Pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) and pH-triggered release of pyranine from the complex micelles

The pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG114-b-P4VP61) in aqueous solutions and pH-triggered release of pyranine from the complex micelles were studied by dynamic and static light scattering, transmission electron microscopy, 1H NMR spectroscopy, and UV-vis spectroscopy. At pH 2, the ionized pyranine can ionically cross-link the protonated P4VP block and result in well-defined spherical complex micelles with a P4VP/pyranine core surrounded by a PEG corona. The ratio of pyranine to pyridyl units can influence the structure and the properties of the resultant complex micelles. The complex micelles are stable upon dilution and heating but are sensitive to pH changes. pH-triggered release of the incorporated pyranine from the complex micelles demonstrates that the release behavior is pH-tunable and displays good controlled-release characteristics at pH approximately 4.     

Polyion micelles with diphase-segregated core: electrostatic self-assembly of poly(ethylene glycol)-<Emphasis Type="Italic">block</Emphasis>-poly(4-vinylpyridium) and tetrakis (4-sulfonatophenyl) porphyrin in solution

The polyion micelles were prepared with poly(ethylene glycol)-block-poly(4-vinylpyridium) (PEG₁₁₄-b-P(4-VPH+)₃₅) and tetrakis (4-sulfonatophenyl) porphyrin (TPPS) in acid aqueous solution. Micellization was investigated by using a combination of static and dynamic laser scattering. UV–Vis spectroscopy revealed that the H- and J-type aggregates of TPPS were formed in the micellar core. Transmission electron microscopy studies of the polyion micelles show that the obtained polyion micelles take a diphase-segregated core, the polymer phase and the incompatible TPPS aggregates phase.     

Influence of metalation on the morphologies of poly(ethylene oxide)-block-poly(4-vinylpyridine) block copolymer micelles

Micellization of a poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO45-b-P4VP28) copolymer in water during metalation (incorporation of gold compounds and gold nanoparticle formation) with three types of gold compounds, NaAuCl4, HAuCl4, and AuCl3, was studied using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The transformations of the PEO45-b-P4VP28 block copolymer micelles in water were found to depend on a number of parameters including the thermal history of the as-prepared block copolymer, the type of the metal compound, and the metal loading. For the HAuCl4-filled PE045-b-P4VP28 micelles, the subsequent reduction with hydrazine hydrate results in a significant fraction of rodlike micelles, suggesting that slow nucleation (confirmed by the formation of the large gold nanoparticles) and facilitated migration of gold ions yields the ideal conditions for sphere-to-rod micellar transition.     

含pH敏感聚(4-乙烯基吡啶)的嵌段共聚物成核胶束化过程的NMR研究

利用NMR技术研究了聚乙二醇-b-聚(4-乙烯基吡啶)(PEG114-b-P4VP107)和聚(N-异丙烯基丙烯酰胺)-b-聚(4-乙烯基吡啶)(PNIPAM53-b-P4VP260)在逐步降低聚(4-乙烯基吡啶)链段质子化程度时嵌段共聚物的胶束化过程.在开始形成胶束时,吡啶环上氢原子的自旋-晶格弛豫时间(T1)急剧减小.结果表明,PEG114-b-P4VP107在质子化程度降为0.54时已有胶束生成;PNIPAM53-b-P4VP260在质子化程度降为0.58时也能观测到胶束生成的信号.将两个嵌段共聚物各自制得胶束的溶液相混合,观测到了发生在高分子链间的2DNOE信号,这表明所制得溶液中胶束与高分子链间有链交换的动态平衡.     

带有可调通道的嵌段共聚物胶束对药物的控制释放

用聚丙烯酸叔丁酯-b-聚乙二醇(PtBA45-b-PEG114)和聚丙烯酸叔丁酯-b-聚4-乙烯基吡啶(PtBA60-b-P4VP80)制备了复合胶束. 该胶束在pH=2.5的酸性水溶液中形成以PtBA为核, PEG和P4VP为壳的稳定球型结构. 在pH=12时, 壳层的P4VP链段变为疏水, 塌缩在PtBA的核上形成内壳, PEG链段继续保持溶解状态, 与成核的PtBA连接并穿过塌陷的P4VP内壳, 形成胶束的冠, 由于PEG处于溶解状态, 其分子链间有比较大的空隙, 可以控制一些小分子通过, 在胶束的表面形成通道. 该通道类似于生物膜的蛋白通道, 可以控制PtBA核与外界进行能量或物质交换的速度. 以布洛芬为模型分子, 负载在胶束内进行药物控制释放研究的结果表明, 胶束表面的通道可以起到明显控制布洛芬释放速度的作用, 并且药物的释放速度与通道在胶束表面的比例成正比.     

