Engineering halloysite-BODIPY nanomaterials: a platform for intracellular glutathione detection and potential photodynamic therapy.

The design and development of nanomaterials that combine the properties of fluorescent molecules with those of valuable carrier systems, such as clay minerals, represent a promising approach for the synthesis of nanoplatforms for theranostic applications. Herein, we report the covalent modification of the external surface of halloysite nanotubes (HNTs) with two different BODIPY derivatives, Bdpy1 and Bdpy2. These derivatives were designed through modification of the BODIPY core to develop glutathione (GSH) sensors and photosensitizers for photodynamic therapy (PDT). The experimental conditions for their synthesis were optimized, and comprehensive physicochemical characterization confirmed the successful HNT functionalization. The resulting nanomaterials preserve the intrinsic photophysical properties of BODIPY derivatives, while exhibiting bathochromically shifted absorption/emission profiles and reduced HOMO-LUMO energy gaps, indicative of grafting onto the rigid halloysite framework. The HNTs-Bdpy1 nanomaterial proved to be a promising sensor for GSH, as demonstrated by biological studies on HepG2 cell lines, which were used as a model of cells with high intracellular GSH levels. Conversely, HNTs-Bdpy2 demonstrated efficient singlet oxygen generation under λ = 532 nm irradiation and enhanced resistance to photobleaching, highlighting its potential for application in future photodynamic therapy. Overall, this approach offers a versatile and robust platform that bridges nanotechnology and photochemistry, paving the way for multifunctional systems capable of simultaneous imaging, sensing, and therapeutic applications in biomedicine.