Halloysite Nanotubes Functionalized with Naphthalene Diimide and Peptide Nucleic Acid Derivatives: Toward Multifunctional Nanomaterials

The development of multifunctional nanomaterials is an area of growing interest, particularly for systems that integrate optical and molecular recognition capabilities. Halloysite nanotubes (HNTs) provide a versatile platform for functionalization owing to their unique tubular structure and distinct inner and outer surface chemistry. In this study, we report the synthesis and characterization of HNTs-based nanomaterials functionalized with naphthalene diimide derivatives (NDIs) and peptide nucleic acid (PNA). NDIs were covalently anchored onto the external surface of HNTs to enhance their solubility and photophysical properties, while a model PNA sequence was incorporated to explore the suitability of NDI-functionalized HNTs as an efficient platform for the delivery of molecular probes. The synthesized nanomaterial was thoroughly characterized through morphological (HAADF/STEM), spectroscopic (UV–vis, fluorescence, FT-IR), and thermal (TGA) analyses. The results confirm the successful functionalization of HNTs, demonstrating the tunability of their optical properties and the effective integration of the PNA. This study provides insights into the engineering of hybrid nanomaterials with potential applications in molecular recognition, sensing, and advanced material design.