Molecular Imaging Cellular SPIO Uptake with Nonlinear Optical Microscopy

Area of Science:

• Biomedical imaging
• Nanotechnology
• Cell biology

Background:

• Super paramagnetic iron oxide (SPIO) nanoparticles are used in biomedical imaging and drug delivery.
• Understanding nanoparticle-cell interactions is crucial for optimizing their therapeutic and diagnostic applications.
• The reticuloendothelial system (RES) is a key site for SPIO nanoparticle uptake.

Purpose of the Study:

• To develop and demonstrate a novel method for visualizing the selective binding of lipids to SPIO nanoparticles within RES cells.
• To investigate the specific interactions between SPIO nanoparticles and lipid molecules in Kupffer cells and spleen melanomacrophages.

Main Methods:

• Utilized surface-enhanced coherent anti-Stokes Raman scattering (SECARS) microscopy for high-resolution vibrational microspectroscopy.
• Experimentally injected SPIO nanoparticles intravenously into New Zealand White rabbits.
• Compared SPIO-injected rabbits with control groups to identify nanoparticle-specific cellular changes.

Main Results:

• Observed significant cellular intensity enhancements in the spectral range of 2850-2875 cm⁻¹ in hepatic Kupffer cells and spleen melanomacrophages of SPIO-injected animals.
• These spectral enhancements were absent in control animals, indicating SPIO-specific molecular changes.
• The observed enhancements correlate with the selective association of lipid molecules to the uptaken SPIO nanoparticles.

Conclusions:

• SECARS microscopy provides a unique capability to visualize the selective binding of lipids to SPIO nanoparticles in RES cells.
• This finding advances the understanding of nanoparticle-lipid interactions within the cellular environment.
• The developed application holds potential for enhanced diagnostics and targeted therapies involving SPIO nanoparticles.