A Concise Route to 3-Hydroxy-4-Methoxy-5-Methylbenzaldehyde Derivative

3-Hydroxy-4-methoxy-5-methylbenzaldehyde derivative (1c) has been synthesized in 7 steps from 2,3-dihydroxytoluene (4). An isopropyl derivative has been used to protect a phenol during this transformation. The overall yield of 1c was 37%.     

Native conjugation between proteins and [60]fullerene derivatives using SpyTag as a reactive handle

Herein,we report the facile conjugation between proteins and water-soluble [60]fullerene derivatives(DC₆₀) under native conditions using SpyTag as a reactive handle.Water-soluble [60] fullerene derivatives were first prepared via sequential Bingel-Hirsch reaction and "clicked" with SpyTag to give DC₆₀-SpyTag for native conjugation with proteins by the highly efficient SpyTag-SpyCatcher chemistry.The bioconjugation was confirmed by MALDI-TOF MS spectra and SDS-PAGE analysis.The TEM and UVvis spectroscopic study further revealed that the DC₆₀ could alter the optical performance and induce aggregation of the target proteins.It thus provides a general and robust method for modifying proteins with C₆₀ derivatives and could potentially be adapted for native conjugation between proteins and other nonbiological motifs as well.     

Synthesis of bi-metallic Au–Ag nanoparticles loaded on functionalized MCM-41 for immobilization of alkaline protease and study of its biocatalytic activity

In this work, Au–Ag nanoparticles (Au–Ag-bi-MNPs) have been prepared on amine functionalized Si-MCM-41 (NH₂–Si-MCM-41) particles through a reduction of AgNO₃ and HAuCl₄ by NaBH₄ at ambient conditions. Au–Ag-bi-MNPs loaded on the NH2–Si-MCM-41, provide a good biocompatible surface for immobilization of the enzyme alkaline protease. This immobilization, presumably due to bonding between core shell nanoparticles and OH in serine 183 in alkaline protease seems to be of an ionic exchange nature. We found that the alkaline protease immobilized on the Au–Ag-bi-MNPs/Si-MCM-41 is an active biocatalyst, stable at different pH and temperature. The bio catalytic activity of free alkaline protease in solution was 64 U/mg (Units per milligram), whereas that of the alkaline protease immobilized on Au–Ag-bi-MNPs/Si-MCM-41 was 75 U/mg. This improvement of the biocatalytic activity may be due to a really increased activity per molecule of immobilized enzyme or to a purification of the enzyme. The alkaline protease molecules immobilized on the (Au–Ag)/ NH₂-MCM-41 surface retained as much as 80% of the catalytic activity recorded at pH=8, and showed significant catalytic activity of alkaline protease in the bioconjugate material. The biocatalytic materials were easily separated from the reaction medium by mild centrifugation and exhibits excellent reuse and stability characteristics over four successive cycles. The optimum temperature ranged from 35 ^°C–55 ^°C and pH=8 for bioactivity of the alkaline protease in the assembly system was observed to be higher than that of the free enzyme in solution. The enzyme biocatalytic activity was monitored by UV-visible spectroscopy. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and dispersive analysis of X-RAY (EDAX) were used to characterize the size and morphology of the prepared materials.     

万古霉素修饰磁性纳米粒子的制备及其细菌分离功能

制备了万古霉素修饰的磁性纳米粒子, 并研究了其对金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coli BL21)的选择性吸附分离特性.     

Characterization of the coupling of quantum dots and immunoglobulin antibodies

Water-soluble quantum dots (QDs) were used to label goat anti-human immunoglobulin antibodies (Abs), and the labeling process was characterized by column purification. The QDs obtained in organic solvent were modified with mercaptoacetic acid (MAA) and became water-soluble. These water-soluble QDs were linked to the antibodies using the coupling reagents ethyl-3-(dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The linking process was shown to be effective by ultra-filter centrifugation and column purification. After comparing the quantities of Abs and water-soluble QDs involved in the linking reaction via column purification, it was found that a molar Abs:QD ratio of >1.2 resulted in most of the water-soluble QDs becoming covalently linked to the Abs. The circular dichroism (CD) spectra of Abs and QD–Ab conjugates were very similar to each other, indicating that the secondary structure of Abs remained largely intact after the conjugation. Finally, antigen (Ag)–antibody (Ab) recognition reactions perfomed on the surface of a glass slide showed that the conjugate retained the activity of Abs. This work lends support to the idea of linking biomolecules to QDs, and thus should aid the application of QDs to the life sciences. Figure Firstly in this work, the conjugates of QDs-Ab were separated from EDC&NHS in the column of Sephadex G-100(left up). Then the bioactivity of QDs-Ab was analyzed in the immunoassay (right) and the immunofluorescent signals were detected (left bottom) finally     

ω-Iodoalkyl(methyl)malonate Esters

Abstract

ω-Iodoalkyl(methyl)malonate esters have potential utility in the bioconjugate chemistry of steroids. A representative set of these esters with a variety of protecting groups and alkyl groups has been prepared. The compounds offer a range of elution values on silica, as well as several convenient deprotection options.

