Eu3+ activated gadolinium oxide quantum dots: Biocompatible red luminescent phosphor for photonic, latent fingerprint imaging, and anticancer therapy

Abstract

In this study, we employed a straightforward chemical reduction method to synthesize Gd2O3 quantum dots (QDs) doped with Eu3+ ions, yielding a remarkable red emission. X-ray diffraction (XRD) analysis confirmed the cubic structure of both pristine and Eu3+ doped Gd2O3 QDs. Characterization of particle size and elemental composition was accomplished through Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence analysis under UV excitation revealed a blue emission at 436 nm for the undoped Gd2O3 QDs. Furthermore, room temperature photoluminescence analysis was conducted on the undoped Gd2O3 quantum dots (QDs) with a UV excitation source. While Gd2O3 QDs emitted a blue light at 436 nm under 396 nm illumination, the Eu3+ doped Gd2O3 QDs exhibited a striking red luminescence under the same 394 nm wavelength. The red luminescence was notably enhanced in Gd2O3 QDs containing 0.5 mol% Eu3+ ions, although concentration quenching was observed when the concentration exceeded this level. A transfer of energy from pristine Gd2O3 QDs to Eu3+ ions was observed, leading to color purity exceeding 80.8% in the optimized sample. Notably, the 0.5 mol% Eu3+-doped Gd2O3 QD phosphor displayed non-cytotoxicity on C2C12 muscle myoblast cells while demonstrating remarkable cytotoxicity against MDA-MB-231 human breast cancer cells. This versatile material holds great promise for applications in latent fingerprinting, security coding, labeling, anticancer therapies, bio-imaging, and the advancement of lanthanide-doped QD phosphors for a wide range of photonic and biomedical applications.