Going beyond the surface: New tech couldtake light-based cancer treatment deep insidethe body15 May 2014, by Cory Nealon

The laser irradiated area (the white square) shows livecancer cells (green) as well as dead cancer cells (red)as a result of the irradiation. Credit: University at Buffalo

Photodynamic therapy (PDT) is an effectivetreatment for easily accessible tumors such as oraland skin cancer.

But the procedure, which uses lasers to activatespecial drugs called photosensitizing agents, isn'tadept at fighting cancer deep inside the body.Thankfully, that's changing due to new technologythat could bring PDT into areas of the body whichwere previously inaccessible.

Described May 11 in the journal Nature Photonics,the approach involves using near-infrared beamsof light that, upon penetrating deep into the body,are converted into visible light that activates thedrug and destroys the tumor.

"We expect this will vastly expand the applicationsfor an effective cancer phototherapy that's alreadyin use," said co-author Tymish Ohulchanskyy, PhD,University at Buffalo research associate professorand deputy director for photomedicine at theuniversity's Institute for Lasers, Photonics andBiophotonics (ILPB).

Doctors have used PDT to treat cancer fordecades. Cancer cells absorb the drug, which isdelivered to the tumor via the bloodstream orlocally. Visible light is then applied to the site, whichcauses the drug to react with oxygen and create aburst of free radicals that kill the tumor.

Unfortunately, visible light does not penetrate tissuewell. Conversely, near-infrared light penetratestissue well but doesn't activate the drugs efficiently.

To solve this problem, some researchers aredeveloping drugs that absorb near-infrared light.This method is limited, however, because stableand efficient near-infrared absorbingphotosenzitizers are notoriously difficult tosynthesize.

The UB-led team took a different approach, whichuses the tumor's natural environment to tune thelight into the necessary wavelengths.

For example, the near-infrared laser beam interactswith the natural protein collagen, which is found inconnective tissues. The interaction changes thenear-infrared light to visible light, a process knownas second harmonic generation. Likewise, naturalproteins and lipids within the cells interact with near-infrared laser light and change it to visible lightthrough another process called four-wave mixing.

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Thus, visible light can be generated in tumors deepinside the body, and it can be absorbed by thedrug. This activates the drug, which then destroysthe tumor.

The procedure has numerous advantages, said thestudy's leader, Paras Prasad, PhD, SUNYDistinguished Professor in chemistry, physics,electrical engineering, and medicine at UB, and theILPB's executive director.

"There are no long-term side effects for PDT, it'sless invasive than surgery, and we can veryprecisely target cancer cells," he said. "With ourapproach, PDT is enriched to provide another toolthat doctors can use to alleviate the pain of millionsof people suffering from cancer."

UB has applied for a patent to protect the team'sdiscovery, and the university's Office of Science,Technology Transfer and Economic Outreach (UBSTOR) is discussing potential license agreementswith companies interested in commercializing it.

The research is a collaboration between ILPB,Shenzhen University in China and Korea Universityin Korea, with which Prasad is affiliated. It wassupported in part by a grant from the U.S. Air Forceof Scientific Research. Other co-authors areAliaksandr Kachynski, Artem Pliss, Andrey Kuzminand Alexander Baev, all PhDs and researcherswithin ILPB, and Junle Qu, PhD, ShenzhenUniversity.

More information: Paper: www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2014.90.html

Provided by University at Buffalo

APA citation: Going beyond the surface: New tech could take light-based cancer treatment deep inside thebody (2014, May 15) retrieved 19 May 2015 from http://phys.org/news/2014-05-surface-tech-light-based-cancer-treatment.html

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