A specific HeLa cell-labelled and lysosome-targeted upconversion fluorescent probe: PEG-modified Sr₂YbF₇:Tm³⁺ 

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Upconversion nanoparticles (UCNs) offer unique optical properties for bioimaging.
• Developing water-soluble UCNs with targeted capabilities is crucial for biomedical applications.
• Strontium ytterbium fluoride (Sr2YbF7) doped with thulium (Tm3+) is a promising UCN material.

Purpose of the Study:

• To synthesize water-soluble PEG-modified Sr2YbF7:Tm3+ nanoparticles.
• To investigate their optical properties and potential for bioimaging.
• To evaluate their biocompatibility, cell targeting, and photostability for cancer diagnosis.

Main Methods:

• One-pot solvothermal synthesis of Sr2YbF7:Tm3+ nanoparticles.
• Polyethylene glycol (PEG) modification for water solubility.
• Characterization of optical emission spectra under 980 nm excitation.
• In vitro biological experiments using HeLa cells and mouse embryonic fibroblasts.

Main Results:

• Optimized red-light emission (677-699 nm) achieved with 0.7% Tm3+ doping.
• PEG-modified nanoparticles exhibited low toxicity and excellent cell membrane permeability.
• High photostability demonstrated under irradiation.
• Successful differentiation between HeLa cells and mouse embryonic fibroblasts.
• Targeted accumulation within lysosomes of HeLa cells.

Conclusions:

• Water-soluble PEG-modified Sr2YbF7:Tm3+ nanoparticles were successfully synthesized.
• The nanoparticles possess desirable optical and biological properties for bioimaging.
• These UCNs show potential as a diagnostic tool for cancer detection, specifically targeting lysosomes.