Nanoparticle-Laser Method Targets Chemo Drugs

A potential treatment method for drug-resistant cancer uses gold nanoparticles to convert laser energy into “plasmonic nanobubbles,” which allow chemotherapy drugs to enter single cells. Delivering chemotherapy with nanobubbles is 30 times more deadly than traditional drug treatment with less than one-tenth the clinical dose, a study out of Rice University has found.

“We are delivering cancer drugs or other genetic cargo at the single-cell level,” said Dmitri Lapotko, a Rice University biologist and physicist whose plasmonic nanobubble technique is the subject of four new peer-reviewed studies. “By avoiding healthy cells and delivering the drugs directly inside cancer cells, we can simultaneously increase drug efficacy while lowering the dosage.”

Scientists at Rice University have teamed up with the University of Texas MD Anderson Cancer Center and Baylor College of Medicine to develop the nanotechnology. To form the nanobubbles, they injected gold nanoclusters into cancer tells by tagging individual gold nanoparticles with an antibody that binds to the cancer cell’s surface. The cells ingest the gold nanoparticles and sequester them in small pockets just below the surface.

Dmitri Lapotko (Image: Jeff Fitlow/Rice University)

The nanobubbles are tiny pockets of air and water vapor that form when laser light, matched in wavelength to that of the plasmon, strikes a cluster of nanoparticles and is converted instantly into heat. The bubbles expand and burst, briefly opening small holes in the surface of the cells and allowing cancer drugs to rush inside.

By dialing in just the right amount of laser energy, Lapotko’s team can ensure that nanobubbles form only around nanoparticles in cancer cells. A few nanoparticles are taken up by healthy cells, but the cancer cells take up far more; the procedure is selective because the minimum threshold of laser energy needed to form a nanobubble in a cancer cell is too low to form a nanobubble in a healthy cell.

Delivering drugs and therapies that affect only cancer cells and not surrounding healthy cells is an obstacle. Sorting cancer cells from healthy cells has been successfully achieved, but it is both time-consuming and expensive. Researchers also have used nanoparticles to target cancer cells, but because the nanoparticles can be taken up by healthy cells also, attaching drugs to these particles can be tricky.

Using the new technique to pass drugs through a cancer cell’s protective outer wall can dramatically improve the drug’s ability to kill the cancer cell, Lapotko and Xiangwei Wu of MD Anderson showed in two recent studies, one in Biomaterials and the other in Advanced Materials.

“Overcoming drug resistance represents one of the major challenges in cancer treatment,” Wu said. “Targeting plasmonic nanobubbles to cancer cells has the potential to enhance drug delivery and cancer-cell killing.”

This technique could also be used to deliver gene therapies and other therapeutic payloads directly into cells.

The method has not yet been tested in animals and will require more research before it can be ready for human testing, Lapotko said.

Additional research appeared online April 3 in PLoS ONE.

For more information, visit: www.rice.edu