Biodegradable rare earth fluorochloride nanocrystals for phototheranostics

Area of Science:

• Biomedical Engineering
• Materials Science
• Nanotechnology

Background:

• Rare earth (RE) doped inorganic nanocrystals show promise for deep tissue shortwave-infrared (SWIR) imaging and early tumor detection.
• Concerns exist regarding the long-term toxicity and biocompatibility of traditional inorganic nanocrystals.

Purpose of the Study:

• To design and synthesize biodegradable rare earth nanocrystals for enhanced SWIR imaging and cancer therapy.
• To address the limitations of inorganic nanocrystals by developing a rapidly degradable alternative.

Main Methods:

• Synthesized neodymium-doped strontium fluorochloride (SrFCl:Nd) nanocrystals, utilizing a chlorinated host for improved SWIR brightness.
• Coated SrFCl:Nd nanoparticles with polydopamine (PDA) to create SrFCl:Nd@PDA nanoparticles with near-infrared absorption.
• Evaluated the degradation profile, imaging capabilities, and in vivo behavior of the nanoparticles.

Main Results:

• SrFCl:Nd@PDA nanoparticles exhibited enhanced brightness in the SWIR region due to the low phonon energy of the SrFCl host.
• The nanoparticles functioned as effective contrast agents for photoacoustic imaging and as photothermal agents for cancer therapy.
• Complete degradation of SrFCl:Nd@PDA nanoparticles was observed within 1 hour in phosphate buffer solution.
• Demonstrated increased accumulation and retention at tumor sites with complete in vivo clearance approximately 6 hours post-injection.

Conclusions:

• SrFCl:Nd@PDA nanoparticles represent a promising biodegradable phototheranostic agent for early tumor detection and therapy.
• The rapid degradation effectively mitigates concerns associated with long-term accumulation and potential toxicity.
• These findings pave the way for safer and more effective nanomedicine applications in oncology.