TADF-Emitting Nanoparticles for Application as Probes in Time-Resolved Imaging and 1O2 Photosensitizers

Abstract

Organic Thermally Activated Delayed Fluorescence (TADF) molecules are luminescent compounds capable of harvesting energy from triplet states without using heavy metals. This process results in oxygen-sensitive, long-lived delayed emission, suitable for developing optical probes for time-gated cell imaging, oxygen sensors, and singlet oxygen photosensitizers. Despite their potential, the use of TADF emitters in these applications is hindered by poor performance in polar media and the challenge of balancing high photoluminescence quantum yields, long emission lifetimes, and high triplet formation quantum yields. In this study, novel TADF emitters are developed based on 1,8-naphthalimide (NI) dyes, and how encapsulation in polymeric nanoparticles can enhance their performance in aqueous media is demonstrated. The resulting nanomaterials exhibit high delayed-to-prompt emission ratios, long delayed fluorescence lifetimes, and exceptional applicability in time-resolved imaging. The singlet oxygen photosensitization capabilities of the TADF nanomaterials in the photodegradation of phenol, exploring a Förster Resonance Energy Transfer (FRET) system that improved the efficiency, are also assessed. These findings highlight the promising potential of TADF nanomaterials for diverse applications, including photodegradation of pollutants, cellular imaging, and biosensing.