A dual microsphere based on PLGA and chitosan for delivering the oligopeptide derived from BMP-2

In this paper, we document the process and findings of preparing dual poly (lactide-co-glycolide)/chitosan microspheres (PLGA/CS MSs) for osteoinductive oligopeptide derived from BMP-2 (abbreviated as Peptide-24). Through adjusting the amount of Peptide-24, three kinds of PLGA/CS MSs were successfully constructed in twice encapsulations. We studied the morphology, size distribution and loading efficiency of the PLGA/CS MSs. We also focused on the pH change of the environment and the molecular weight of the matrix during the degradation process of PLGA/CS MSs. More specifically, the release of Peptide-24 from three kinds of PLGA/CS MSs was monitored in PBS at 37 °C and pH 7.4. The structural stability of the released Peptide-24 was detected by Far-UV circular dichroism and MALDI-TOF-MS analysis. The mean sizes of the three kinds of PLGA/CS MSs are 47.5, 63.0 and 89.1 μm; and their drug-loading rates are 2.61, 3.21 and 2.21%, respectively. Comparing with Chitosan microspheres (abbreviated as CS MSs), the PLGA/CS MSs have excellent release curves with zero-order kinetics and controllable model. The incubation solution of PLGA/CS MSs avoided producing acid environment as poly (lactide-co-glycolide) microspheres (PLGA MSs) did, which was explained by analyzing the molecular weight of the matrix. The released oligopeptide kept its original structure and relative molecular weight throughout the procedures of encapsulation, storage and release. This indicates its structure stability. Thus, we conclude that dual PLGA/CS MSs is a promising vehicle that is suitable for the delivery of bioactive factors.     

Selected reaction monitoring (SRM) mass spectrometry without isotope labeling can be used for rapid protein quantification

The validation of putative biomarker candidates has become the major bottle-neck in protein biomarker development. Conventional immunoaffinity methods are limited by the availability of antibodies and kits. Here we demonstrate the feasibility of using selected reaction monitoring (SRM) without isotope labeling to achieve fast and reproducible quantification of serum proteins. The SRM/MRM assays for three standard serum proteins, including ceruloplasmin (CP), serum aymloid A (SAA) and sex hormone binding globulin (SHBG), have good linear ranges, generally 10(3) to 10(4) . There are almost perfect correlations between SRM intensities and the loaded peptide amounts (R(2) is usually ~0.99). Our data suggest that SRM/MRM is able to quantify proteins within the range of 0.2-2 fmol, which is comparable to the commercial ELISA/LUMINEX kits for these proteins. Excellent correlations between SRM/MRM and ELISA/LUMINEX assays were observed for SAA and SHBG (R(2)=0.928 and 0.851, respectively). However, the correlation between SRM/MRM and ELISA for CP is less desirable (R(2)=0.565). The reproducibility for SRM/MRM assays is generally very good but may depend on the proteins/peptides being analyzed (R(2)=0.931 and 0.882 for SAA and SHBG, and 0.723 for CP). The SRM/MRM assay without isotope labeling is a rapid and useful method for protein biomarker validation in a modest number of samples and is especially useful when other assays such as ELISA or LUMINEX are not available.     

Total syntheses of Tardioxopiperazine A, Isoechinulin A, and Variecolorin C

First total syntheses of the isoechinulin-type alkaloids: Tardioxopiperazine A, Isoechinulin A, and Variecolorin C have been achieved from a common key intermediate 5, which was derived from a regiocontrolled Stille cross-coupling reaction of an allylindium reagent.     

Conformational changes of hapten-protein conjugates resulting in improved broad-specificity and sensitivity of an ELISA for organophosphorus pesticides

The type of hapten linkage to a carrier protein can play an important role in determining the nature of the resulting antibody response. Generic haptens using three types of linkers were synthesized (a monocarboxylic acid, an unsaturated hydrocarbon and a carboxamido spacer). These haptens were conjugated to bovine serum albumin (BSA) and used as immunogens to produce broad-specificity monoclonal antibodies (MAbs) to organophosphorus pesticides (OPs). Three-dimensional (3D) structures of hapten-lysine conjugates were optimized using molecular modeling (MM) to mimic conformations of hapten-BSA conjugates. The results from MM studies revealed a change of the 3D conformation and electrostatic potential of hapten 1 when the monocarboxylic acid linker was coupled to lysine. This result was consistent with the observed high-cross-reactivity of the corresponding MAb-H1 for the OPs. The competitive indirect enzyme-linked immunosorbent assay based on MAb-H1 is ideally suited to be used as a screening method for OP contaminants.     

Optical Resolution and Structure Determination of New Indolizidine Alkaloids from Elaeocarpus sphaericus

Two new indolizidine alkaloids, (±)‐3‐oxoisoelaeocarpine ( 1 ) and (±)‐elaeocarpine N‐oxide ( 2 ), along with three known alkaloids, (±)‐isoelaeocarpine ( 3 ), (±)‐elaeocarpine ( 4 ), and (?)‐isoelaeocarpiline ( 5 ), were isolated from an EtOH extract of the branches and leaves of Elaeocarpus sphaericus. The structures of these compounds were determined by spectroscopic and chemical methods. Furthermore, enantiomers of compounds 1 and 3 were separated on a chiral CD‐Ph column, and their absolute configurations were determined by TD‐DFT (=time‐dependent density‐functional theory) quantum‐chemical calculations of their electronic circular dichroism (ECD) spectra.     

Study on the interaction between clarithromycin and bovine serum albumin in the imitated physiology solution

The interaction between clarithromycin (CAM) and bovine serum albumin (BSA) was investigated using linear-sweep voltammetry in pH 7.4 phosphate buffer solution where CAM caused two irreversible reduction waves P2 and P3 on mercury electrode. The study showed that the formation constant and formation ratio for the interaction between CAM and BSA were 1.51×1012 and 3:1 for P2,4.53×105 and 1:1 for P3, respectively. The ion strength enhanced the hydrophobic interaction between CAM and BSA.     

基于嵌入式PC/104的狭缝摄影控制系统

介绍狭缝摄影和以PC／104作平台的狭缝摄影控制系统的工作原理，给出了控制系统硬件组成及软件设计方法。     

Improvement of all-optical switching effect based on azobenzene-containing polymer films

A method for improving the quality of all-optical switching is presented. Pumping poly(methyl methacrylate) (PMMA) films doped with azobenzene chromophore Disperse Red 1 (DR1) with two beams (a linearly and a circularly polarized), all-optical switching effects with very low background and high stability are demonstrated. High frequency switching, which is hard to be realized under pump of a single beam, is obtained. The circularly polarized pump beam can erase the photoinduced birefringence and quicken the relaxation process, thus lowering the background and improving the stability and the extinction ratio of the switching signal. PACS 42.70.Jk; 42.25.Lc; 82.30.Qt; 78.20.Fm; 77.80.Fm     

克尔型非线性薄膜波导的TE模

对于芯区为克尔型非线性介质，覆盖层和衬底为线性介质的平板波导，用Ｋｒｙｌｏｖ－Ｂｏｇｏｌｉｕｂｏｖ－Ｍｉｔｒｏｐｏｌｓｋｙ的渐近法导出了色散方程及场分布的二阶近似数学表达式，计算量大为减少且结果精确。给出了对称和非对称情况的典型实例。