量子点的表面修饰、表征及其活细胞成像研究

Surface engineering and characterization of quantum dots and its application in living cell imaging

目的通过对疏水性量子点表面进行亲水性改造并偶联单克隆抗体,制备免疫荧光探针用于细胞荧光标记示踪。方法将牛血清白蛋白(BSA)作为乳化剂分子对疏水性量子点进行表面亲水性改造,检测亲水性改造后的量子点物理特性,采用MTT法测定其对细胞活力的影响。将亲水性改造后的量子点与trastuzumab偶联,对HER-2阳性乳腺癌细胞进行实时荧光成像检测。结果经亲水性改造后的量子点粒径约70nm,分布较均一;在不同离子强度和p H环境中,仍保持良好的发光性能和胶体稳定性;生物相容性佳,未检测到明显细胞毒作用;经表面偶联肿瘤特异性单克隆抗体后,成功地对HER-2阳性乳腺癌细胞进行了长时间的活细胞跟踪成像研究。结论亲水性量子点可通过选择性偶联抗体获得免疫量子点荧光探针,从而对细胞、组织等进行特异性荧光成像和检测。

Objective Surface modification of hydrophobic nanoparticles is a key process for their application in the biological medicine fields. The aim of present study is to prepare the immunofluorescent probes by conjugation of hydrophilic surface-engineered quantum dots（QDs） and monoclonal antibody for use of fluorescence labeled cells tracing. Methods The bovine serum albumin（BSA） with excellent water-solubility and biocompatibility was employed as the emulsifying agent, and used for surface modification of hydrophobic QDs under ultrasonication. The diameter, fluorescence spectrum and cytotoxicity of BSAcoated QDs（BSA-tri P.QDs） were analyzed. Then the BSA-coated QDs were conjugated with trastuzumab, which can be recognized and bound specifically to HER2. SKBR-3 breast cancer cells, with over-expression of HER-2, were labeled with hydrophilic QDstrastuzumab and imaged on a fluorescence planar imaging system. Results The experimental results revealed that BSA as the emulsifying agent, combined with other polymers, can effectively phase transfer hydrophobic QDs. The BSA functionalized QDs exhibited excellent colloidal stability with fine hydrodynamic size distribution（about 70nm） in a wide range of p H and ionic strengths values. Moreover, no significant cytotoxic effect was observed in SKBR-3 cells treated with BSA-coated QDs. After being coupled with trastuzumab, the hydrophilic QDs can be used as an immunofluorescence probe for HER2-positive breast cancer cell imaging. Conclusions The advantages of BSA-coated QDs include straight forward synthesis, high colloidal stability, and promising immunofluorescence characteristic when coupled with specific antibody. These are therefore proved to be ideal nano systems for biomedical labeling, targeting, and imaging.