Nano cancer scanner

The key to their novel imaging agent is a tumour-specific protease, which is found, as the name would suggest, primarily in and around tumour cells. Bhatia and her team engineered a method by which iron(III) oxide, Fe3O4, nanoparticles could form aggregate clusters under physiological conditions. To begin, the team coated one half of a batch of nanoparticles with the protein biotin and the other half with its counterpart neutravidin. Biotin and neutravidin have a strong affinity for each other and bond spontaneously, so would, left to their own devices, allow the nanoparticles to form aggregates randomly .However, non-specifically aggregating nanoparticles have no tumour-targeting capabilities. To make assembly specific to the presence of tumors, Bhatia and her colleagues precluded the assembly by using a peptide-attached PEG protecting group. Removal of the PEG peptide inhibitors can only occur under the enzymic direction of the tumour-associated enzyme, matrix metalloproteinase-2 (MMP-2). Thus, the protein-modified nanoparticles can float freely and dispersed until they reach either tumour or metastatic cells in the body. At this point MMP-2 cleaves the protecting peptide group, exposing the biotin and neutravidin proteins on the surface of the nanoparticles, allowing them to bond. As nanoparticles form aggregates they become clearly visible using MRI, potentially allowing a radiologist to obtain a clear picture of a tumour and detect any metastases elsewhere in the body. The researchers haven't yet demonstrated that this works in animals and while the protease is associated with and present at higher concentrations within tumours, it is not completely specific to them, team member Geoff von Maltzahn told us. As such, the team is now beginning animal studies to evaluate the sensitivity of this method for detecting tumour invasion and hopes to expand this method for delivering drugs to tumours as well. "Source":[ http://www.spectroscopynow.com/coi/cda/detail.cda?id=13563&type=Feature&chId=3&page=1]

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