Characterization of multivalent lactose quantum dots and its application in carbohydrate-protein interactions study and cell imaging.
Characterization of multivalent lactose quantum dots and its application in carbohydrate-protein interactions study and cell imaging.
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DOI：
10.1016/j.bmc.2010.05.046
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发表时间：
2010-07
影响因子：
3.5
通讯作者：
Yang Yang-Yang;Min Yu;Tingting Yan;Zhihui Zhao;Yinlin Sha;Zhong-Jun Li
中科院分区：
文献类型：
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作者：
Yang Yang-Yang;Min Yu;Tingting Yan;Zhihui Zhao;Yinlin Sha;Zhong-Jun Li
我们以前报道了一种简便易行的方法制备一种新型的乳糖-CdSeS/ZnS量子点缀合物（Lac-QDs），表现出生物相容性，无细胞毒性和对白细胞的特异性。为了进一步研究碳水化合物-蛋白质相互作用，制备了一系列具有不同乳糖密度的Lac-QDs和具有更柔性糖配体的PEG化（n=3）乳糖-QDs缀合物（LacPEG-QDs）。通过NMR可以确定量子点上糖分子的量，这与TGA测定的结果一致。用ICP-OES测定缀合物的分子式。利用SPR技术研究了量子点与PNA蛋白的相互作用，结果表明，在相同浓度下，乳糖浓度越高，结合亲和力越强，Lac-QDs的结合亲和力比LacPEG-QDs的结合亲和力高。我们进一步使用固相测定来评估Lac-QD和LacPEG-QD在细胞水平上的抗粘附活性。结果表明，Lac-QDs比LacPEG-QDs具有更强的抑制THP 1粘附HUVEC的活性，这与SPR结果一致。我们推测，适当限制糖的柔性可以降低构象熵，从而提高糖基量子点的结合亲和力，这意味着熵变可能是高价糖基量子点与蛋白质相互作用的主要贡献者。乳糖在量子点上的制造提供了一种荧光多价碳水化合物探针，其可以用作糖蛋白的模拟物，用于碳水化合物-蛋白质相互作用和细胞成像的研究。
We have previously reported a facile and convenient method for the preparation of a new type of lactose-CdSeS/ZnS quantum dots conjugates (Lac-QDs) that exhibit biocompatibility, noncytotoxicity and specificity to leukocytes. In order to further study the carbohydrate–protein interactions, a series of Lac-QDs with different lactose densities and a PEGylated (n=3) lactose-QDs conjugate (LacPEG-QDs) with more flexible sugar ligands were prepared. The amount of the sugar molecules on QDs can be determined by NMR, which was in agreement with the results from TGA determination. The formula of the conjugates was determined with ICP-OES. The interactions between the conjugated QDs and the PNA protein were measured using SPR, which revealed that higher lactose density favored binding affinity under the same concentration, and Lac-QDs exhibit higher affinity than LacPEG-QDs. We further used a solid phase assay to assess the anti-adhesion activity of Lac-QDs and LacPEG-QDs on the cell level. The results showed that Lac-QDs had stronger activity in preventing THP1 from adhering to HUVEC than LacPEG-QDs, which was consistent with the SPR results. We reasoned that decrease in the conformational entropy induced by appropriate restriction of sugar flexibility could enhance the binding affinity of glyco-QDs, which implies that entropy change may be the main contributor to the interaction between high valent glyco-QDs and protein. The fabrication of lactose on QDs provides a fluorescent multivalent carbohydrate probe that can be used as mimics of glycoprotein for the study of carbohydrate–protein interactions and cell imaging.