Cancer signals: Enhancing Raman endoscopy

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  • Published: Jul 1, 2011
  • Author: David Bradley
  • Channels: Raman
thumbnail image: Cancer signals: Enhancing Raman endoscopy

Gold label

Radioactively labelled gold nanoparticles can assist in a novel endoscopic technique using Raman spectroscopy to look at microscopic structures, including nascent tumours, deep within the body. Preclinical tests carried out using the technology shows that the gold nanoparticles can be administered safely and used to image the inside of the large intestine. The research bodes well for identification of malignant tissue in the earliest stages of colon cancer.

Way back in 2008, a research team based at Stanford University's Center for Cancer Nanotechnology Excellence showed how nanoparticle-aided Raman spectroscopy might be used to look at microscopic structures, including early tumour growth, deep inside the body. "Raman imaging offers unsurpassed sensitivity and multiplexing capabilities," the researchers explain. However, it has only a limited depth of penetration, which makes it difficult to use in a natural clinical setting. This point was not lost on the team and the researchers reasoned that a more suitable way to exploit Raman's useful characteristics would be to couple the spectroscopic technique with endoscopy, which would open up this approach to diagnostics for colon cancer and perhaps other entry points to the body.

The same team, working with colleagues at the University of Copenhagen, Denmark, has now conducted preclinical tests in extensive studies to show that the gold nanoparticles can be safely administered into the colon and used with a Raman endoscope to image the inside of the large intestine. They report details of their work in the journal Small. Sanjiv Sam Gambhir and colleagues used gold nanoparticles labelled with radioactive copper-64 that allowed them to track the accumulation of the nanoparticle imaging agents inside mice. Micro-positron emission tomography (micro-PET) allowed them to identify the location of the nanoparticles in the body.

Nano tags

The team studied Nanoplex Biotags manufactured by Cabot Security Systems, these SERS nanoparticles are, the team explains, ideal for clinical use as they not only have an inert gold composition but also excellent Raman signal strength, which should allow for ultrasensitive detection characteristics. The particles have up to ten unique spectral fingerprints.

Tests showed that intravenous injection of the nanoparticles led to accumulation in various organs and tissues. Indeed, almost 10 percent of the dose of nanoparticles was destined to accumulate in the liver. By contrast, tumour-targeting nanoparticles introduced rectally into the colon, saw much better targeting with less than 0.1% of the nanoparticles accumulating in tissues outside the large intestine even as long as a fortnight after introduction. The team explains that, in the colon, the nanoparticles could be visualized using an endoscope modified to detect Raman signals. The team says success with this approach offers, "a new way to sensitively detect dysplastic lesions while circumventing Raman?s limited depth of penetration and avoiding systemic toxicity."

The team adds that, "These results suggest that the topical application of SERS nanoparticles in the mouse colon appears to minimize their systemic distribution, thus avoiding potential toxicity and supporting the clinical translation of Raman spectroscopy as an endoscopic imaging tool." The same technology might also be used for endoscopic investigation of the esophagus, cervix and bladder, the team concludes.


The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

Credit: Small/Wiley-VCH Radioactively labelled gold nanoparticles can assist in a novel endoscopic technique using Raman spectroscopy to look at microscopic structures, including nascent tumours, deep within the body. Preclinical tests carried out using the technology shows that the gold nanoparticles can be administered safely and used to image the inside of the large intestine. The research bodes well for identification of malignant tissue in the earliest stages of colon cancer.Intravenous vs intracolonic 

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