Evaluating the Biocompatibility and Toxicological Profile of Luminescent Calcium-Based Micro- and Nanomaterials

Abstract

Synthesis and characterization of calcium-based materials (CBMs) such as calcium pyrophosphate and hydroxyapatite activated with Er(III)–Yb(III) and Eu(III), respectively, are reported to establish their utility as markers for dosimetry and biological imaging. Under 980 and 246 nm excitation, these phosphors produce distinct emissions through ²H_11/2 to ⁴I_15/2 and ⁵D₀ to ⁷F₄ Er(III) and Eu(III) transitions, respectively. Despite the promising optical performance of these materials, there is a notable lack of toxicological data regarding lanthanides such as Er(III), Yb(III), and Eu(III) when utilized as dopants. To address this knowledge gap, a chronic toxicity study was performed by using the Daphnia magna model at 300 mg/L. The results indicate that although CBMs do not cause significant mortality, they can produce significant physiological changes, such as delaying sexual maturity from 9.6 to 13 days and reducing the number of neonates per female (around 50%) in the Eu(III)-doped samples (the most critical case). Survival rates also showed a decrease, from 95% to near 70%, in doped hydroxyapatite. These findings suggest that CBMs are suitable for biomedical applications because they cannot produce either highly toxic or fatal effects at these levels. Nevertheless, their eventual implementation could require careful concentration management to protect the organism’s suitability. This work provides an assessment of the environmental impact of these dopants and supports their responsible integration into future device development and diagnostic biological imaging applications.