Dye-sensitized upconversion nanoparticles with enhanced aqueous luminescence for neuronal imaging

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Organic dyes and upconversion nanoparticles (UCNPs) enhance near-infrared (NIR) excited luminescence.
• Surface functionalization of UCNPs improves signal-to-noise ratio and bioimaging resolution.

Purpose of the Study:

• To develop a heptamethine cyanine derivative (IR61-BF) for dye-sensitized UCNPs.
• To enhance luminescence efficiency of UCNPs in aqueous solutions through molecular modification.

Main Methods:

• Synthesized core-shell UCNPs (NaYF4:YbTm@NaYF4:YbNd) via high-temperature decomposition.
• Introduced a difluorobenzene group into the cyanine structure of NIR dye IR61 to create IR61-BF.
• Coated UCNPs with DSPE-PEG and incorporated IR61-BF for enhanced sensitization.

Main Results:

• Nd3+ ions in UCNPs efficiently sensitized NIR light absorption at 808 nm.
• The difluorobenzene group in IR61-BF significantly increased dye quantum yield and UCNP sensitization.
• Achieved a 167.1-fold enhancement in upconversion luminescence in aqueous phase.

Conclusions:

• The novel IR61-BF dye effectively sensitizes UCNPs, especially in aqueous environments.
• Demonstrated biocompatibility for neuronal imaging and potential for retrograde intra-neuronal delivery.
• Optimized dye-UCNP combination offers superior performance for bioimaging applications.