Directly observing intracellular nanoparticle formation with nanocomputed tomography.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Cell Biology

Background:

• Direct visualization of intracellular nanostructure formation is a significant challenge in cell biology.
• Understanding nanoparticle assembly within cells is crucial for developing targeted therapies and diagnostics.

Purpose of the Study:

• To develop a novel small molecule for direct observation of intracellular nanoparticle formation.
• To utilize nanocomputed tomography (nano-CT) for imaging these intracellular nanoparticles.

Main Methods:

• Design and synthesis of a rationally designed small molecule, 4-nitrobenzyl carbamate-Cys(SEt)-Asp-Asp-Phe(iodine)-2-cyano-benzothiazole (NBC-Iod-CBT).
• In vitro investigation of NBC-Iod-CBT self-assembly into nanoparticles (Iod-CBT-NPs) via glutathione reduction and nitroreductase (NTR) cleavage, followed by a CBT-Cys click condensation reaction.
• Application of nanocomputed tomography (nano-CT) to image Iod-CBT-NPs within NTR-overexpressing HeLa cells.

Main Results:

• NBC-Iod-CBT self-assembled into nanoparticles (Iod-CBT-NPs) in vitro with a specific linear absorption coefficient (LAC) for X-ray.
• Nano-CT imaging confirmed the presence of Iod-CBT-NPs within the cytoplasm of treated HeLa cells.
• The observed LAC values for intracellular Iod-CBT-NPs were comparable to in vitro measurements, validating the imaging technique.

Conclusions:

• The developed small molecule and nano-CT imaging strategy enable direct observation of intracellular nanoparticle formation.
• This approach provides a powerful tool for studying the mechanisms of intracellular nanostructure assembly.
• The findings pave the way for deeper insights into cellular processes and potential therapeutic applications.