New water-soluble block copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2) MA), oligo(ethylene glycol) methacrylate (OEGMA), and N-(3-(dimethylamino) propyl) methacrylamide (DMAPMA) (poly(OEGMA-co-MEO(2) MA)-b-poly(DMAPMA)) were prepared via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. Selective quaternization of poly(DMAPMA) block gives poly(OEGMA-co-MEO(2) MA)-b-poly((3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropane sulfonate)-co-N-(3-(dimethylamino) propyl) methacrylamide), such block copolymer exhibits double thermo-responsive behavior in water, poly(MEO(2) MA-co-OEGMA) block shows a lower critical solution temperature (LCST), and poly((3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropane sulfonate)-co-N-(3-(dimethylamino) propyl) methacrylamide) block shows a upper critical solution temperature (UCST). Both of LCST and UCST can be controlled: LCST could be tuned by the fraction of OEGMA units in poly(OEGMA-co-MEO(2) MA), and UCST was found to be dependent on the degree of quaternization (DQ).
In order to develop the high‐temperature‐released pyrrole aroma, two novel flavors precursors of methyl 2‐methyl‐5‐(((2‐methylbutanoyl)oxy)methyl)‐1‐propyl‐1H‐pyrrole‐3‐carboxylate and methyl 2‐methyl‐5‐(((2‐methylbutanoyl)oxy)methyl)‐1‐propyl‐1H‐pyrrole‐3‐carboxylate were synthesized using glucosamine hydrochloride and methyl acetoacetate as raw materials through cyclization, oxidation, alkylation, reduction, and esterification. The target compounds were characterized by nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (IR) and high‐resolution mass spectrometry (HRMS). Thermogravimetry (TG), differential scanning calorimeter (DSC) and the pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS) methods were used to analyze the heating‐stability of the target compounds, and the pyrolysis mechanism was inferred. Py‐GC/MS results indicated that some fragrance compounds were formed during thermal degradation such as 2‐methylbutyric acid, 2‐methylbutyrate, alkylpyrroles, and benzoic acid, which were important aroma components or flavor additives. This provided a theoretical reference for the application of pyrrole ester in cigarette and heat‐processed food flavoring.
A new pterocarpan, named davidicarpan A (1), together with 9 known flavonoids, including 3 pterocarpans (2-4) and 6 isoflavones (5-10), were isolated from the flowers of Sophora davidii (France.) Pavol. Their structures were confirmed by high-resolution electrospray ionization-mass spectrometry, one-dimensional (1D) and 2D nuclear magnetic resonance spectroscopy, and comparison with reported literature values. Compounds 1 and 4 exhibited anti-tobacco mosaic virus (anti-TMV) activities with inhibition rates of 27.4% and 26.2%, which was higher than that of the positive control, ningnamycin.
Abstract. In this investigation, a novel temperature-pH responsive copolymer was prepared by the radical copolymerization between 2-hydroxypropyl acrylate (HPA) and aminoethyl methacrylate hydrochloric salt (AMHS). The molecular structure of the corresponding copolymer has been confirmed by 1 H NMR and FTIR measurements. The results indicated that the lower critical solution temperature (LCST) of the resulting copolymer has shown a considerable dependence on the monomer ratio and pH value in the medium. When the molar ratio of HPA to AMHS unit on polymer chain was fixed at 1.56, 2.25, and 3.01, the LCSTs of copolymers were observed at 36.5, 28.2 and 17.8°C, respectively. For the effect of additive salts, the LCST change of the copolymer was affected by both cations and anions in the following order of Al(NO3)3 > KNO3 > Mg(NO3)2 > NaNO3 and KCl ≈ KSCN > KBr > KNO3 > KI. The copolymer seems to be useful as a candidate for the controlled-drug release carrier by pH and temperature external stimuli.
Polystyrene-based polyHIPE (polymerized high internal phase emulsion) materials were prepared by the copolymerization of styrene and divinylbenzene in the continuous phase of a HIPE. The resultant polyHIPE materials were found to have an open-cellular morphology and high porosity, and the polyHIPE structure could be well adjusted by varying the water/oil (W/O) ratio and the amount of emulsifier in the HIPE. Cell culture results showed that the resultant polyHIPE materials, which exhibited larger voids and connected windows as well as high porosity, could promote cell proliferation on the 3D scaffold. A 3D cell cytotoxicity evaluation system was constructed with the polystyrene-based polyHIPE materials as scaffolds and the cigarette smoke cytotoxicity was evaluated. Results showed that the smoke cytotoxicity against A549 cells is much lower in the 3D cell platform compared to the traditional 2D system, showing the great potential of the polyHIPE scaffolds for 3D cell culture and the cytotoxic evaluation of cigarette smoke.
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