The nanoprobes, developed at the University of Birmingham, inform medics about blood flow and this information helps with the earlier diagnosis of disease. Such disease assessments include thrombosis and vascular inflammation. This information is gleaned from probing the blood capillaries that form the microvasculature.
Thrombosis concerns the formation of a blood clot inside a blood vessel. The presence of the clot obstructs the flow of blood through the circulatory system. Significant health risks can arise when a piece of either an arterial or a venous thrombus break offs (as an embolus) and then travels through the circulation and lodges somewhere else as an embolism.
Vasculitis links together a series of diseases that concern inflammation of the blood vessels. Vasculitis is characterized by inflammation in and damage to the walls of various blood vessels. Symptoms include fatigue and muscle ache.
Current assessments are based on ultrasound technologies. The concern here is with poor resolution and this consequently provides only limited medical data. In addition, conventional methods rely on staining red cells. The staining process is often variable and it the stains only last for a finite time because of a phenomenon called photobleaching. The new alternative nanotechnology has been shown to provide for a more accurate assessment.
Developing the new probes proved to be challenging because of the different, and changing, environmental conditions in the blood (causes by factors like varying red cell content). Overcoming these challenges provided another area where the nanoprobes are superior to standard imaging since high concentrations of red blood cells can interfere with light optical instruments.
Imaging power of nanoprobes
A nanoprobe is a type of optical device. The probe produces an image based on the Raman scattering effect of the light (a type of light reflection). The reflected light demonstrates vibration energies that are unique to each object, allowing them to be characterized and identified.
The new method, devised by Professor Zoe Pikramenou, involves the use of iridium-coated gold nanoparticles. These act as luminescent probes and allow for the optical imaging of blood. Key to the development was the stabilization of the water-soluble gold nanoparticles, for which the use of iridium helped. Iridium is a very hard, brittle, silvery-white transition metal of the platinum group.
The researcher has explained about the process to Controlled Environments magazine: “The key to these iridium-coated nanoparticles lies in both their small size, and in the characteristic luminescent properties.”
Gold particles track blood flow
Professor Pikramenou adds: “The iridium gives a luminescent signal in the visible spectrum, providing an optical window which 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.”
Of particular importance is the size of the nanoprobes which, at a size of 100 nanometers, makes them ideal for not disturbing the blood flow. Trials have shown how the nanoprobes enter blood circulation and are able to become imaged by fluorescence in different organs. As well as imaging, a future application could involve the use of targeted drug delivery within the body.
The research has been published in the journal Nanomedicine. The research paper is titled “Tailoring iridium luminescence and gold nanoparticle size for imaging of microvascular blood flow.”
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we considered a significant advancement has been made with a medical device, in the form of a dialysis membrane, with the ‘super-material’ graphene at its core
The week before we looked at a new tattoo made from bioink that signals health changes relating to the wearer via color changes.