Nanodaisies can carrier a drug combination with more precision for improved cancer treatment

NC State researchers have developed a potential new weapon in the fight against cancer: a daisy-shaped drug carrier that’s many thousands of times smaller than the period at the end of this sentence.

Once injected into the bloodstream, millions of these “nanodaisies” sneak inside cancer cells and release a cocktail of drugs to destroy them from within. The approach is more precise than conventional methods, and it may also prove more effective. By ensuring anti-cancer drugs reach their target in controlled, coordinated doses, nanodaisies could cut down on the side effects of traditional chemotherapy.

“By using one nanocarrier to contain two different drugs, we can potentially reduce their dose and toxicity,” said Dr. Zhen Gu, assistant professor in the Joint Department of Biomedical Engineering at NC State and UNC-Chapel Hill. “And meanwhile their anti-cancer efficacy is enhanced.”

The nanocarriers are made from a polymer called polyethylene glycol (PEG), to which researchers attach the cancer-killing drug camptothecin (CPT) like bunches of grapes on a vine. A second drug, doxorubicin, also floats in solution around the PEG.

Both drugs are hydrophobic, meaning they dislike water and shy away from it. PEG, though, is hydrophilic: When exposed to water it stretches out to maximize contact, while the T-shaped joints that hold the CPT tug in the opposite direction and fold inward. The anti-cancer drugs thus end up tucked into a protective shell of PEG. The resulting nanocarrier is shaped like a flower — hence the term “nanodaisy.”

“The idea came from thinking actively about folding proteins in nature,” noted Gu, referring to the way amino acids can assemble themselves into thousands of different shapes. “It’s a sort of bio-inspired design.”

Once folded, the nanodaisies are then injected into the bloodstream and absorbed by unwitting cancer cells, which are porous enough to let them in. The nanodaisies’ outer shells of PEG protect their payload of drugs and keep them from prematurely leaking.

The design of the nanodaisy also ensures that the two cancer drugs release at complementary speeds as their carrier comes apart inside the cancer cell. Each drug inhibits different enzymes in the cell, and they work in tandem to prevent or delay the development of drug resistance.

The result is that the drugs launch an attack on cancer that’s more closely coordinated and tightly targeted than traditional drug cocktails.