Tissue penetration depth is a major challenge in practical
photodynamic therapy. Traditionally, it involves the patient receiving a
nontoxic light-sensitive drug, which is absorbed by all the body's
cells, including cancerous ones.
A red laser light specifically tuned to
the drug molecules is then selectively turned on in the tumor area.
When the red light interacts with the photosensitive drug, it produces a
highly reactive form of oxygen (singlet oxygen) that kills the
malignant cancer cells while leaving most neighboring cells unharmed.
‘A new class of molecules used in photodynamic therapy that are able to direct lamp light deep into tissue to kill cancer tumors has been designed by scientists.’
Based on a research by the UMass Medical School scientist Gang Han and his colleagues, the process might become simpler, more effective and cost efficient. The team has
designed a new class of molecules used in photodynamic therapy that are
able to direct lamp light deep into tissue to kill cancer tumors.
In a new paper published in the Journal of the American Chemical Society
Dr. Han, associate professor of biochemistry & molecular
pharmacology, outlines how the carbazole-substituted BODIPY (Car-BDP)
molecules, which possess an intense, broad NIR absorption band with a
remarkably high singlet oxygen quantum yield, will further the potential
clinical application for photodynamic therapy.
"This study signals a major step forward in photodynamic therapy by
developing a new class of NIR-absorbing biodegradable organic
nanoparticles for a highly effective targeting and treatment of
deep-tissue tumors," Han said.
Han explained that after being encapsulated with biodegradable
polymers, Car-BDP molecules can form uniform and small, organic
nanoparticles that are water-soluble and tumor targetable. Used in
conjunction with a record low-power-density and cost-effective
incoherent lamp light, rather than the coherent high power laser light
that is used in the existing therapy, the molecules can be tracked as
they spread through the body, deep into the tissue and to outline and
kill cancerous tumors. More interestingly, the organic nanoparticles
were found to have an extremely long circulating time and can be removed
from body, which is essential for new practical photodynamic therapy
drug development, Han said.
Han said the combination is "sufficient to monitor and trigger
practical photodynamic therapy effect of these nanoparticles within a
wide variety of deep-tissue level tumors such as lung, colon, prostate
and breast cancers."
In addition, the potential new platform for precise tumor-targeting
theranostics and novel opportunities with low power lamp light could
allow for future affordable clinical cancer treatment that patients may
be able to manage in their homes or resource deficient areas, such as on
battlefields and in developing countries.