Via single-harmonic generation, anti-cancer photodynamic therapy can happen deep within the body

May 16, 2014
Photodynamic therapy (PDT) is normally an effective treatment only for easily accessible tumors such as oral and skin cancer; however, researchers at the University at Buffalo (buffalo, NY), have developed a method for activating photodynamic drugs deeper in the body, making many other types of tumors accessible to the therapy.
A laser-irradiated area in tissue (within the white square) shows live cancer cells (green) as well as cancer cells that have been killed (red) as a result of the irradiation. (Image: UB)

Photodynamic therapy (PDT) is normally an effective treatment only for easily accessible tumors such as oral and skin cancer; however, researchers at the University at Buffalo (UB; Buffalo, NY), have developed a method for activating photodynamic drugs deeper in the body, making many other types of tumors accessible to the therapy.1

The technique depends on single-harmonic generation (SHG; also known as frequency-doubling) of IR light by natural body proteins. Near-infrared light (which travels much farther into tissue than visible light) irradiating a relatively deep tumor through the skin is frequency-doubled by collagen, a protein found in connective tissue; the resulting visible or UV light then photodynamically activates cancer-fighting drugs already in the body.1

The SHG happens when the natural proteins and lipids interact with the near-IR light through four-wave mixing and/or coherent anti-Stokes Raman scattering.

"We expect this will vastly expand the applications for an effective cancer phototherapy that's already in use," said co-author Tymish Ohulchanskyy, UB research associate professor and deputy director for photomedicine at the university's Institute for Lasers, Photonics and Biophotonics (ILPB).

"There are no long-term side effects for PDT, it's less invasive than surgery, and we can very precisely target cancer cells," says Paras Prasad, one of the UB researchers.

UB has applied for a patent, and the university's Office of Science, Technology Transfer and Economic Outreach (UB STOR) is discussing potential license agreements with companies interested in commercializing it.

The research is a collaboration between the ILPB, Shenzhen University in China, and Korea University in Korea, with which Prasad is affiliated.

REFERENCE:

1. A. V. Kachynski et al., Nature Photonics (2014); doi:10.1038/nphoton.2014.90

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!