Preparation and evaluation of 2-methoxyestradiol-loaded pH-sensitive liposomes

The development and clinical application of 2-methoxyestradiol (2-ME) as a new type of antitumor drug are limited due to its poor solubility, rapid metabolism in vivo, and large oral dosage. 2-ME-loaded pHsensitive liposomes (2-ME-PSLs) was prepared containing the lipids, Lipoid E-80 (E-80), cholesteryl hemisuccinate (CHEMS), and cholesterol (CHOL) via thin-film ultrasonic dispersion. First, preparation conditions of 2-ME-PSLs were optimized by orthogonal test. Then 2-ME-PSL was characterized, and the release behavior and stability of 2-ME-PSL in vitro were evaluated. The optimal preparation conditions for 2-ME-PSLs were as follows: 2-ME : E-80+CHEMS 1:15; CHOL : E-80+CHEMS 1:5; ultrasonication time 20 minutes. The mean particle size, PDI, zeta potential, and entrapment efficiency (EE) of 2-MEPSLs were 116 ± 9 nm, 0.161 ± 0.025, −22.4 ± 1.7 mV, and 98.6 ± 0.5%, respectively. As viewed under a transmission electron microscope, 2-ME-PSLs were well dispersed and almost spherical. They exhibited significant pH-sensitive properties and were fairly stable when diluted with a physiological solution. In conclusion, 2-ME-PSLs were successfully prepared and possessed a favorable pH sensitivity and good dissolution stability with a normal solution

ARTICLES Fullerenes in Photoconductive Polymers. Charge Generation and Charge Transport

Fullerenes enhance the photoconductivity of photoconductive polymers. This paper studies the mechansim of enhancement both experimentally and theoretically. The effects of fullerene doping on the spectroscopic, charge generation, and charge transport properties of the polymer are reported. Electrical field effects and magnetic field effects are examined. On the basis of these data a charge generation mechansim involving a singlet of weak charge-transfer complex is proposed for fullerene-doped N-poly (vinylcarbazole). A new theoretical model combining both the Onsager and Marcus theory is developed to quantitatively account for the field-dependent charge generation efficiency in nonpolar medium. Fullerenes, C 60 and C 70 , 1 are known to be good electron acceptors. 2,3 They can form charge-transfer complexes 4,5 or charge-transfer salts 6 with electron donors such as aromatic amines. Ferromagnetism 6 and enhanced second-order optical nonlinearity 7 have been observed from these charge transfer complexes. The direct optical excitation of fullerene can lead to excited state electron transfer reactons, The first fullerene-based polymeric photoconductor was demonstrated by doping fullerenes into polymers containing electron-donating moieties such as N-poly(vinylcarbazole) (PVK). The purpose of this paper is to study the effects of fullerene doping on the charge transport and charge generation properties of the host photoconductive polymer. It will be shown that the effects of fullerene doping on the hole transport property of the polymer are minimal. So the main focus of the paper will be on the charge generation mechanism of fullerene-doped polymeric photoconductors, in particular, fullerene-doped PVK. It is known that, upon photoexcitation, the singlet state of C 60 and C 70 undergoes efficient intersystem crossing to generate a long-lived triplet state (lifetime varies from micro-to milliseconds depending on the conditions) with a quantum yield of almost 1. This paper also address a more general issue regarding the quantitative treatment of charge generation processes in polymers. The field-dependent charge separation theory of Onsager 29 has been the standard model to use for analyzing the charge generation efficiency of polymeric photoconductors for many years, in spite of its generally recognized deficiencies. The theory predicts the probability of an electron-hole (e-h) pair separating to infinity by solving the diffusion equation of the relative motion of the e-h pair in the potential provided by their Coulomb interaction and applied external field. The origin of the e-h pair and the pathway by which it is generated are not considered in the model. An important boundary condition (and an assumption) for this model is that if the e-h pair separation distance reaches zero, the pair annihilates (with an infinitively fast rate). For low dielectric constant solids, the theory predicts a strong field-dependent charge generation efficiency depending on the initial e-h separation distance. The shorter the initial separation distance, the stronger the field dependence. Over the past decades, the field-dependent charge generation efficiency of many polymeric photoconductors have been fitted to the Onsager theory with apparent success

Bis(4,4′-bipyrid­yl)bis{2-[4,6-bis­(carboxy­methyl­sulfan­yl)-1,3,5-triazin-2-ylsulfan­yl]acetato}zinc(II)

In the title compound, [Zn(C9H8N3O6S3)2(C10H8N2)2], the central ZnII ion, situated on a center of inversion, adopts an octa­hedral geometry coordinated by four O atoms from two carboxyl­ate groups and two carboxylic groups of two symmetry-related TTTA ligands and two N atoms from two bpy mol­ecules {TTTA is 2,2′,2′′-[1,3,5-triazine-2,4,6-triyltris(sulfanedi­yl)]triacetic acid and bpy is 4,4′-bipyridine}. These mononuclear units are connected through complementary O—H⋯X hydrogen bonds, as well as through weak C—H⋯X (X = O and N) inter­actions, resulting in a three-dimensional supra­molecular architecture

Poly[[μ2-1,3-bis­(imidazol-1-ylmeth­yl)benzene][μ2-2,2′-dihy­droxy-1,1′-methyl­enebis(naphthalene-3-carboxyl­ato)]zinc]

In the title compound, [Zn(C23H14O6)(C14H14N4)]n, the ZnII ion is four-coordinated in a distorted tetra­hedral geometry. The 1,3-bis­(imidazol-1-ylmeth­yl)benzene and 2,2′-dihy­droxy-1,1′-methyl­enebis(naphthalene-3-carboxy­l­ate) ligands con­nect the ZnII ions alternately in different directions, forming a layered structure parallel to the ac plane. Topological analysis reveals that the whole structure is a (4,4) network. The layers are further assembled into a three-dimensional supra­molecular structure via C—H⋯O and C—H⋯π inter­actions

Follow-up study of neuropsychological scores of infant patients with cobalamin C defects and influencing factors of cerebral magnetic resonance imaging characteristics

PurposeThe purpose of this study was to investigate whether baseline cerebral magnetic resonance imaging (MRI) characteristics could predict therapeutic responsiveness in patients with cobalamin C (cblC) defects.Materials and methodsThe cerebral MRI results of 40 patients with cblC defects were evaluated by a neuroradiologist. Neuropsychological scores and imaging data were collected. Neuropsychological tests were performed before and after standardized treatment.ResultsThirty-eight patients initially underwent neuropsychological testing [developmental quotient (DQ)]. CblC defects with cerebellar atrophy, corpus callosum thinning and ventricular dilation had significantly lower DQs than those without (P < 0.05). Through a multivariate linear stepwise regression equation after univariate analysis, ventricular dilation was the most valuable predictor of lower DQs. Thirty-six patients (94.7%) underwent follow-up neuropsychological testing. The pre- and post-treatment DQ values were not significantly different (Z = −1.611, P = 0.107). The post-treatment DQ classification (normal, moderately low, or extremely low) showed nearly no change compared to the pretreatment DQ classification (k = 0.790, P < 0.001).ConclusionVentricular dilation, cerebral atrophy and corpus callosum thinning are the main MRI abnormalities of cblC defects, and these manifestations are significantly correlated with delayed development in children. MRI findings can be considered an important tool for determining the severity of cblC defects