Department of Chemistry, Dyal Singh College, University of Delhi, Lodhi Road, Delhi 110003, India.
Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110007, India.
J Colloid Interface Sci. 2014 Feb 15;416:151-60. doi: 10.1016/j.jcis.2013.10.057. Epub 2013 Nov 8.
Click chemistry has found wide application in drug discovery, bioconjugation reactions, polymer chemistry and synthesis of amphiphilic materials with pharmaceutical and biomedical applications. Triazole substitution via a click reaction alters photophysical properties of coumarin. Both coumarin and triazole moieties participate in π-π stacking interactions. Hence it should be possible to prepare fluorescent self-assembly systems by conjugation of coumarin to poly (ethylene glycol) (PEG) via click reactions exhibiting hydrophilic, hydrophobic and π-π stacking interactions. Moreover, the materials can be suitable platforms to assess fluorescence modulation effect of triazole substitution on coumarins.
PEG supported coumarin conjugates were synthesized and the fluorescence modulation effect of the formation of triazole on coumarin was assessed. Their aggregation properties were studied by surface tension measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM), fluorescence and (1)H NMR spectroscopy.
The conjugates were found to form nanoaggregates in the size range of 100-120 nm with a negative free energy of micellization (~-27 kJ mol(-1)) confirming aggregation and self-assembly. The Quantum yield of 4-methyl-7-propargylcoumarin (7P4MC) was enhanced after triazole formation with azide functionalized PEG (methoxy-PEG350 azide). The conjugates were found to exhibit π-π stacking interactions in addition to hydrophilic and hydrophobic interactions. They were found to be biocompatible with human pancreatic cancer cells.
点击化学已在药物发现、生物偶联反应、聚合物化学和具有药物和生物医学应用的两亲材料的合成中得到广泛应用。通过点击反应进行三唑取代会改变香豆素的光物理性质。香豆素和三唑部分都参与π-π 堆积相互作用。因此，通过点击反应将香豆素共轭到聚乙二醇（PEG）上，制备具有亲水性、疏水性和π-π 堆积相互作用的荧光自组装体系是可行的。此外，这些材料可以作为评估三唑取代对香豆素荧光调制效果的合适平台。
合成了 PEG 负载的香豆素缀合物，并评估了三唑形成对香豆素的荧光调制效应。通过表面张力测量、动态光散射（DLS）、透射电子显微镜（TEM）、荧光和（1）H NMR 光谱研究了它们的聚集性质。
发现这些缀合物在 100-120nm 的范围内形成纳米聚集体，胶束化的自由能为负值（~-27kJmol(-1)），证实了聚集和自组装。在与叠氮功能化 PEG（甲氧基-PEG350 叠氮化物）形成三唑后，4-甲基-7-炔丙基香豆素（7P4MC）的量子产率得到提高。这些缀合物除了具有亲水性和疏水性相互作用外，还表现出π-π 堆积相互作用。它们被发现与人胰腺癌细胞具有生物相容性。
