The so-called “smart” gold nanoshells could lead to more effective cancer treatments that can target cancer cells specifically and leave healthy cells untouched.
According to the researchers at East China Normal University and Tongji University, the peptides on the surface of the nanoshells may improve the targeting ability of drugs and guide the nanoshells to specific cancer cells, as well as attach to markers on the surface of the cells. The acidic environment of the cancer cells then triggers the offloading of the anticancer drugs.
The specific nanostructure of the gold nanoshells could also allow near-infrared light to be absorbed and converted into heat, which could make use of the nanoshells in targeted hyperthermia treatments—another form of cancer treatment whereby cancer cells are exposed to slightly higher temperatures than usual to destroy them.
The first results of the nanoshells' performance were published Friday in IOP Publishing's journal Biomedical Materials.
The researchers used the gold nanoshells as a building block to which they attached the commonly used anticancer drug Doxorubicin and a peptide known as A54.
The gold nanoshells had diameters of around 200 nanometres, which is more than 50 times smaller than a red blood cell. When tested on human liver cancer cells, the uptake of the nanoshells that had the peptide was three times greater than the uptake of the control nanoshells without the peptide. There was also a significantly reduced uptake of both types of nanoshell by normal healthy cells.
The cancer cells were also treated with the gold nanoshells in a heated water bath and were shown to deliver a notable therapeutic effect compared to just the chemotherapy.
Lead author of the study Dr Shunying Liu, from East China Normal University, did not respond to a request for comment. But he said in a statement: "The therapeutic activity of most anticancer drugs is limited by their systematic toxicity to proliferating cells, including some normal cells. Overcoming this problem remains a great challenge for chemotherapy."
"In our study we placed a targeting peptide on the nanoshells, which have been demonstrated to be specific to live cancer cells, improving the targeting ability and drug delivery of the gold nanoshells.”
Flow cytometry and fluoroscopy analysis were conducted to reveal the enhanced cell apoptosis caused by the A54-modified gold nanoshells under combined chemotherapeutic and hyperthermia therapies.
“These results imply that DOX/A54@GNs [gold nanoshells] could be used as a multifunctional nanomaterial system with pH-triggered drug-releasing properties for tumor-targeted chemotherapy and hyperthermia,” the authors wrote.
"The next step of our research is to test the 'smart' gold nanoshells in vivo on a liver cancer mouse model. We will also examine how the size of the nanoshells changes their efficacy and how efficient the nanoshells are at converting near-infrared light into heat," the authors added.