Balaji Panchapakesan,assistant professor of electrical and computer engineering at UD, hasrecently reported on the discoveries in the journals NanoBiotechnologyand Oncology Issues.
He is the lead investigator for a team thatincludes Eric Wickstrom, professor of biochemistry and molecularbiology at Thomas Jefferson University in Philadelphia and his studentGreg Cesarone, and UD graduate students Shaoxin Lu, Kousik Sivakumarand postdoctoral researcher Kasif Teker.
Panchapakesan said thisis basic research in the very early stages of inquiry and that it wouldtake extensive testing and years of clinical trials before thenanobombs could actually be used in medical applications to treat humanbeings.
“Make no mistake, we are focused on eradicating cancer,”Panchapakesan said, explaining that the nanobombs are the result ofwork over the past two years with carbon nanotubes, which are atoms ofcarbon arranged in tubular form.
Originally, he said, theresearch team was looking at the use of the carbon nanotubes as drugdelivery vehicles. Because they are smaller than the size of a singlecell, the nanotubes can provide for the highly selective injection ofdrugs into individual cells.
As they undertook variousexperiments, however, the team made a startling discovery. “When youput the atoms in different shapes and forms, they take on differentproperties at the nanoscale,” Panchapakesan said. “We wereexperimenting with the molecules and considering optical and thermalproperties, and found we could trigger microscopic explosions ofnanotubes in wide variety of conditions.”
Explosions in air ofloosely packed nanotubes have been seen before in an oxygenenvironment, creating ignition. However, the work reported byPanchapakesan uses the localized thermal energy imbalance to set offexplosions that are intrinsic in nature.
Panchapakesan said thenanobombs are just that, tiny bombs on the nanoscale. “They work almostlike cluster bombs,” he said. “Once they are exposed to light and theresulting heat, they start exploding one after another.”
Thebombs are created by bundling the carbon nanotubes. With a singlenanotube, the heat generated by the light is dissipated by surroundingair. In bundles, the heat cannot dissipate as quickly and the result is“an explosion on the nanoscale,” Panchapakesan said.
When the UDresearchers saw the explosions, they realized it might be possible touse the microscopic bombs to kill cancer cells. They recreated theexplosions in solutions including water, phosphate and salt, whichmeant the nanobombs could be used in the human body. In fact theexplosions were more dramatic in saline solutions, Panchapakesan said.
“Thenanobomb is very selective, very localized and minimally invasive,”Panchapakesan said. “It might cause what I would call nanopain, like apin prick.”
He believes the nanobomb holds great promise as atherapeutic agent for killing cancer cells, with particular emphasis onbreast cancer cells, because its shockwave kills the cancerous cells aswell as the biological pathways that carry instructions to generateadditional cancerous cells and the small veins that nourish thediseased cells. Also, it can be spread over a wide area to createstructural damage to the cancer cells that are close by.
Thenanobombs are superior to a variety of current treatments because theyare powerful, selective, non-invasive, nontoxic and can incorporatecurrent technology, including microsurgery.
An advantage overother carbon nanotube treatments being considered by scientists is thatwith nanobombs, the carbon nanotubes are destroyed along with thecancer cells. Once the nanobombs are exploded and kill cancer cells,macrophages can effectively clear the cell debris and the explodednanotube along with it.
Other treatments retain the carbonnanotubes and nanoparticles intact. If the material finds its way tothe kidney or accumulates in the blood vessels, the nanoparticles mightcause blockage and create problems, Panchapakesan said. Furthermore,the nanobomb route is probably the only way to use nanotubes withoutany cytotoxicity as the nanotubes are destroyed completely.
Currentsurgical techniques are not precise and cancerous cells are often leftbehind. In addition, cancers in some part of the body, such as arteriesand veins, are sometimes considered inoperable. Nanobombs can be usedto target any remaining cancerous cells and can be used in any part ofthe body, allowing the creation of nanobomb therapy for a wide varietyof cancers.
Panchapakesan said the method is far better thanmodern chemotherapy, which is non-selective, kills normal cells as wellas cancerous cells and leads to a decline in the quality of life forthe patient. “This is valuable in patient management, pain managementand overall quality of life,” he said.
Furthermore, Panchapakesansaid, the nanobomb is a “very simple technique” and as such will likelyprove to be “more robust and with the best chance to succeed.”
Panchapakesanadded, “We are just getting started in this area. There is plenty ofwork ahead to successfully translate this into clinical medicine.”
Inaddition to treatment, he believes nanotechnology can provide new toolsfor cancer diagnosis through the use of tiny nanosensors.
“In thefuture, my vision is that people will have at-home kits that can detectcancer. After work they will be able to go to a clinic, be treated withnanobombs and go home,” Panchapakesan said. While these initialexperiments are on breast cancer cells, he is also working to extendhis method to prostate cancer and pancreatic cancer.
He alsoforesees nano-bio-robots or nano-surgical tools that can be placedinside the body to remove tumors in areas previously inaccessible usingtraditional treatment methods.
Panchapakesan said the team’sfindings are the result of interdisciplinary research. “Differentsciences come together to make this work,” he said, citing cancerbiology, physics, electrical and computer engineering and chemistry.“Interdisciplinary research provides for fresh perspectives and bringsabout new ideas, which is probably the way to go in the future.”
Funding for the research was provided in part by the Department of Defense’s Congressionally Directed Medical Research Program.
Panchapakesanreceived his bachelor’s degree in materials engineering at RegionalEngineering College in India and doctorate in mechanical engineeringfrom the University of Maryland at College Park in 2001 before joiningthe faculty at UD. His work is in the area of micro- andnano-electromechanical systems (MEMS),
nanotechnology and biomedical research.
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