CAIX 适配体功能化靶向纳米气泡用于各种肿瘤的超声分子成像。

PURPOSE: Targeted nanobubbles can penetrate the tumor vasculature and achieve ultrasound molecular imaging (USMI) of tumor parenchymal cells. However, most targeted nanobubbles only achieve USMI of tumor parenchymal cells from one organ, and their distribution, loading ability, and binding ability in tumors are not clear. Therefore, targeted nanobubbles loaded with carbonic anhydrase IX (CAIX) aptamer were fabricated for USMI of various tumors, and the morphological basis of USMI with targeted nanobubbles was investigated. MATERIALS AND METHODS: The specificity of CAIX aptamer at the cellular level was measured by immunofluorescence and flow cytometry. Targeted nanobubbles loaded with CAIX aptamer were prepared by a maleimidethiol coupling reaction, and their binding ability to CAIX-positive tumor cells was analyzed in vitro. USMI of targeted and non-targeted nanobubbles was performed in tumor-bearing nude mice. The distribution, loading ability, and binding ability of targeted nanobubbles in xenograft tumor tissues were demonstrated by immunofluorescence. RESULTS: CAIX aptamer could specifically bind to CAIX-positive 786-O and Hela cells, rather than CAIX-negative BxPC-3 cells. Targeted nanobubbles loaded with CAIX aptamer had the advantages of small size, uniform distribution, regular shape, and high safety, and they could specifically accumulate around 786-O and Hela cells, while not binding to BxPC-3 cells in vitro. Targeted nanobubbles had significantly higher peak intensity and larger area under the curve than non-targeted nanobubbles in 786-O and Hela xenograft tumor tissues, while there was no significant difference in the imaging effects of targeted and non-targeted nanobubbles in BxPC-3 xenograft tumor tissues. Immunofluorescence demonstrated targeted nanobubbles could still load CAIX aptamer after penetrating the tumor vasculature and specifically binding to CAIX-positive tumor cells in xenograft tumor tissues. CONCLUSION: Targeted nanobubbles loaded with CAIX aptamer have a good imaging effect in USMI of tumor parenchymal cells, and can improve the accuracy of early diagnosis of malignant tumors from various organs.

目的：靶向纳米气泡可以穿透肿瘤血管，并实现肿瘤实质细胞的超声分子成像（USMI）。然而，大多数靶向纳米气泡只能实现来自一个器官的肿瘤实质细胞的 USMI，并且它们在肿瘤中的分布、载药能力和结合能力尚不清楚。因此，制备了负载碳酸酐酶 IX（CAIX）适体的靶向纳米气泡，用于各种肿瘤的 USMI，并研究了靶向纳米气泡进行 USMI 的形态学基础。

材料和方法：通过免疫荧光和流式细胞术测量 CAIX 适体在细胞水平上的特异性。通过马来酰亚胺硫醇偶联反应制备负载 CAIX 适体的靶向纳米气泡，并分析其与 CAIX 阳性肿瘤细胞的结合能力。在荷瘤裸鼠中进行靶向和非靶向纳米气泡的 USMI。通过免疫荧光证明了靶向纳米气泡在异种移植肿瘤组织中的分布、载药能力和结合能力。

结果：CAIX 适体可以特异性结合 CAIX 阳性的 786-O 和 Hela 细胞，而不是 CAIX 阴性的 BxPC-3 细胞。负载 CAIX 适体的靶向纳米气泡具有粒径小、分布均匀、形态规则和安全性高的优点，可以特异性地聚集在 786-O 和 Hela 细胞周围，而在体外不与 BxPC-3 细胞结合。在 786-O 和 Hela 异种移植肿瘤组织中，靶向纳米气泡的峰值强度和曲线下面积均显著高于非靶向纳米气泡，而在 BxPC-3 异种移植肿瘤组织中，靶向和非靶向纳米气泡的成像效果无显著差异。免疫荧光显示，靶向纳米气泡穿透肿瘤血管后仍能负载 CAIX 适体，并特异性结合异种移植肿瘤组织中的 CAIX 阳性肿瘤细胞。

结论：负载 CAIX 适体的靶向纳米气泡在肿瘤实质细胞的 USMI 中具有良好的成像效果，可提高对来自不同器官的恶性肿瘤的早期诊断准确性。