Effect of the incorporation of amino groups in a glucose-responsive polymer complex having phenylboronic acid moieties

A novel polymer complex system sensitive to glucose was studied as a candidate material for formulating a chemically regulated insulin release system. A ternary copolymer of N-vinyl-2-pyrrolidone (NVP), 3-acrylamidophenylboronic acid (AAm-PBA) and N,N-dimethylaminopropylacrylamide (DMAPAA) (poly(NVP-co-PBA-co-DMAPAA)) was synthesized by radical copolymerization. The phenylboronic acid group in this copolymer serves as a glucose sensor moiety. Poly(NVP-co-PBA-co-DMAPAA) was soluble in water in the pH range of 3–12, in sharp contrast to a binary copolymer of NVP and AAm-PBA (poly(NVP-co-PBA)) which showed solubility only under alkaline aqueous conditions, where the boronic acid group is in a tetrahedral ionized form. The protonated amino group in poly(NVP-co-PBA-DMAPAA) contributed to increase the solubility of the polymer under physiological and acidic aqueous conditions. Furthermore, poly(NVP-co-PBA-co-DMAPAA) formed a stable polymer complex gel with poly(vinyl alcohol) (PVA) in pH 7.4 phosphate buffered solution due to the formation of a covalent linkage between the boronic acid groups in ternary copolymer and diol units in PVA. The release of myoglobin as model protein from the complex gel was increased immediately after the addition of glucose, due to the transition of gel into sol state, indicating the feasibility of this complex gel as a candidate material for a glucose-responsive delivery system for insulin.     

Thunberginols C, D, and E, new antiallergic and antimicrobial dihydroisocoumarins, and thunberginol G 3'-O-glucoside and (-)-hydrangenol 4'-O-glucoside, new dihydroisocoumarin glycosides, from Hydrangeae Dulcis Folium.

New antiallergic and antimicrobial dihydroisocoumarins, thunberginols C, D, and E, were isolated from Hydrangeae Dulcis Folium, the fermented and dried leaves of Hydrangea macrophylla SERINGE var. thunbergii MAKINO, together with new dihydroisocoumarin glycosides, thunberginol G 3'-O-glucoside and (-)-hydrangenol 4'-O-glucoside. Their chemical structures have been determined on the basis of chemical and physicochemical evidence. Thunberginols C, D, E, G, and (-)-hydrangenol 4'-O-glucoside showed antiallergic activity in the in vitro bioassay using the Schults-Dale reaction in sensitized guinea pig bronchial muscle, and they also exhibited antimicrobial activity against oral bacteria.     

Reactions of aliphatic fluoro-alcohols with CHClF2 at atmospheric pressure

The reactions of aliphatic fluoro-alcohols with chlorodifluoromethane (CHClF₂) at atmospheric pressure were examined. In the reaction of CF₃CF₂CH₂OH, the difluoromethylated ether was obtained in moderate yield by using ethers such as 1,4-dioxane, diglyme and THF, or their mixtures with water as a reaction solvent. While acetal and orthoformate were also produced, the selectivity of the difluoromethylated ether could be improved by adding water to the reaction. The effect of water could be explained by the reaction mechanism.     

Static and dynamic behavior of 2:1 inclusion complexes of cyclodextrins and charged porphyrins in aqueous organic media

Two heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMe-beta-CD) molecules strongly include the peripheral substituents at the 5- and 15-positions of the charged meso-tetrasubstituted porphyrins, PorSub(4) [TPPS(4) (Sub = p-C(6)H(4)-SO(3)(-)), TPPOC3PS (p-C(6)H(4)-O-(CH(2))(3)-p-C(6)H(4)-SO(3)(-)), TCPP (Sub = p-C(6)H(4)-CO(2)(-)), and TPPOC3Py (p-C(6)H(4)-O-(CH(2))(3)-Py(+)Br(-)), where Py(+) = N-alkylpyridinium] in aqueous ethylene glycol. The binding constants (K(1) and K(2)) and the rate constants (k(1) and k(2)) for formation of the 1:1 and 2:1 complexes of TMe-beta-CD and PorSub(4) were determined. Both the binding constants and the rate constants for anionic TPPS(4), TCPP, and TPPOC3PS were much larger than those for cationic TPPOC3Py. The smaller k(1) and k(2) values for TPPOC3Py indicate a higher barrier for penetration of a cationic guest into the TMe-beta-CD cavity. The methyl groups at the rims and the cavity wall of the host are positively polarized due to the inductive effect of the ethereal oxygens. The positively polarized rims and interior of the host cavity should prevent the penetration of the cationic substituent of TPPOC3Py into the TMe-beta-CD cavity. The 2:1 TMe-beta-CD-PorSub(4) complexes are extraordinary stable in aqueous solutions, even in the case of cationic TPPOC3Py. Formation of both 1:1 and 2:1 complexes is promoted by negative and large enthalpy changes, suggesting a strong van der Waals interaction as the main binding force.     

