Edwin L. Aguirre
A team of researchers from UMass Lowell, Massachusetts General Hospital and Harvard Medical School is applying nanotechnology to a light-based therapy that could someday help patients fight viruses, bacteria, fungi and cancer cells.
The project, led by Prof. Long Chiang of UMass Lowell’s Chemistry Department and Prof. Mike Hamblin of Wellman Center for Photomedicine at Mass General Hospital, is funded by a four-year, $1.34 million award from the National Institutes of Health.
Called “photodynamic therapy,” or PDT, the technique combines a photosensitizer — a nontoxic, light-sensitive agent functioning as a catalyst — with harmless visible light to produce a photochemical reaction in the presence of oxygen that could wipe out cancer cells and other harmful microorganisms.
In this non-surgical, minimally invasive approach, the photosensitizer is first administered, followed by the irradiation of the tumor or infected tissue with intense light from a powerful lamp or laser. The photosensitizer absorbs the therapeutic light to form free radicals and singlet oxygen. These reactive oxygen species can kill cancer cells and pathogenic bacteria, fungi and viruses directly or by activating the host’s immune system.
Chiang and his team are using chemically modified carbon molecules — called “fullerenes” — as photosensitizer. These nanoparticles, which look like soccer balls measuring only billionths of a meter in size, have 60 carbon atoms arranged in a unique, closed-cage structure.
“Several in vitro studies have shown that cancer cells, such as the human cervical carcinoma, as well as gram-positive and gram-negative bacteria and fungal cells can be killed with fullerene-mediated PDT,” explains Chiang. “Viruses can also be inactivated.”
He says animal tests of PDT with fullerenes have shown that it has the potential to kill numerous classes of microbial cells as well as cancer cells.
“There are reports that PDT with fullerenes can destroy or inhibit subcutaneous tumors growing in mice,” notes Chiang. “One report shows increased survival in a challenging disseminated abdominal cancer model. Another shows it can save the lives of mice with an invasive bacterial wound infection.”
Fullerene cages can also form vesicles (small bubbles) that allow for the improved delivery of anticancer drugs to the affected tissues, he adds.
“In vivo PDT with fullerenes represents a new application in nanomedicine,” says Chiang.