U.S. researchers are developing a promising new approach to the targeting of individual cancer cells. The technique uses light-harvesting nanoparticles to convert laser energy into “plasmonic nanobubbles,” enabling drugs to be injected directly into the cancer cells through small holes created in the surface. Researchers claim that the delivery of chemotherapy drugs in this way is up to 30 times more effective on cancer cells than traditional drug treatments and requires less than one-tenth the clinical dose.

The researchers from Rice University, the University of Texas MD Anderson Cancer Center and Baylor College of Medicine (BCM) are in the development stages of the plasmonic nanobubble technique, which aims to more effectively treat individual cancer cells, while at the same time minimizing the harm caused to healthy cells nearby when administering chemotherapy.

“We are delivering cancer drugs or other genetic cargo at the single-cell level,” Rice University principal investigator Dmitri Lapotko says. “By avoiding healthy cells and delivering the drugs directly inside cancer cells, we can simultaneously increase drug efficacy while lowering the dosage.”

The new technique involves forming a nanobubble inside the protective outer wall of an affected cell by striking a plasmon (oscillating electrons on the surface of a metal nanoparticle) with a pulse of laser light. The wavelength of the laser is precisely matched to that of the plasmon, and when it strikes the plasmon it generates heat in order to create a bubble of air and water vapour. The nanobubbles are short-lived events that expand and burst, thus creating a small hole in the surface of a cell and allowing cancer drugs to be injected directly into the cell’s nucleus. By delivering this payload directly inside the cell membrane, the effectiveness of the treatment is greatly improved.

In order to get the nanobubbles inside the target cancer cells, clusters of gold nanoparticles are created within the cells by binding an antibody to individual nanoparticles. These antibodies adhere to the cancer cells before being absorbed to create tiny pockets of nanoparticles just below the cell surface. Then the laser pulse is applied to the plasmon to create a nanobubble.

Using the plasmonic nanobubbles to treat the disease at a single-cell level has been shown to be far more targeted than attaching chemotherapy drugs directly to nanoparticles. Even though a few gold nanoparticles are taken up by healthy cells, the cancer cells take up far more, and require a lower minimum threshold of laser energy to form a nanobubble.

This treatment approach, which is funded by the National Institute of Health, is still in its initial stages, and has yet to be tested on animals. At present, it is the subject of four peer-reviewed studies. However, scientists working in the field on nanomedicine are encouraged by the recent findings, which could bring about a meaningful improvement in the delivery of cancer treatment drugs.

“The nanobubble injection mechanism is an entirely new approach for drug and gene delivery,” said Dr. Malcolm Brenner, professor of medicine and of pediatrics at BCM. “It holds great promise for selectively targeting cancer cells that are mixed with healthy cells in the same culture.”

Dmitri Lapotko discussed the development in the Rice University video below.