Nanocrystal targeting <i>in vivo</i>

TLDR

Inorganic nanostructures, such as semiconductor quantum dots, are increasingly studied for biomedical imaging and drug delivery, but effective targeting of specific tissues while evading the reticuloendothelial system remains a key challenge. The study investigates the feasibility of in vivo targeting using semiconductor quantum dots. ZnS‑capped CdSe quantum dots functionalized with a lung‑targeting peptide accumulated in mouse lungs after intravenous injection, while alternative peptides directed the particles to tumor blood vessels or lymphatics, and polyethylene glycol coating prevented nonspecific reticuloendothelial uptake, supporting the design of multifunctional nanostructures for disease sensing and drug delivery.

Abstract

Inorganic nanostructures that interface with biological systems have recently attracted widespread interest in biology and medicine. Nanoparticles are thought to have potential as novel intravascular probes for both diagnostic (e.g., imaging) and therapeutic purposes (e.g., drug delivery). Critical issues for successful nanoparticle delivery include the ability to target specific tissues and cell types and escape from the biological particulate filter known as the reticuloendothelial system. We set out to explore the feasibility of in vivo targeting by using semiconductor quantum dots (qdots). Qdots are small (&lt;10 nm) inorganic nanocrystals that possess unique luminescent properties; their fluorescence emission is stable and tuned by varying the particle size or composition. We show that ZnS-capped CdSe qdots coated with a lung-targeting peptide accumulate in the lungs of mice after i.v. injection, whereas two other peptides specifically direct qdots to blood vessels or lymphatic vessels in tumors. We also show that adding polyethylene glycol to the qdot coating prevents nonselective accumulation of qdots in reticuloendothelial tissues. These results encourage the construction of more complex nanostructures with capabilities such as disease sensing and drug delivery.