Novel Dy³⁺-Doped TiO₂ Nanoparticles Exhibit Unique Luminescent Properties with Promising Biomedical Applications

A recent study conducted by researchers from Kannur University and Anand Niketan College of Science, Arts, and Commerce developed new nanomaterials that could be used for biomedical applications. These nanomaterials, which were based on dysprosium (Dy³⁺)-doped titanium dioxide (TiO₂), were designed to offer a combination of structural, morphological, and photoluminescent characteristics to make them ideal for applications in imaging, sensing, and pharmacological products (1,2). The findings of this study were published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (1).

In this study, which was led by Shruti P. Dhale, Nilesh S. Ugemuge, and K. M. Nissamudeen, marks a significant advance in nanomaterials science, particularly in the exploration of rare-earth-doped semiconductors (1). The research team prepared pristine and Dy³⁺-doped TiO₂ nanoparticles with a uniform morphology and well-controlled particle size between 7–9 nm. One of the changes they made to prepare nanoparticles that made this study unique was using ethylene glycol as a solvent, which is normally not used in hydrothermal synthesis (1). The nanoparticles’ size developed in the study fell within the quantum dot category, making the material especially appealing for use in biomedical applications such as targeted drug delivery and cellular imaging (1).

Visualization of Lipid Nanoparticles in Delivery Systems. Generated by AI. | Image Credit: © Aniwat - stock.adobe.com

To test the synthesized material, the researchers used X-ray diffraction (XRD) analysis. The successful incorporation of Dy³⁺ ions into the TiO₂ lattice was evident in both the XRD and Raman spectroscopy data, with the latter revealing key insights into the vibrational modes of the doped material and its influence on phase stability (1).

Then, the research team used scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) to further characterize the spherical morphology and elemental composition of the nanoparticles (1). Importantly, the polar nature of ethylene glycol played a crucial role in stabilizing the TiO₂ particles, preventing agglomeration and ensuring consistent nucleation (1). Agglomeration and nucleation consistency are two factors that significantly impact the material’s performance and scalability (1).

There were a couple of important takeaways in this study. The first was the photoluminescence (PL) behavior of the Dy³⁺-doped TiO₂ nanoparticles. Although dysprosium is traditionally known to emit sharp luminescence lines in the blue (480 nm), yellow (575 nm), and red (670 nm) spectral regions because of its 4f–4f transitions, this study observed an intense and singular broad emission peak at 575 nm under 450 nm excitation (1). This was an unusual luminescence pattern due to the incorporation of Dy³⁺ ions in a low-symmetry local site within the TiO₂ lattice (1). The reason for this pattern change was because of the crystal field distortions and the presence of oxygen vacancies introduced during the doping process (1).

The oxygen vacancies were also an important note in this study. The researchers showed that these vacancies influenced the optical properties of the nanomaterial by modifying the local crystal field and creating localized states within the bandgap. These states can trap excited charge carriers, thereby altering emission characteristics and leading to the broadening or quenching of certain photoluminescent lines (1). When the Dy³⁺-doped TiO₂ was dispersed in ethanol and exposed to UV–visible light, the photoluminescence intensity increased significantly, which demonstrates that these nanoparticles can potentially be effective in imaging and sensing platforms (1).

The researchers also reported that the bandgap energy of the 2 wt% Dy³⁺-doped anatase TiO₂ was approximately 3.2 eV and supportive of its photoactive properties under UV irradiation (1).

By synthesizing these luminescent nanoparticles using a relatively eco-friendly and low-toxicity solvent like ethylene glycol, the researchers proposed a new production method for nanoparticles that is more sustainable. Moreover, the quantum-dot-sized particles suggest practical applications in nanomedicine, particularly in drug delivery systems where particle size and stability are critical factors (1).

In conclusion, this study not only advances our understanding of rare-earth-doped TiO₂ systems, but it also opens up new directions in the design of multifunctional nanomaterials with tailored optical properties for biomedical and environmental technologies (1).

References

1. Greeshma, K.; Adiyodi, A. K.; Ancy, S. S.; et al. Synthesis and Spectroscopic Analysis of TiO₂:Dy³⁺ Phosphor for Optical and Pharmaceutical Applications. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2025, 337, 126086. DOI: 10.1016/j.saa.2025.126086
2. Dhale, S.; Ugemuge, N.; Singh, V. S. Study of Luminescence Behavior in Dy³⁺-Activated Ba₃Ca₂(PO₄)₃F. J. Electron. Mater. 2024, 53, 5926–5936. DOI: 10.1007/s11664-024-11152-3