Surface Complexation Modeling of K(+), NO(3)(-), SO(4)(2-), Ca(2+), F(-), Co(2+), and Cr(3+) Ion Adsorption on Silica Gel

Surface complex formation of K(+), NO(3)(-), SO(4)(2-), Ca(2+), F(-), Co(2+), and Cr(3+) ions was determined on the surface of silica gel. Experimental data obtained by acid-base titration of suspensions were interpreted in terms of the triple-layer model. The value of the deprotonation constant of surface OH could be determined precisely but the protonation constant was rather uncertain. The logarithms of ion pair formation constants for K(+), NO(3)(-), Ca(2+), and SO(4)(2-) adsorbed in the beta-plane are log K(ipM,X) approximately 0, therefore these species can be considered inert ions in the investigated pH range. F(-), Co(2+), and Cr(3+) ions were found to be strongly sorbed in the o-plane. In order to provide a good fit and to obtain parameters independent of their initial values, all possible equilibrium must be accounted for in the models. Copyright 2001 Academic Press.     

SOx on ceria from adsorbed SO2

Results from first-principles calculations present a rather clear picture of the interaction of SO(2) with unreduced and partially reduced (111) and (110) surfaces of ceria. The Ce(3+)∕Ce(4+) redox couple, together with many oxidation states of S, give rise to a multitude of SO(x) species, with oxidation states from +III to +VI. SO(2) adsorbs either as a molecule or attaches via its S-atom to one or two surface oxygens to form sulfite (SO(3)(2-)) and sulfate (SO(4)(2-)) species, forming new S-O bonds but never any S-Ce bonds. Molecular adsorption is found on the (111) surface. SO(3)(2-) structures are found on both the (111) and (110) surfaces of both stoichiometric and partially reduced ceria. SO(4)(2-) structures are observed on the (110) surface together with the formation of two reduced Ce(3+) surface cations. SO(2) can also partially heal the ceria oxygen vacancies by weakening a S-O bond, when significant electron transfer from the surface (Ce4f) into the lowest unoccupied molecular orbital of the SO(2) adsorbate takes place and oxidizes the surface Ce(3+) cations. Furthermore, we propose a mechanism that could lead to monodentate sulfate formation at the (111) surface.     

Study on PEG-（NH4）2SO4 Aqueous Two-Phase System and Distribution Behavior of Drugs

The distribution behavior of chlorpromazine hydrochloride (CPZ), procaine hydrochloride (PCN) and procaine amide hydrochloride (PCNA) in polyethylene glycol (PEG800 or PEG1500)-(NH4)2SO4 aqueous two-phase systems has been investigated. The result shows that the PEG-(NH4)2SO4 aqueous two-phase system has potential extraction capability in small molecular drug separation. In PEG800-(NH4)2SO4 system, the extraction efficiencies (E) of CPZ, PCN and PCNA amount to 92.8%, 74.5% and 74.4%, respectively, with the distribution coefficients (KD) being 25.7, 5.9 and 5.8, correspondingly. In PEG1500-(NH4)2SO4 system, the extraction efficiencies (E) of CPZ,PCN and PCNA are 93.7%, 71.3% and 63.2%, respectively, with distribution coefficients (KD) of 39.6, 6.6 and 5.0,correspondingly. Based on the study on ultraviolet and fluorescence spectra and also distribution behavior of the drugs in PEG-(NH4)2SO4 aqueous two-phase system, extraction mechanism was further proposed that both hydrogen bond and hydrophobic interaction are involved in extraction.     

Study of the ordered structures of poly(styrene-b-vinyl4pyridine) in a solution state by using small-angle X-ray scattering and generalized indirect Fourier transform

The structures of the mesophases and their subunits (micelles) of poly(styrene-b-vinyl4pyridine) (PS-b-P4VP) in a toluene solution were studied by using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and generalized indirect Fourier transform (GIFT) methods. The structures of PS-b-P4VP, such as the individual micelle, the face-centered cubic (fcc) and body-centered cubic (bcc), and the lamellar, were identified. The SAXS from the PS-b-P4VP solution showed a good contrast for the micelle, even in a low concentration of 0.25 wt %. As the concentration increases, the fcc and both fcc and bcc appear for the packing of the micelles of PS(3.3K)-b-P4VP(4.7K) and PS(12K)-b-P4VP(11.8K), respectively. The lamellar structure was also identified, with a further increase in the concentration for PS(3.3K)-b-P4VP(4.7K). These structures were also identified via TEM images.     

