Tokyo Institute of Technology, School of Materials and Chemical Technology, Department of Materials Science and Engineering, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Colloids Surf B Biointerfaces. 2024 Jul;239:113975. doi: 10.1016/j.colsurfb.2024.113975. Epub 2024 May 16.
Early and accurate cancer diagnosis is crucial for improving patient survival rates. Luminescent nanoparticles have emerged as a promising tool in fluorescence bioimaging for cancer diagnosis. To enhance diagnostic accuracy, ligands promoting endocytosis into cancer cells are commonly incorporated onto nanoparticle surfaces. Folic acid (FA) is one such ligand, known to specifically bind to folate receptors (FR) overexpressed in various cancer cells such as cervical and ovarian carcinoma. Therefore, surface modification of luminescent nanoparticles with FA can enhance both luminescence efficiency and diagnostic accuracy. In this study, luminescent europium-doped hydroxyapatite (EuHAp) nanocrystals were prepared via hydrothermal method and subsequently modified with (3-Aminopropyl)triethoxysilane (APTES) followed by FA to target FR-positive human cervical adenocarcinoma cell line (HeLa) cells. The sequential grafting of APTES and then FA formed a robust covalent linkage between the nanocrystals and FA. Rod-shaped FA-modified EuHAp nanocrystals, approximately 100 nm in size, exhibited emission peaks at 589, 615, and 650 nm upon excitation at 397 nm. Despite a reduction in photoluminescence intensity following FA modification, fluorescence microscopy revealed a remarkable 120-fold increase in intensity compared to unmodified EuHAp, attributed to the enhanced uptake of FA-modified EuHAp. Additionally, confocal microscope observations confirmed the specificity and the internalization of FA-modified EuHAp nanocrystals in HeLa cells. In conclusion, the modification of EuHAp nanocrystals with FA presents a promising strategy to enhance the diagnostic potential of cancer bioimaging probes.
早期和准确的癌症诊断对于提高患者的生存率至关重要。荧光生物成像中，发光纳米粒子已成为一种有前途的工具，可用于癌症诊断。为了提高诊断准确性，通常将促进内吞作用进入癌细胞的配体结合到纳米粒子表面。叶酸（FA）就是这样一种配体，已知其特异性结合在各种癌细胞（如宫颈癌和卵巢癌）中过度表达的叶酸受体（FR）上。因此，通过 FA 对发光纳米粒子进行表面修饰可以提高发光效率和诊断准确性。在这项研究中，通过水热法制备了发光的 Eu 掺杂羟基磷灰石（EuHAp）纳米晶，然后用（3-氨丙基）三乙氧基硅烷（APTES）进行修饰，随后再用 FA 修饰，以靶向 FR 阳性的人宫颈腺癌细胞系（HeLa）细胞。APTES 和 FA 的顺序接枝在纳米晶和 FA 之间形成了牢固的共价键。尺寸约为 100nm 的棒状 FA 修饰的 EuHAp 纳米晶在 397nm 激发下表现出 589、615 和 650nm 的发射峰。尽管 FA 修饰后光致发光强度降低，但荧光显微镜显示，与未修饰的 EuHAp 相比，强度显著增加了 120 倍，这归因于 FA 修饰的 EuHAp 的摄取增强。此外，共聚焦显微镜观察证实了 FA 修饰的 EuHAp 纳米晶在 HeLa 细胞中的特异性和内化。总之，用 FA 修饰 EuHAp 纳米晶为增强癌症生物成像探针的诊断潜力提供了一种很有前途的策略。
