An ultra-sensitive dual-mode imaging system using metal-enhanced fluorescence in solid phantoms

Area of Science:

• Biomedical Imaging
• Nanotechnology
• Optical Physics

Background:

• Gold nanoparticles (GNPs) offer unique optical properties for bioimaging applications.
• Developing sensitive imaging systems for GNPs in complex environments remains a challenge.
• Dual modal imaging can overcome limitations of single-modality techniques.

Purpose of the Study:

• To develop and validate a highly sensitive dual modal imaging system for GNPs.
• To investigate the influence of fluorophore conjugation on GNP imaging signals.
• To enable both surface and deep tissue imaging of GNPs.

Main Methods:

• Developed a dual modal imaging system integrating fluorescence lifetime imaging microscopy (FLIM) and diffusion reflection (DR).
• Utilized metal enhanced fluorescence (MEF) to amplify optical signals.
• Tested gold nanospheres (GNS) and gold nanorods (GNRs) conjugated with various fluorophores in solution and solid phantoms.

Main Results:

• Observed fluorescence quenching with Fluorescein (excitation < SPR) and enhanced fluorescence with Rhodamine B and Sulforhodamine B (excitation within SPR).
• FLIM confirmed enhanced fluorescence in solution and solid phantoms.
• DR successfully detected GNRs in phantoms via light scattering changes at specific wavelengths.

Conclusions:

• The developed dual modal imaging system demonstrates high sensitivity for detecting GNPs.
• MEF significantly enhances fluorescence signals when fluorophore excitation aligns with GNP SPR.
• This technique provides efficient molecular and functional imaging capabilities for GNPs.