目的：研制一种生物素-亲和素系统（BAS）介导叶酸受体（FR）靶向量子点（QD）荧光探针，初步验证其靶向性及信号放大效应。方法：采用活泼酯法，将链霉亲和素（SA）与QD共价偶联制备QD-SA并对其物理特性进行验证；采用活泼酯法以牛血清蛋白为载体合成生物素化叶酸（FA）。通过生物素化FA与QD-SA结合制备BAS介导叶酸受体（FR）靶向QD探针，比较该探针对卵巢癌SKOV3细胞及FR表达阴性的肺癌A549细胞的识别情况，并验证其靶向特异性；对比该探针在生物素化FA孵育1、4 h时成像的效果；比较该探针与未经BAS介导的QD-FA探针在不同孵育时间对卵巢癌SKOV3细胞成像的差异。结果：BAS介导FR靶向QD探针可特异性识别FR表达阳性的卵巢癌SKOV3细胞，且孵育4 h较1 h荧光信号明显增强，同等条件下其产生的荧光强度较未经BAS介导的QD-FA探针明显增强。结论：制备了一种特异性好、灵敏度高的BAS介导FR靶向QD探针，该探针在卵巢癌早期诊断方面具有潜在应用价值。%Objective:To develop a biotin-streptavidin system (BAS)-mediated folate receptor (FR)-targeted quantum dot (QD) fluorescent probe and preliminarily validate the targeting ability and signal amplification effect of the probe. Methods: Streptavidin (SA) was covalently coupled with QD through the active ester method;the physical characteristics of the prepared QD-SA were veri-fied. Biotinylated folate was synthesized through the carrier bovine serum albumin using the same method and then reacted with QD-SA to form the special probe. The probe was used to identify SKOV3 cells and FR-negative A549 cells to verify its targeting speci-ficity. QD-SA was used as the contrast. SKOV3 cells were imaged using the BAS-mediated FR-targeted QD probe with a biotinylated folate incubation time of 1 or 4 h. Various reaction times were also tested between the probe and the QD-FA that was formed without BAS mediation. Results:The BAS-mediated FR-targeted QD probe specifically recognized FR-positive SKOV3 cells. The probe ob-tained higher fluorescent intensity after 4 h than after 1 h of biotinylated folate incubation. The BAS-mediated FR-targeted QD probe al-so had a stronger fluorescent signal than the QD-FA probe. Conclusion:The proposed probe presents a great potential in the early diag-nosis of ovarian cancer because of its high specificity and sensitivity.
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