Design of Halloysite Nanotube-Based Nanomaterials for Theranostic Applications: Fluorescent Probes and Chemodynamic Activity

Abstract

The development of theranostic systems is of fundamental importance for the treatment of diseases. These systems should combine the features of fluorescent molecules that can act as diagnostic systems and species which can exert therapeutic activity. Herein we report the synthesis of multifunctional halloysite nanotubes (HNTs) based nanomaterial obtained by the covalent modification of the clay external surface with an halochromic probe and the immobilization of Fe3O4 nanoparticles (HNTs-1@Fe3O4) capable to exert chemodynamic activity. The covalent modification of HNTs was performed by two different synthetic approaches and the best strategy was evaluated by estimating the degree of functionalization of the clay by thermogravimetric analysis. The synthetized nanomaterial was thoroughly characterized and its photoluminescence properties upon different conditions i.e. different solvents, pH and temperatures, were also studied. The HNTs-1@Fe3O4 nanomaterial was found to exhibit good peroxidase-like activity as shown by testing it in the catalytic oxidation of the colorless enzyme substrate 3,3’,5,5’-tetramethylbenzidine (TMB) to blue TMB oxide (ox-TMB) in the presence of H2O2. This work highlights the usefulness of the covalent approach to modify halloysite surfaces to generate nanomaterials for potential tissue imaging under different stimuli. In addition, the combination with Fe3O4NPs led to the synthesis of multifunctional materials with potential use as theranostic system for treatment of diseases.