To acquire images, chemists from Trinity College Dublin attach luminescent compounds to gold structures to form biologically safe 'nanoagents' that are attracted to calcium-rich surfaces, which appear when bones crack. These nanoagents target and highlight the cracks formed in bones, allowing researchers to produce a complete 3D image of the damaged regions.
The technique can be used to diagnose bone strength and provide a detailed outline of the extent and precise positioning of any weakness or injury, or act as an early-warning system for people at a high risk of degenerative bone diseases.
The research, led by the Trinity College Dublin team of Professor of Chemistry, Thorri Gunnlaugsson, and Postdoctoral Researcher, Esther Surender, is described in Chem.
Prof Gunnlaugsson said: " This is a major step forward in our endeavour to develop targeted contrast agents for bone diagnostics for use in clinical applications."
The work was funded by Science Foundation Ireland and by the Irish Research Council, and involved collaboration with scientists at RCSI (Royal College of Surgeons in Ireland), led by Professor of Anatomy, Clive Lee.
Prof Lee said: "Everyday activity loads our bones and causes microcracks to develop. These are normally repaired by a remodelling process, but, when microcracks develop faster, they can exceed the repair rate and so accumulate and weaken our bones.
“Current X ray techniques can tell us about the quantity of bone present but they do not give much information about bone quality. By using our new nanoagent to label microcracks and detecting them with magnetic resonance imaging (MRI), we hope to measure both bone quantity and quality and identify those at greatest risk of fracture and institute appropriate therapy. Diagnosing weak bones before they break should therefore reduce the need for operations and implants - prevention is better than cure."
In addition to the resolution achieved by this imaging technique, another major step forward lies in it not exposing X-rays to patients. The red emitting gold-based nanoagents used in this alternative technique are biologically safe.
Dr Surender said: "These nanoagents have great potential for clinical application. Firstly, by using gold nanoparticles, we were able to lower the overall concentration of the agent that would have to be administered within the body, which is ideal from a clinical perspective. Secondly, by using what is called 'two-photon excitation' we were able to image bone structure using long wavelength excitation, which is not harmful or damaging to biological tissues."
"These nanoagents are similar to the contrast agents that are currently being utilised for MRI within the clinic, and hence have the potential to provide a novel means of medical bone diagnosis in the future. Specifically, by replacing the Europium with its sister ion Gadolinium, we can tune into the MRI activity of these nanoagents for future use alongside X-ray and computed tomography (CT) scans."
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