Nanocrystal targeting in vivo.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Materials Science

Background:

• Inorganic nanostructures are crucial for biological and medical applications.
• Nanoparticles show promise for intravascular diagnostics and therapeutics.
• Effective nanoparticle delivery requires tissue targeting and evasion of the reticuloendothelial system.

Purpose of the Study:

• To investigate the feasibility of in vivo targeting using semiconductor quantum dots (qdots).
• To demonstrate tissue-specific accumulation of peptide-functionalized qdots.
• To assess the role of polyethylene glycol in preventing non-specific accumulation.

Main Methods:

• Synthesis of zinc sulfide-capped cadmium selenide (ZnS-CdSe) quantum dots.
• Functionalization of qdots with lung-targeting, blood vessel-targeting, and lymphatic vessel-targeting peptides.
• Intravenous (i.v.) injection of qdots into mice models.
• Evaluation of qdot distribution in lungs and tumors using fluorescence imaging.
• Assessment of qdot accumulation in reticuloendothelial tissues with and without polyethylene glycol coating.

Main Results:

• ZnS-CdSe qdots coated with a lung-targeting peptide accumulated in mouse lungs post-i.v. injection.
• Other peptides directed qdots to blood vessels and lymphatic vessels within tumors.
• Polyethylene glycol coating on qdots prevented nonselective accumulation in reticuloendothelial tissues.

Conclusions:

• Peptide-functionalized qdots enable targeted delivery to specific tissues in vivo.
• Surface modification with polyethylene glycol enhances nanoparticle circulation and reduces non-specific uptake.
• These findings support the development of advanced nanostructures for disease sensing and drug delivery.