3 research outputs found

    Controlled Mineralization of Calcium Carbonate on the Surface of Nonpolar Organic Fibers

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    Isotactic polypropylene (iPP) fiber, the surface of which is hydrophobic, can modulate the crystallization polymorphs of calcium carbonate (CaCO<sub>3</sub>) at the air/solution interface under mild conditions. The present results provide a novel perspective on controlling the crystallization of biominerals by an insoluble matrix, and they can shed new light on understanding the biomineralization process of CaCO<sub>3</sub> as it occurs in nature

    Double Asynchronous Orthogonal Sample Design Scheme for Probing Intermolecular Interactions

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    This paper introduces a new approach called double asynchronous orthogonal sample design (DAOSD) to probe intermolecular interactions. A specifically designed concentration series is selected according to the mathematical analysis to generate useful 2D correlated spectra. As a result, the interfering portions are completely removed and a pair of complementary sub-2D asynchronous spectra can be obtained. A computer simulation is applied on a model system with two solutes to study the spectral behavior of cross peaks in 2D asynchronous spectra generated by using the DAOSD approach. Variations on different spectral parameters, such as peak position, bandwidth, and absorptivity, caused by intermolecular interactions can be estimated by the characteristic spectral patterns of cross peaks in the pair of complementary sub-2D asynchronous spectra. Intermolecular interactions between benzene and iodine in CCl<sub>4</sub> solutions were investigated using the DAOSD approach to prove the applicability of the DAOSD method in real chemical system

    Enteric Polymer Based on pH-Responsive Aliphatic Polycarbonate Functionalized with Vitamin E To Facilitate Oral Delivery of Tacrolimus

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    To improve the bioavailability of orally administered drugs, we synthesized a pH-sensitive polymer (poly­(ethylene glycol)–poly­(2-methyl-2-carboxyl-propylene carbonate)–vitamin E, mPEG–PCC–VE) attempting to integrate the advantages of enteric coating and P-glycoprotein (P-gp) inhibition. The aliphatic polycarbonate chain was functionalized with carboxyl groups and vitamin E via postpolymerization modification. Optimized by comparison and central composite design, mPEG<sub>113</sub>–PCC<sub>32</sub>–VE<sub>4</sub> exhibited low critical micelle concentration of 1.7 × 10<sup>–6</sup> mg/mL and high drug loading ability for tacrolimus (21.2% ± 2.7%, w/w). The pH-responsive profile was demonstrated by pH-dependent swelling and <i>in vitro</i> drug release. Less than 4.0% tacrolimus was released under simulated gastric fluid after 2.5 h, whereas an immediate release was observed under simulated intestinal fluid. The mPEG<sub>113</sub>–PCC<sub>32</sub>–VE<sub>4</sub> micelles significantly increased the absorption of P-gp substrate tacrolimus in the whole intestine. The oral bioavailability of tacrolimus micelles was 6-fold higher than that of tacrolimus solution in rats. This enteric polymer therefore has the potential to become a useful nanoscale carrier for oral delivery of drugs
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