Two-Photon Supramolecular Nanoplatform for Ratiometric Bioimaging

Area of Science:

• Biomedical imaging
• Supramolecular chemistry
• Nanotechnology

Background:

• Two-photon fluorescent imaging offers greater tissue penetration than one-photon methods for biomedical research.
• High laser power in two-photon imaging can cause photobleaching and photodamage, limiting in vivo applications.
• Developing advanced probes is crucial for overcoming these limitations in deep tissue imaging.

Purpose of the Study:

• To create a sensitive and selective two-photon excited nanoprobe (TPFN) for biomedical imaging.
• To utilize supramolecular host-guest chemistry for enhanced probe performance.
• To enable accurate ratiometric imaging of reactive oxygen species, specifically hydrogen peroxide (H2O2), in deep tissues.

Main Methods:

• Supramolecular host-guest complexation was employed to assemble the TPFN.
• The TPFN's fluorescence intensity amplification and detection limits for H2O2 were evaluated.
• Ratiometric fluorescent imaging was performed using the TPFN in biological samples, comparing one-photon and two-photon excitation.
• In vivo imaging of deep liver tissues was conducted to assess penetration depth.

Main Results:

• The TPFN demonstrated significant fluorescence amplification (21-fold) compared to free guest molecules.
• A highly sensitive detection limit for H2O2 (0.127 μM) was achieved, significantly lower than free molecules (11.98 μM).
• Ratiometric imaging with TPFN provided accurate intracellular H2O2 analysis by correcting for internal references.
• Two-photon excitation with TPFN enabled deeper tissue penetration for H2O2 visualization in liver tissues compared to one-photon excitation.

Conclusions:

• The developed TPFN, based on supramolecular assembly, offers superior sensitivity, selectivity, and biocompatibility for H2O2 detection.
• TPFN facilitates enhanced fluorescence intensity and enables ratiometric imaging for accurate biological analysis.
• The nanoprobe's ability to image deeper tissues via two-photon excitation makes it a powerful tool for in vivo biomedical research.