Screening of practically insoluble inorganic materials for luminescence properties and protein binding

Abstract

Persistently luminescent nanocomposites offer a promising platform for both molecular delivery and imaging of biological systems. Although inorganic nanoparticles provide excellent optical properties and traceability, their application is often constrained by concerns over their biodegradability and toxicity.

To address these limitations, we synthesized cation-doped, practically insoluble inorganic compounds with matrices composed of essential elements, using low cost aqueous precipitation method. These materials were systematically evaluated for their X-ray and thermally stimulated luminescence (XRL and TSL) properties. Among the synthesized compounds, CuI and ZnO exhibited XRL activity without detectable TSL, whereas CaCO₃:Mn showed both XRL activity and strong TSL signal. To further assess the potential of CaCO₃:Mn for biomedical use, horseradish peroxidase (HRP) protein-binding tests and luminescence measurements in HRP-PBS suspension were performed. The results demonstrate that CaCO₃:Mn maintains optical properties in protein-rich aqueous environments, highlighting its potential as a luminescent sensor or tracking agent in biological systems.