Photoluminescence Enhancement and Dual-State Emission in Thioflavin T Aggregates Embedded in Nanoporous Anodic Alumina Photonic Crystals Using Micellar Solubilization

Integration of organic light-emitting materials with inorganic optical resonators enables light transmitting, detecting, and processing in a plethora of devices with unusual and exciting properties. Thioflavin T (ThT) was immobilized within the hexagonally arranged nanopores of solid-state platforms using a micellar solubilization approach. Photophysical properties were characterized by fluorescence spectroscopy, UV–vis absorption, femtosecond fluorescence spectroscopy, and nanosecond laser photolysis, revealing that the nanoporous anodic alumina (NAA) photonic environment profoundly alters ThT excited-state relaxation pathways. At millimolar ThT loadings, aggregation-induced electronic coupling was shown to prolong singlet-state lifetimes, promoting intersystem crossing by reducing singlet–triplet splitting. Embedding within the nanopores restricts ThT rotational freedom, enabling fluorescence-phosphoresce dual emission. Multiple internal reflections and scattering within the NAA platform may have a favorable effect on a radiative rate of both singlet and triplet emissions via increasing number of absorbed photons. These findings demonstrate that NAA platforms function as both nanoscale confinement hosts and potential photonic amplifiers, enabling concurrent green fluorescence and orange phosphorescence. The dual-state emission effects could be harnessed for monitoring protein aggregation linked with neurodegenerations after the integration of ThT-stained proteins with NAA platforms.