Gold nanoparticles track blood flow. (Credit: University of Birmingham)

Scientists have designed gold nanoparticles, no bigger than 100 nm, that can be coated and used to track blood flow in the smallest blood vessels in the body. By improving our understanding of blood flow in vivo, the nanoprobes represent an opportunity to help in the early diagnosis of disease.

The ability to monitor blood flow in the sophisticated vascular tree (notably in the smallest elements of the microvasculature — capillaries) can provide invaluable information to understand disease processes such as thrombosis and vascular inflammation. There are further applications for the improved delivery of therapeutics, such as targeting tumors.

The researchers have developed a method for the preparation of iridium-coated gold nanoparticles as luminescent probes for optical imaging in blood. The iridium gives a luminescent signal in the visible spectrum, providing an optical window that can be detected in blood. It is also long-lived compared to organic fluorophores, while the tiny gold particles are shown to be ideal for tracking flow and be detected clearly in tissues.”

The team was able to stabilize water-soluble gold nanoparticles, coated with the iridium luminescent probes — at up to 100 nm in size using a surfactant coating. The size is ideal for not disturbing the flow, yet still being detectable by high resolution imaging using conventional microscopes.