Babu Ponnusamy, Sinha Sharmistha, Surolia Avadhesha
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
Bioconjug Chem. 2007 Jan-Feb;18(1):146-51. doi: 10.1021/bc060204q.
One-pot synthesized neoglycoconjugates with a reactive thiol group are introduced here for functionalization with carbohydrates for solubilization and stabilization of CdSe-ZnS quantum dots in aqueous solution. Three different sizes of quantum dots (QDs) with lactose, melibiose, and maltotriose on their surface have been utilized, for the first time, for lectin detection through agglutination assay. The sugar-QDs thus synthesized were characterized by transmission election microscopy (TEM), fluorescence, and absorption spectroscopy. Agglutination of sugar-QDs by three different lectins occurred through specific multivalent carbohydrate-lectin interactions and was studied extensively by monitoring the scattered light at 600 nm. This assay was very selective, which has been demonstrated by a more selective binding of soybean agglutinin (SBA) with melibiose-QD, as compared to lactose-QD, and specific deagglutination caused by alpha-d-galactose, while alpha-d-mannose did not show any effect. The detection sensitivity of the maltotriose-QD was tested with Concanavalin A (ConA), and as little as 100 nM of the lectin was detected using light scattering. The detection sensitivity of this protocol has been enhanced considerably by the fluorescence properties of QDs. This agglutination process seems to occur through formation of smaller soluble aggregates, which further associate to form larger aggregates.
本文介绍了一种通过一锅法合成的带有反应性硫醇基团的新糖缀合物，用于与碳水化合物功能化，以实现水相中CdSe-ZnS量子点的增溶和稳定。首次利用表面带有乳糖、蜜二糖和麦芽三糖的三种不同尺寸的量子点（QDs），通过凝集试验检测凝集素。通过透射电子显微镜（TEM）、荧光和吸收光谱对如此合成的糖基量子点进行了表征。三种不同的凝集素对糖基量子点的凝集是通过特定的多价碳水化合物-凝集素相互作用发生的，并通过监测600 nm处的散射光进行了广泛研究。该试验具有很高的选择性，与乳糖量子点相比，大豆凝集素（SBA）与蜜二糖量子点的结合更具选择性，以及α-d-半乳糖引起的特异性解凝集都证明了这一点，而α-d-甘露糖则没有任何影响。用伴刀豆球蛋白A（ConA）测试了麦芽三糖量子点的检测灵敏度，利用光散射检测到低至100 nM的凝集素。量子点的荧光特性大大提高了该检测方法的检测灵敏度。这种凝集过程似乎是通过形成较小的可溶性聚集体发生的，这些聚集体进一步结合形成较大的聚集体。
