As a liquid biopsy, circulating tumor cells (CTCs) have great significance for the early diagnosis, timely treatment, and practical evaluation of metastasis or recurrence of cancer. However, the enrichment of rare CTCs in complex blood samples is still a significant challenge. Here, unique and highly sensitive folic acid (FA)-functionalized cascade amplification system-modified magnetic nanoparticles (MNPs) were constructed to effectively capture CTCs in whole blood. In this system, as a targeted molecule, numerous FA molecules were conjugated on the surface of PAMAM dendrimers (PAMAM-FA) (first amplification) through a polyethylene glycol (PEG) linker, which could promote the more facile binding of folate receptors (FR) on the surface of ovarian cancer cells (SKOV3 cells). Then, PAMAM-FA was further modified with biotin to fabricate biotin-PAMAM-FA (BPF), which could combine with streptavidin (SA)-modified MNPs (SMs) via the SA-biotin system to efficiently target and separate CTCs. The capture efficiency of the constructed MNPs-SA ∼ biotin-PAMAM-FA (SM@BPF) nanoprobes was 90.3% with high cell viability (∼93.2%) and minimal non-specific adsorption (∼25%). Moreover, fewer nanoprobes were absorbed on the surface of the SM@BPF-captured SKOV3 cells (one-step method) compared with the SM/BPF-captured SKOV3 cells (two-step method), which was beneficial for further biological analysis. We expect that this recognition molecule-based cascade amplification system will provide an innovative CTCs enrichment platform for the early-stage diagnosis of ovarian cancer.

中文翻译：

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通过PAMAM树状大分子/ SA-生物素介导的级联扩增系统对叶酸官能化的磁性纳米探针进行有效富集循环肿瘤细胞

作为一种液体活检，循环肿瘤细胞（CTC）对于癌症的早期诊断，及时治疗和转移或复发的实用评估具有重要意义。但是，复杂血液样品中稀有CTC的富集仍然是一个重大挑战。在这里，构建了独特且高度敏感的叶酸（FA）功能化的级联扩增系统修饰的磁性纳米颗粒（MNP），以有效捕获全血中的CTC。在该系统中，作为目标分子，许多FA分子通过聚乙二醇（PEG）接头共轭在PAMAM树状大分子（PAMAM-FA）的表面上（首次扩增），这可以促进叶酸受体（FR）的更容易结合）在卵巢癌细胞（SKOV3细胞）的表面上。然后，通过SA生物素系统有效地靶向和分离四氯化碳。所构建的MNPs-SA〜生物素-PAMAM-FA（SM @ BPF）纳米探针的捕获效率为90.3％，具有高细胞活力（〜93.2％）和最小的非特异性吸附（〜25％）。此外，与SM / BPF捕获的SKOV3细胞（两步法）相比，SM @ BPF捕获的SKOV3细胞（一步法）吸收的纳米探针更少，这有利于进一步的生物学分析。我们希望这种基于识别分子的级联扩增系统将为卵巢癌的早期诊断提供一个创新的CTC富集平台。