ω-Bromoalkyl(methyl)malonate esters are precursors of chalcogenobarbiturates, which, in radiolabeled form, may be useful as brain imaging agents.[1] Grigsby, R.A., Irgolic, K.J. and Knapp, F.F. 1983. Synthesis and spectral properties of diethyl organylchalcogenoalkyl(alkyl)malonates and 5-alkyl-5-(organylchalcogenoalkyl)barbiturates. J. Organomet. Chem., 259: 171–181.  [Google Scholar] Recently, we have become interested in the analogous ω-iodoalkyl(methyl)malonate esters because of their possible utility in the bioconjugate chemistry of steroids. It is known that steroids can be conjugated to platinum through a malonate moiety.[2] Gandolfi, O., Apfelbaum, H.C., Migron, Y. and Blum, J. 1989. Syntheses of cis-dichlorodiammineplatinum analogs having steroidal hormones bound to the metal atom via malonato bridges. Inorg. Chim. Acta, 161: 113–123.  [Google Scholar] Such platinated steroids are significant because of their potential as tissue-selective antitumor agents.     

含醛基可降解嵌段共聚物的合成及其生物缀合

以PEO-DDMAT为大分子RAFT试剂、BPO为引发剂,调控含醛基单体4-乙烯基苯甲醛(VBA)与不饱和环缩醛单体5,6-苯基-2-亚甲基-1,3-二氧七环(BMDO)的RAFT共聚合,获得一种新型含醛基、可降解的两亲性嵌段共聚物PEO-b-poly (VBA-co-BMDO),并对不同单体投料比下的共聚行为进行了研究.由于聚合物主链含有酯基,可以在水中碱性条件下进行降解.细胞毒性分析表明其具有良好生物相容性.该嵌段聚合物还可以通过醛基-氨氧基“点击”反应和模型生物分子氨氧基胆固醇(H2NO-Chol)形成稳定的聚合物-生物分子缀合物,该缀合物能在水溶液中自组装成纳米胶束.结果表明PEO-b-poly (VBA-co-BMDO)可以作为聚合物载体缀合含氨氧基的药物分子,在生物医药方面有良好的应用前景.     

EMPO-酪氨酸共价链接物的合成与ESR研究

本文设计并试验了一种环状硝酮(5-乙酰基-5-甲基吡咯啉环氮氧化合物, EMPO)与酪氨酸氨基的共价链接方法, 并用ESR实验检验了链接后所得探针对自由基的捕获性能. 新探针的特色体现在以下两方面: (1) 对氨基酸氨基的链接方法几乎适用于所有多肽(或蛋白质); (2) 环状硝酮捕获自由基的效率更高.     

Fabrication and kinetic studies of a novel silver nanoparticles-glucose oxidase bioconjugate

In this study, a new effective, pH and thermally stable glucose oxidase (GOX)-silver nanoparticles (AgNPs) bioconjugate was designed. AgNPs were synthesized based on the reduction of silver nitrate (AgNO₃) by sodium borohydride (NaBH₄) using two simple procedures. Periodic acid was used for oxidation of the GOX and emission of Lucifer yellow (LyCH) was monitored by spectrofluorometer for evaluation of the oxidation properties of the GOX. The oxidized GOX (Ox-GOX) was immobilized on AgNPs by its sugar moieties via 6-aminohexanoic acid (6AHA) as linker. A sample of the synthesized bioconjugate was loaded on 7.5% non-denaturing polyacrylamide gel electrophoresis (PAGE) to confirm its structural and physical stability. The results from enzymatic activity assay showed that the bioconjugate, GOX and Ox-GOX were similar in stability and activity in acidic and basic pH (optimum pH = 7.0-8.0). Based on the results from thermal stability assay, it was found that the activity of the bioconjugate was found to be higher at lower temperatures. The V_max of the bioconjugate, GOX, and Ox-GOX was estimated as 28.6, 6.2, and 6 IU μg⁻¹ enzyme and the K_m was calculated as 2.7, 9, and 9.5 mM, respectively. It was found that the immobilization method improves the activity and stability of the GOX in different pH and temperatures. As a conclusion, the proposed method opens up the way to the development of a new bioconjugate with potential use in sensing, and many find potential applications in clinical diagnostics, medicine, and industries.     

Efficient One-Pot Synthesis of Doxorubicin Conjugates Through Its Amino Group to Melanotransferrin P97

Abstract

The amino group of doxorubicin 1 is reacted with bis-NHS-ester linkers 6, or anhydrides 13 to offer in high yield modified doxorubicins 7–12 and 14–16, respectively. Compounds 7–12 are mono-NHS-esters, and can be directly coupled with melanotransferrin (p97), a useful vector with the ability to cross the blood-brain barrier, to yield the expected doxorubicin-p97 conjugates. Upon activating the carboxylic group with BTTU, compound 14–16 could be used in the same reaction. Structurally, the amino group of doxorubicin is covalently bonded to the amino groups of p97. The conjugates are potential candidates for treatment of brain tumors.