Water-soluble porphyrin-PAMAM-conjugates of melphalan and their anticancer activity

p-[bis(chloro-2-ethyl)amino]-L-phenylalanine (melphalan) is an approved anti-cancer agent with a broad spectrum of antitumor activity. However, it has some disadvantages, such as poor water-solubility followed by rapid elimination, which reduce the target specificity. To solve these problems, porphyrin- poly(amidoamine) or PAMAM-conjugates of melphalan were synthesized and characterized. The dendrimeric conjugates showed satisfactory water solubility. It was found that the size of the dendrimer played a crucial role in controlling the drug content and diameter of the melphalan-conjugates. The in vitro studies of cell cytotoxicity revealed that by employing the dendrimeric conjugation strategy and using the PAMAM dendritic arms as spacers, the conjugates had good anti-cancer activity and lower toxicity than free melphalan.     

Diphenolic acid-modified PAMAM/chlorinated butyl rubber nanocomposites with superior mechanical,damping, and self-healing properties

ABSTRACT

Based on its excellent damping properties, traditional rubber has been widely used in various industries, including aerospace, rail transit and automotive. However, the disadvantages of effective damping area, unstable damping performance, easy fatigue, and aging, greatly limited the further application of rubber materials. Thus, it is important to develop novel modified rubber damping materials. Herein, polyamidoamine dendrimers with terminal-modified phenolic hydroxyl and amine groups (G2 PAMAM-H) were designed and used as modifiers to improve the damping performance of chlorinated butyl rubber (CIIR). The results showed that the modification of G2 PAMAM by diphenolic acid can avoid its aggregation in the CIIR matrix. CIIR/G2 PAMAM-H nanocomposites exhibited high tan δ _max of 1.52 and wide damping temperature region of 140°C (tan δ > 0.55)at a very low loading (4.32 wt.%), which were strongerthan that of pure CIIR and CIIR/G2 PAMAM nanocomposites. In addition, these nanocomposites also exhibited a unique self-healing ability by multiple hydrogen bonds, which can effectively extend the life of the rubber material in actual production. Therefore, the dendrimer modification provided unique development opportunities for elastomers in certain highly engineered fields, such as vehicles, rail transit, aerospace, etc.     

聚酰胺胺(PAMAM)树形分子用作乳化炸药的稳定剂

用PAMAM树形分子作稳定剂制成了一种新型的乳化炸药,并用高低温循环及室温贮存的电导率测试、扫描电镜等技术对其稳定性作了表征.结果表明,用PAMAM稳定后的乳化炸药具有很好的稳定性,对该乳化炸药的爆速测试结果表明,添加PAMAM后的乳化炸药的爆速反而增加.同时,对此乳化炸药的稳定机理作了初步探讨.     

微波合成树枝状高分子聚酰胺-胺及其荧光性质

采用微波法合成了PAMAM,反应时间由常温下的24 h缩短到数十分钟,并研究了产物的荧光性质,微波下合成产物随代数增加有一定的线性变化规律,并初步研究了PAMAM与药物的相互作用。     

Spectroelectrochemical analysis of ion-transfer and adsorption of the PAMAM dendrimer at a polarized liquid|liquid interface

The interfacial behavior of the fourth generation polyamidoamine (G4 PAMAM) dendrimer at a water|1,2-dichloroethane (DCE) interface was studied by cyclic voltammetry and potential modulated fluorescence (PMF) spectroscopy. Irregular voltammetric responses were observed at positively polarized interfaces. The cyclic voltammogram was strongly dependent on pH and on the concentrations of the G4 PAMAM dendrimer and the organic supporting electrolyte. PMF spectroscopy was successfully used to analyze the interfacial mechanism of the dendrimer by adding an anionic porphyrin derivative as a fluorescent probe. The results of the PMF measurements demonstrated that the G4 PAMAM dendrimer was transferred across the interface, a process that was accompanied by an adsorption step at pH 7. In contrast, under alkaline conditions, the adsorption process did not seem to be involved in the interfacial behavior.     

Poly(amidoamine), polypropylenimine, and related dendrimers and dendrons possessing different 1 → 2 branching motifs: An overview of the divergent procedures

This review presents an overview of 1 → 2 branched dendrimers and dendrons, created by a divergent procedure, from their synthesis to modern day applications. The first members of this branched class of fractal macromolecules were prepared through a cascade synthesis, which was later replaced by the iterative divergent synthetic approach. Most classes of this 1 → 2 N-, Aryl-, C-, Si-, and P-branched families are included and catalogued by their mode of connectivity. Dendritic macromolecules have had significant impact in the field of material sciences and are one of the major starting points for nanotechnology as a result of the numerous modifications that can be conducted, either on the surface or within their molecular infrastructure, thus taking advantage of their unimolecular micelle properties. These host cavities, maintained by the dendritic branches, allow for the incorporation of nanoparticles as well as metal particles, which make these attractive in catalysis and imaging studies. The solubility of these fractal constructs can be tailored depending on their surface modifications. Highly water-soluble, neutral dendrimers appended with, grown from, or acting as hosts to specific molecules give rise to a wide variety of biomedical applications such as drug delivery systems and MRI imaging agents. The inherent supramolecular or supramacromolecular chemistry has been exploited but the design and construction of uniquely tailored macrostructures have just begun. Laser dyes, as well as electron and energy donor and acceptor functionality, have also been paired with these fractal constructs in order to probe their uses in the field of molecular electronics. With their synthetic control, seemingly limitless modifications and wide variety of potential applications, as well as their now commercial availability, these 1 → 2 branched dendrimers have become an important nanostructured tools for diverse utilitarian applications. This review mainly covers 1 → 2 branched non-chiral dendrimers prepared by a divergent process but selected chiral surfaces are considered as well as metal encapsulation and a few hyperbranched routes to related imperfect dendrimers.