Synthesis and photoactivity of pH-responsive amphiphilic block polymer photosensitizer bonded zinc phthalocyanine

A zinc tetraaminophthalocyanine derivative, zinc tetra(methacryloyl moiety)aminophthalocyanine (MeZnAPc) (with a double bond) was synthesized by the reaction between zinc tetraaminophthalocyanine (ZnTAPc) and methacryloyl chloride. Atom transfer radical polymerization (ATRP) was employed as the polymerization technique to obtain a novel pH-responsive polymeric photosensitizer (PEG110-b-P(DPAn-co-MeZnAPcm)) by copolymerizing of methoxypolyethylene glycols (MPEG) (as reducing agent), 2-(isopropylamino)ethyl methacrylate (DPA) and MeZnAPc. This photosensitizer was characterized by UV-vis spectroscopy, FTIR, H NMR, etc. The results indicated that the photosensitizer presented the well pH-responsive be 1 havior around the pH range 6.0-6.5 and the high photoactivity to 1,3-diphenylisobenzofuran (DPBF). The result of photocatalysis oxidation of L-tryptophan (L-Try) suggested that zinc phthalocyanine could present high photoactivity due to its dispersivity at pH 5.5 without formation of micelles, and its photoactivity decreased dramatically at pH 7.4 due to wrapping ZnTAPc into the micelles. Therefore, the novel pH-responsive polymeric photosensitizer has better application prospects in the field of photodynamic therapy.     

Morphology and thermoresponsive behavior of hybrid micelles of polystyrene-b-poly((N-isopropyl acrylamide)-co-(4-vinylbenzyl chloride)) with Prussian blue

The hybrid micelles of polystyrene-b-poly((N-isopropyl acrylamide)-co-(4-vinylbenzyl chloride)) block copolymer(PS-b-P(NIPAM-co-VBC)) with Prussian blue(PB) in the corona were prepared by reaction of pentacyano(4-(dimethylamino)-pyridine)ferrate(Fe-DMAP)-attached PS-b-P(NIPAM-co-VBC) with Fe Cl3. The formation of the PB framework inside the micelles was verified by UV-Vis, FTIR and TGA. The morphology of the hybrid micelles was studied by TEM and compared with that of the neat and Fe-DMAP-attached PS-b-P(NIPAM-co-VBC). It is found that attachment of Fe-DMAP may change the short rod-like micelles of the neat PS-b-P(NIPAM-co-VBC) into spherical ones and lead to a smaller micelle size. The morphology of the hybrid micelles may be altered or remain unchanged after formation of the PB framework, depending on the chain structure of PS-b-P(NIPAM-co-VBC) and starting concentration. The thermoresponsive behavior of different micelles was studied using DLS. It is observed that attachment of Fe-DMAP can improve the hydrophilicity of the P(NIPAM-co-VBC) block, leading to weaker hysteresis of the micelle size during the heating and cooling cycle. However, the crosslinked PB framework in the micellar corona may result in a more evident hysteresis phenomenon and blur the two-stepwise change of the micellar size with temperature.     

铟在聚乙二醇-硫酸铵双水相体系中的分配

研究了稀散元素铟在有配合剂PAR（4－（2－吡啶偶氮）－间苯二酚）存在和无PAR存在的聚乙二醇PEG－（NH4）2SO4双水相体系中的分配行为。讨论了酸度、PEG分子量、PEG浓度及温度等因素对铟分配比的影响，发现酸度对分配比的影响最大，随着PEG分子量的增加及温度的上升分配比逐渐增大；随着PEG浓度的增加分配比逐渐减小。     

Systematic and in situ energy dispersive X-ray diffraction investigations on the formation of lanthanide phosphonatobutanesulfonates: Ln(O(3)P-C(4)H(8)-SO(3))(H(2)O) (Ln = La-Gd)

