Microneedles Capable of Connecting the (Quantum) Dots Could Aid Skin Cancer Treatment

Researchers from North Carolina State University (Raleigh) have developed extremely small microneedles that can be used to deliver medically relevant nanoscale dyes to the skin. Known as quantum dots, these dyes are composed of nanoscale crystals featuring unique light-emission properties. This advance, according to the scientists, could open the door to new techniques for diagnosing and treating a variety of medical conditions, including skin cancer. A paper describing the study, "Multiphoton Microscopy of Transdermal Quantum Dot Delivery Using Two Photon Polymerization-Fabricated Polymer Microneedles," will be published in Faraday Discussions.

Microneedles are very small needles in which at least one dimension, such as length, is less than one millimeter. In these tests, the microneedles were created using two-photon polymerization, an approach pioneered by NC State and Laser Zentrum Hannover (Germany) for use in medical device applications. Two-photon polymerization allowed the NC researchers to create hollow, plastic microneedles with specific design characteristics. "Our use of this fabrication technology highlights its potential for other small-scale medical device applications," explains Roger Narayan, a lead reseracher on this project and a professor in the joint biomedical engineering department of NC State's College of Engineering and the University of North Carolina (Chapel Hill).

After creating the plastic microneedles, the researchers tested them using pig skin, which has characteristics closely resembling those of human skin. Using a water-based solution containing quantum dots, the researchers were able to capture images of the quantum dots entering the skin using multiphoton microscopy. These images show the mechanism by which the quantum dots enter the layers of skin, allowing the researchers to verify the effectiveness of the microneedles as a delivery mechanism for these nanoscale dyes.

"We were able to fabricate hollow, plastic microneedles using a laser-based rapid prototyping approach and found that we could deliver a solution containing quantum dots using these microneedles," Narayan says. "The motivation for the study was to see whether we could use microneedles to deliver quantum dots into the skin. Our findings are significant, in part, because this technology will potentially enable researchers to deliver quantum dots, suspended in solution, to deeper layers of skin. That could be useful for the diagnosis and treatment of skin cancers, among other conditions."

The study is also significant because it shows that a laser-based rapid prototyping approach allows for the creation of microneedles of varying lengths and shapes. This will allow medical device manufacturers to create microneedles that are customized for treatment of specific conditions.

For more information on Narayan's work with microneedles, see the Medtech Pulse blog "Microneedles Incorporating Antimicrobial Agents Could Be the Wave of the Future."