Multifunctional Silica-Based Optical Nanoparticles with Aqueous-Phase Multicolor Room-Temperature Phosphorescence and Structural Color

Abstract

Developing organic−inorganic hybrid nanomaterials generating multiple optical signals remains challenging due to inherent design complexities. Herein, we present organic-SiO2 nanohybrids exhibiting size-dependent room-temperature phosphorescence (RTP) and structural color. By employing a covalent anchoring strategy, silanized organic phosphors are incorporated into the SiO2 matrix, protecting triplet excitons and enabling multicolor aqueous RTP emission with a maximum lifetime of 314.81 ms. Notably, as particle size increases, organic-SiO2 RTP nanohybrids exhibit an approximately 2-fold enhancement in RTP lifetime and generate a red-shifted structural color signal through self-assembly. The long-lived luminescence and excellent biocompatibility of NPA@SiO2 (H-120) enable in vivo afterglow imaging without additional covering treatments. Within 0.5 h after tail vein injection at an ultralow chromophore dose (0.25 mg kg−1), tumor sites in mice are precisely localized via efficient cellular uptake, representing superior imaging performance. Furthermore, the unique multiplexed optical features of organic-SiO2 nanohybrids provide significant advantages for anti-counterfeiting labeling and multi-level encryption applications.