Using the flexible linker H(2)O(3)P-C(4)H(8)-SO(3)H (H(3)L) and rare earth ions Ln(3+) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) we were able to synthesize the new isostructural inorganic organic hybrid compounds Ln(O(3)P-C(4)H(8)-SO(3))(H(2)O). High-throughput experiments were employed to study the influence of the molar ratios Ln:H(3)L and pH on the product formation. The crystal structure of the compounds Sm(O(3)P-C(4)H(8)-SO(3))(H(2)O) (1) and Pr(O(3)P-C(4)H(8)-SO(3))(H(2)O) (2) were determined by single crystal diffraction. The structures are built up from chains of edge-sharing LnO(8)-polyhedra that are connected by the phosphonate and sulfonate groups into layers. These layers are linked by the -(CH(2))(4)- group to form a three-dimensional framework. The synthesis of compound 1 was scaled up in a conventional oven as well as in a microwave reactor system. A modification of a microwave reactor system allowed its integration into the beamline F3 at HASYLAB, DESY, Hamburg. The crystallization was investigated in situ by means of energy dispersive X-ray diffraction using conventional as well as microwave heating methods applying temperatures varying from 110 to 150 °C. The formation of Sm(O(3)P-C(4)H(8)-SO(3))(H(2)O) takes place in two steps. In the first step a crystalline intermediate was observed, which transforms completely into compound 1. The method by Sharp and Hancock was used to determine the rate constants, reaction exponents, and the Arrhenius activation energy for both reaction steps. Comparing both heating methods, microwave heating leads to fully crystallized reaction product after shorter reaction times, but neither the temperature nor the heating method has significant influence on the induction time.     

pH响应两亲嵌段锌酞菁聚合物光敏剂的制备及光活性

将氨基锌酞菁（ZnTAPc）与甲基丙烯酰氯反应制备出含有不饱和双键的取代锌酞菁衍生物（MeZnAPc）,采用ATRP法将聚乙二醇单甲醚大分子引发剂（mPEG110-Br）与甲基丙烯酸（2-异丙胺基）乙酯（DPA）和MeZnAPc共聚,制得一种新型pH响应两亲嵌段锌酞菁聚合物光敏剂（PEG110-b-P（DPAn-co-MeZnAPcm））.用1HNMR,FTIR对MeZnAPc和聚合物光敏剂进行表征.UV-vis测试表明该聚合物光敏剂在pH6.0～6.5具有较好的pH响应性.以1,3-二苯基苯并呋喃（DPBF）为底物研究了该聚合物光敏剂的光催化氧化效率,结果表明其具有较高光活性.利用该聚合物光敏剂在不同pH的水溶液中对L-色氨酸进行光催化氧化实验,结果发现在pH5.5不存在胶束时,锌酞菁可以较好地分散在溶液中,并能维持较高光活性,而在pH7.4形成胶束时可以将锌酞菁很好地包裹在其内部,使其光活性大大降低.因此,这种pH响应两亲嵌段锌酞菁聚合物作为一种新型光敏剂,在光动力学治疗领域有较好的应用前景.     

On the hydrolysis of the dioxouranium(VI) ion in sulfate solutions

The formation of ternary UO2(2+)-(OH-)-SO4(2-) complexes has been studied at 25 degrees C in 3 M NaClO4 ionic medium by measurements with a glass electrode. The solutions had uranium concentrations between 0.3 and 30 mM, sulfate between 20 and 200 mM, and 1.66 < or = [SO4(2-)]/[U(VI)] < or = 300. The hydrogen ion concentration ranged from 10(-3) M to incipient precipitation of basic sulfates. This occurred, depending on the metal concentration, at [H+] between 10(-4) and 10(-5.3) M. In the interpretation of the data the stabilities of binary complexes were assumed from independent sources. The data could be explained with the mixed complexes and equilibria (beta(pqr)(3sigma) refers to pUO2(2+) + qH2O + rSO4(2-) <==> (UO2)p(OH)q(SO4)r(2p-q-2r) + qH+): logbeta222 = -2.94 +/- 0.03, logbeta341 = -9.82 +/- 0.06, logbeta211 = -0.30 +/- 0.09, logbeta212 = 1.09 +/- 0.09, logbeta351 = -15.04 +/- 0.09 and logbeta462 = -14.40 +/- 0.06. The fit could be improved by including UO2OH+ with logbeta110 = -5.1 +/- 0.1. The identity of the minor species remains, however, an open question.     

