Researchers at the Lawrence Berkeley National Laboratory, or Berkeley Lab, Molecular Foundry have created a type of polymer that may help fight diseases via photothermal therapy.
Photothermal therapy is a therapeutic treatment in which chemical reagents that absorb light to create heat can be used to cause hyperthermia and kill bacteria, viruses and cells in localized areas, according to the study’s lead researcher Yi Liu. The type of polymer could prove to be helpful in treating diseases such as cancer.
Most chemical agents used in photothermal therapy are harmful to humans, according to a Jan. 30 Berkeley Lab press release.
“Organic photothermal reagents are less toxic and potentially more efficient compared to inorganic (photothermal therapy) reagents based on metal- or carbon nanostructures,” Liu said in an email. “However the available classes of such reagents are pretty limited.”
The polymer created by Berkeley Lab is significant because it is the first conjugated polyelectrolyte, or CPE, a type of organic photothermal reagent and polymer, that can absorb the range of light optimal for photothermal therapy, according to the Berkeley Lab press release.
CPEs are a type of polyelectrolyte, which is a category of organic polymers whose subunits contain ionic groups, according to a Berkeley Lab Molecular Foundry press release. When these subunits are fully connected by alternating single and double bonds, they become CPEs.
Liu said photothermal therapy uses near-infrared light because it is less harmful to normal cells and tissue than other types of light. CPEs rarely absorb light in ranges optimal for photothermal therapy, according to the Berkeley Lab press release.
“We weren’t originally planning to create a material useful for photothermal therapy, but found that the ionic polymer we made also strongly absorbs near-infrared light,” Liu said in the Berkeley Lab Molecular Foundry press release.
The polymer was developed while the team was constructing CPEs for organic electrochemical transistors and was created by connecting small molecules known as ionic azaquinodimethanes, or iAQMs, according to the Berkeley Lab Molecular Foundry press release.
The research team tested the polymer on Staphylococcus aureus cultures, which is relevant to antibiotic-resistant bacterial infections, according to the Berkeley Lab Molecular Foundry press release. It was found that photothermal therapy using the polymer led to a 95% reduction in bacterial colony count for these cultures.
Liu said that the next steps for the polymer include working on its biocompatibility so that the polymer can be more easily internalized by cells.
Additionally, the polymer and its successful use in photothermal therapy act as a starting point for the creation of more synthetic polymeric photothermal therapy reagents, according to Liu.
“Given the versatile chemical tunability, they can be also coupled with directing groups for targeted treatment of cancer cells,” Liu said in the email.