Calorimetric study of correlated disordering in [Hdamel]2[Cu(II)(tdpd)2] x 2 THF crystal

The heat capacity of [Hdamel]2[Cu(II)(tdpd)2] x 2 THF was measured from 6 to 250 K by adiabatic calorimetry. There are four heat anomalies around 150 K associated with disordering in the orientation of the uncoordinated THF molecules and in the conformation of the out-of-plane allyl groups of [Hdamel](+) units. The total entropy of transition was determined to be 19.8 J K(-1) mol(-1), less than the 4R ln 2 (R = gas constant) expected from the crystal structure at room temperature. The smallness of the total entropy change on phase transitions proves the presence of the strong motional correlation between the adjacent allyl groups. The calorimetric conclusion agreed with the crystal structure at 200 K re-examined in this study.     

Structural characterization and reactivity of UO2(salophen)L and [UO2(salophen)]2: dimerization of UO2(salophen) fragments in noncoordinating solvents (salophen = N,N'-disalicylidene-o-phenylenediaminate, L = N,N-dimethylformamide, dimethyl sulfoxide)

The molecular structures of UO2(salophen)L (L = DMF, DMSO) and a uranyl-salophen complex without any unidentate ligands (L) in solid and solution were investigated using single-crystal X-ray analysis and IR, 1H NMR, and UV-visible absorption spectroscopies. As a result, it was found that the uranyl-salophen complex without L is a racemic dimeric complex, [UO2(salophen)]2, in which the UO2(salophen) fragments are held together by bridging between one of the phenoxide oxygen atoms in salophen and the uranium in the other UO2(salophen) unit. Furthermore, it was spectrophotometrically demonstrated that [UO2(salophen)]2 retains its dimeric structure even in the noncoordinating solvents such as CH2Cl2 and CHCl3 and is in equilibrium with UO2(salophen)L {2UO2(salophen)L right arrow over left arrow [UO2(salophen)]2 + 2L}. The equilibrium constants and thermodynamic parameters of this equilibrium were evaluated from UV-visible absorption and 1H NMR spectral changes; log Kdim = -2.51 +/- 0.01 for L = DMF and solvent = CH2Cl2, log Kdim = -1.68 +/- 0.02 for L = DMF and solvent = CHCl3, log Kdim = -4.23 +/- 0.01 for L = DMSO and solvent = CH2Cl2, and log Kdim = -3.03 +/- 0.02 for L = DMSO and solvent = CHCl3. The kinetics of L-exchange reactions in UO2(salophen)L and enantiomer exchange of [UO2(salophen)]2 in noncoordinating solvents were also studied using NMR line-broadening method. As a consequence, it was suggested that the DMF-exchange reaction in UO2(salophen)DMF proceeds through two pathways (dissociative and associative paths) and that the predominant path of DMSO exchange in UO2(salophen)DMSO is the dissociative one. A sliding motion of the UO2(salophen) fragments was considered to be reasonable for the enantiomer-exchange mechanism of [UO2(salophen)]2. On the basis of the kinetic information for UO2(salophen)L and [UO2(salophen)]2, reaction mechanisms including the L-exchange reaction in UO2(salophen)L, the formation of [UO2(salophen)]2 from UO2(salophen)L, and the enantiomer exchange of [UO2(salophen)]2 are proposed.     

Preparation, characterization and properties of novel covalently surface-functionalized zinc oxide nanoparticles

Novel covalently surface-modified zinc oxide (ZnO) nanoparticles (NP) (ZHIE) were successfully prepared, which have organic chains composed of hydrophilic amide and urethane linkages, and terminal amino groups on the surfaces, using zinc acetate monohydrate. FTIR spectroscopy, X-ray analysis and TEM observation suggested that the resultant ZHIE NPs have the mean sizes of about 10 nm in diameters, the organic chains linking the amino groups in the terminals and wurtzite crystal structure. UV-vis absorption spectrum of the ZHIE NPs in methanol showed maximum absorption band at 348 nm, supporting the TEM observations. Photoluminescent spectrum measurements depicted that the ZHIE NPs show broad visible emission band on the basis of trapped-electron emission. Cytotoxicity and phagocytosis assays suggested that the ZHIE NPs are noncytotoxic, and the ZHIE-labeled zymosan particles derived by conjugation of the ZHIE NPs with zymosan are internalized into the cells and generate fluorescence based on the ZHIE NPs.