Confinement effects on the interaction of native DNA with Cu(II)-5-(triethylammoniummethyl)salicylidene ortho-phenylendiiminate in C(12)E(4) liquid crystals

Confinement effects of native calf thymus DNA interacting with the complex Cu(ii)-5-(triethylammoniummethyl)salicylidene ortho-phenylendiiminate (CuL(2+)) perchlorate in tetraethylene glycol monododecyl ether (C(12)E(4)) liquid crystals have been investigated by UV absorption spectrophotometry, circular dichroism (CD) and small angle X-ray scattering (SAXS). The results indicate the occurrence of dramatic structural changes of both the DNA and the CuL(2+)-DNA system, when going from aqueous solution to C(12)E(4) liquid crystals, due to confinement constrains imposed by the closed structure of C(12)E(4) reverse micelles. Further marked departures from the behaviour observed in aqueous solution have been emphasized by registering the spectral response of DNA and CuL(2+)-DNA confined in C(12)E(4) reverse micelles after thermal treatment. It has been also ascertained that the confinement causes the formation of a more compact and thermoresistant DNA structure accompanied by a transition from the right- to left-handed form while a tight CuL(2+)-DNA binding has been revealed by the appearance of a broad induced CD band in the range 350-450 nm. From a biological point of view, these findings stress the need to account for confinement effects and the peculiarity of drug-DNA interactions occurring within the intra-cellular environment.     

HNO3-NHx, H2SO4-NHx, CH(O)OH-NHx, and CH3C(O)OH-NHx complexes and their role in the formation of condensation nuclei

The formation of sulfuric acid (H(2)SO(4)), nitric acid (HNO(3)), acetic acid (CH(3)C(O)OH), and formic acid (HC(O))H) complexes with ammonia (NH(3)), amidogen radical (NH(2)), and imidogen radical (NH) was studied using natural bond orbital calculations. The equilibrium structures, binding energies, and harmonic frequencies were calculated for each acid-NH(x) complex using hybrid density functional (B3LYP) and second-order M?ller-Plesset perturbation approximation methods with the 6-311++G(3df,3pd) basis set. The results presented here suggest that the effect of NH(2) on the formation of new condensation nuclei will be similar to that of NH(3), but to a lesser degree and confined primarily to complexes with H(2)SO(4) and HNO(3). The NH radical is not expected to play a significant role in the formation of new atmospheric condensation nuclei.     

Purely salt-responsive micelle formation and inversion based on a novel schizophrenic sulfobetaine block copolymer: structure and kinetics of micellization

A novel sulfobetaine block copolymer, poly(N-(morpholino)ethyl methacrylate)-b-poly(4-(2-sulfoethyl)-1-(4-vinylbenzyl)pyridinium betaine) (PMEMA-b-PSVBP), was synthesized via reversible addition-fragmentation chain transfer polymerization. In aqueous solution, PMEMA homopolymer becomes insoluble in the presence of Na2SO4 (>0.6 M), whereas PSVBP homopolymer molecularly dissolves in the presence of NaBr (>0.2 M). Thus, PMEMA-b-PSVBP diblock copolymer exhibits purely salt-responsive "schizophrenic" micellization behavior in aqueous solution, forming two types of micelles with invertible structures, that is, PMEMA-core and PSVBP-core micelles, depending on the concentrations and types of added salts (Scheme 1). The equilibrium structures of these two types of micelles were characterized via a combination of 1H NMR and laser light scattering (LLS). We further investigated the kinetics of salt-induced formation/dissociation of PMEMA-core and PSVBP-core micelles and the structural inversion between them employing the stopped-flow light scattering technique. In the presence of 0.5 M NaBr, the addition of Na2SO4 (>0.6 M) induces the formation of PMEMA-core micelles stabilized with well-solvated PSVBP coronas. Dilution-induced dissociation of PMEMA-core micelles into unimers occurs within the dead time of the stopped-flow apparatus (approximately 2-3 ms) when the final Na2SO4 concentration drops below 0.3 M, while salt-induced breakup of PSVBP-core micelles is considerably slower. The structural inversion from PMEMA-core to PSVBP-core micelles proceeds first with the dissociation of PMEMA-core micelles into unimers, followed by the formation of PSVBP-core micelles. On the other hand, structural inversion from PSVBP-core to PMEMA-core micelles exhibits different kinetic sequences. Immediately after the salt jump, PMEMA corona chains are rendered insoluble, and unstable PSVBP-core micelles undergo intermicellar fusion; this is accompanied and/or followed by the solvation of PSVBP cores and structural inversion into colloidally stable PMEMA-core micelles.