experiment using human hepatocarcinoma cells (HepG2) that were induced to become an insulin-resistant model showed that compounds 3a and 3f improved insulin sensitivity and glucose consumption. In addition, compounds 3a and 3f significantly improved hyperglycemia and insulin resistance in high-fat diet-fed streptozotocin (HFD-STZ)-induced type 2 diabetic rats at a dose of 15 mg/kg/day administered orally for 45 days, without significant weight gain. Cell toxicity testing also showed that compounds 3a and 3f exhibited weaker toxicity than pioglitazone. These findings suggested that compounds 3a and 3f improved insulin resistance in vivo and in vitro and that the compounds exhibited potential for the treatment of type 2 diabetes mellitus.
A series of metalized C‐PIM‐M (M = Na+, Mg2+, Al3+, PIMs = polymers of intrinsic microporosity) materials were prepared from a carboxyl‐functionalized PIM (C‐PIMs). The C‐PIM‐Na exhibited a high CO2 adsorption capacity of 2.44 mmol/g and extreme low CH4 uptake of 0.28 mmol/g at 273 K and 101 kPa among three metallated PIMs. It showed remarkably high CO2/CH4 and CO2/N2 selectivities at both 273 and 293 K due to an advantageous pore‐blocking effect of Na+ cation.
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