The use of nanomaterials in photodynamic therapy (PDT) has emerged as a promising alternative to enhance the efficacy and overcome the limitations of conventional photosensitizers. A major challenge in this regard is the development of novel cheap, synthetically convenient and biocompatible photoresponsive nanomaterials for visible-light-driven PDT applications. In this work, folate-conjugated titania and alumina nanotubes were successfully prepared and evaluated as novel photoactive nanomaterials with visible light responsiveness. Nanotubes were prepared by hydrothermal synthesis and surface-conjugated with folic acid using a silane coupling agent. Materials were characterized by ATR, TEM, XRD and TGA methods, and their photophysical properties were assessed from diffuse reflectance spectroscopy, production of reactive oxygen species ( 1 O 2 and HO • ) and confocal microscopy fluorescence emission experiments. Our results revealed that folate-conjugated titania and alumina nanotubes are photodynamically active upon irradiation with a blue-LED visible light source, whereas pristine nanotubes or free folic acid exhibits negligible photoresponse under the same experimental conditions. In vitro phototoxicity experiments on HeLa cancer cells confirmed the photodynamic efficacy of folate-conjugated materials as inhibitors of cell proliferation after 1 h of blue-LED light irradiation (450 nm, 100 W m −2 ) in 4 mg/mL solid suspensions. Folate-alumina nanotubes exhibited the highest activity within the nanomaterials under study, which—to the best of our knowledge—constitutes a major advance toward the use of alumina-based nanomaterials in visible-light-driven PDT applications.

中文翻译：

---

用于光动力治疗应用的可见光响应叶酸共轭二氧化钛和氧化铝纳米管

纳米材料在光动力疗法 (PDT) 中的应用已成为提高疗效和克服传统光敏剂局限性的一种有前途的替代方法。这方面的一个主要挑战是开发用于可见光驱动 PDT 应用的新型廉价、合成方便和生物相容性光响应纳米材料。在这项工作中，叶酸共轭二氧化钛和氧化铝纳米管被成功制备并评估为具有可见光响应性的新型光活性纳米材料。纳米管是通过水热合成制备的，并使用硅烷偶联剂与叶酸进行表面共轭。通过 ATR、TEM、XRD 和 TGA 方法对材料进行表征，并通过漫反射光谱评估它们的光物理特性，活性氧（ 1 O 2 和 H2O • ）的产生和共聚焦显微镜荧光发射实验。我们的结果表明，叶酸共轭二氧化钛和氧化铝纳米管在用蓝色 LED 可见光源照射时具有光动力学活性，而原始纳米管或游离叶酸在相同的实验条件下表现出可忽略不计的光响应。对 HeLa 癌细胞的体外光毒性实验证实了在 4 mg/mL 固体悬浮液中，在蓝光 LED 光照射（450 nm，100 W m -2 ）1 小时后，叶酸结合材料作为细胞增殖抑制剂的光动力学功效。叶酸-氧化铝纳米管在所研究的纳米材料中表现出最高的活性，