Nd³⁺ sensitized dumbbell-like upconversion nanoparticles for photodynamic therapy application

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Near-infrared excited upconversion nanoparticles (UCNPs) offer advantages for bioapplications due to better tissue penetration and reduced overheating.
• Developing efficient UCNPs for photodynamic therapy (PDT) is crucial for cancer treatment.

Purpose of the Study:

• To fabricate dumbbell-like structured NaYF4:Yb/Er@NaNdF4:Yb nanoparticles.
• To investigate their application in photodynamic therapy (PDT) upon 808 nm laser excitation.
• To compare their PDT efficacy with other UCNP structures.

Main Methods:

• Fabrication of dumbbell-like NaYF4:Yb/Er@NaNdF4:Yb UCNPs via epitaxial growth.
• Characterization of UCNP structure and upconversion luminescence (UCL) properties.
• Evaluation of singlet oxygen generation and cancer cell killing efficacy under 808 nm laser irradiation.

Main Results:

• Dumbbell-like UCNP structure formation attributed to epitaxial growth and structure mismatch.
• Optimized Nd3+ doping (90%) enhances UC emission intensity by partially inhibiting Er3+ to Nd3+ energy back-transfer.
• Dumbbell-like UCNPs demonstrated superior singlet oxygen generation and cancer cell killing in PDT compared to core-shell and core-shell-shell UCNPs, despite lower UCL intensity.

Conclusions:

• The dumbbell-like UCNP structure provides a strategy to balance UCL and Förster Resonance Energy Transfer (FRET) efficiencies for enhanced PDT.
• This approach shows potential for improved therapeutic effects in cancer therapy.
• The findings highlight the importance of nanostructure design for optimizing UCNP-based photodynamic therapy.