Researchers create smaller, brighter probe tailored for molecular imaging and tumor...(will serve as an initial step towards im...),Health

Many of the contrast agents or probes currently used in medical imaging (such as GdDTPA for magnetic resonance imaging) are not specific to any particular tumor type. According to the study's authors, the information gained from imaging tumors targeted with C dots may ultimately assist physicians in defining tumor borders for surgery, determining the extent of a tumor's spread, mapping lymph node disease, and improving real-time visualization of small vascular beds, anatomic channels, and neural structures during surgery.

Created at Cornell University and modified at MSKCC, C dots have been optimized for use in optical and PET imaging and can be tailored to any particle size without adversely impacting its fluorescent properties. For the first time, researchers were able to make them small enough (in the 5 nanometer range) to remain in the bloodstream for a reasonable amount of time and be efficiently excreted by the kidneys. Researchers were also able to increase their brightness by 300 percent, enabling cancer cells to be tracked for longer periods of time in the body.

Their inner "core" is encapsulated in a shell of silica, a nontoxic element naturally found in fruits, grains, and vegetables, and contains optical dyes that emit light at longer wavelengths, resulting in an overall improvement in image quality compared to dyes that are commercially available.

Investigators also found that adding another type of molecular coating, called pegylation, protected C dots from being recognized by the body as foreign substances, thereby effectively extending the circulation time to improve tumor-targeting capabilities.

By comparison, first generation nanoparticles, called quantum dots (Q dots), offer excellent brightness and provide good contrast during imaging, but their clinical potential is limited by their
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