Researchers at Rice University in Houston developed a process using lasers and tiny gas bubbles to kill or modify diseased cells, without affecting neighboring cells. The team from the lab of biochemist Dmitri Lapotko published its findings online in a recent issue of the journal ACS Nano (paid subscription required).
Lapotko, with research scientist and lead author Ekaterina Lukianova-Hleb and undergraduate student Martin Mutonga (pictured right), form vapor bubbles around gold nanoparticles that heat up when activated by an external power source, in this case short laser pulses. The bubbles quickly expand and collapse, vaporizing a thin layer of liquid near the surface of the particle. In earlier research, Lapotko showed gold nanobubbles could isolate and explode diseased cells, such as cancer cells, while leaving nearby healthy cells untouched.
In the new study, the Rice team showed the process can modify selected individual cells, with the same laser pulse that kills diseased cells in the same sample. The researchers placed 60-nanometer-wide (1 nanometer equals 1 billionth of a meter) hollow nanoshells in model cancer cells and stained them red. In a separate batch, they put 60-nanometer-wide solid nanospheres into the same type of cells and stained them blue.
They then suspended the two batches together into a single sample of a green fluorescent dye, and fired a wide laser pulse at the combined sample. The laser creates larger bubbles around the hollow gold nanoparticles than the solid nanoparticles. After washing out the green dye, the results show the larger nanobubbles from the hollow particles explode the red-stained cells.
The laser, however, creates smaller nanobubbles when they interact with the solid particles. These smaller nanobubbles do not destroy the associated cells, but instead puncture the outer walls of the cells, allowing the green dye to be drawn in. The entire process of killing or modifying cells takes a fraction of a second.
Lapotko says as many as 10 billion cells per minute could be selectively processed in a flow-through system like that now under development at Rice, which he says can advance cell and gene therapy, as well as bone marrow transplantation, that today require external processing of human cell grafts or genetic modification to increase therapeutic efficiency. “Current cell processing,” notes Lapotko, “is often slow, expensive, and labor intensive and suffers from high cell losses and poor selectivity.”
The Rice researchers worked on this project with medical colleagues in nearby institutions, notably the Center for Cell and Gene Therapy at Baylor College of Medicine, Texas Children’s Hospital, and the University of Texas MD Anderson Cancer Center.
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