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Posted: June 13, 2008
Quantum rods probe blood-brain barrier
(Nanowerk News) One of the chief difficulties in treating brain tumors involves getting potential tumor-killing drugs across the blood-brain barrier and into the brain. Now, researchers from a NCI Cancer Nanotechnology Platform Partnership at the University of Buffalo have used targeted quantum rods both to breach the blood-brain barrier and to study how such constructs move across this largely impermeable barrier. Paras Prasad, Ph.D., principal investigator of the SUNY-Buffalo Platform Partnership, led the research team that published results in the journal Bioconjugate Chemistry ("Bioconjugated Quantum Rods as Targeted Probes for Efficient Transmigration Across an in Vitro Blood-Brain Barrier").
The investigators began their work by preparing red- and orange-emitting quantum rods made of cadmium selenide, cadmium sulfide, and zinc sulfide. They then attached an iron-transporting protein known as transferrin to the surface of the quantum rods. Transferrin binds to a complex protein known as the transferrin receptor. The blood-brain barrier contains large numbers of this receptor, and research has shown that it can act to transport biomolecules across the blood-brain barrier.
Because of the intense fluorescence exhibited by quantum rods, the investigators were able to image these markers as they bound to and moved across a cell-based model of the blood-brain barrier. In contrast, quantum rods lacking surface transferrin did not cross the model blood-brain barrier. One interesting finding from these experiments is that there appears to be a critical period that starts after 26 hours at which time transport is most efficient across the blood-brain barrier. The investigators note that the data from these experiments should help them design new nanoscale agents for ferrying anticancer drugs into the brain.