Purdue University scientists have developed a method for combining synthetic DNA and carbon nanotubes onto a biosensor electrode that may lead to more accurate measurements of glucose, ATP, and other compounds related to diabetes and other diseases.

Standard sensors employ metal electrodes coated with enzymes that react with compounds and produce an electrical signal that can be measured. But the inefficiency of those sensors leads to imperfect measurements.

Carbon nanotubes have been seen as a possibility for improving sensor performance, but have not been fully compatible with water, which limits their application in biological fluids.

Marshall Porterfield, a professor of agricultural and biological engineering and biomedical engineering, and Jong Hyun Choi, an assistant professor of mechanical engineering, have found a solution: a self-assembling synthetic DNA that attaches to the surface of the carbon nanotubes and make them more water-soluble.

“In the future, we will be able to create a DNA sequence that is complementary to the carbon nanotubes and is compatible with specific biosensor enzymes for the many different compounds we want to measure,” Porterfield said. “It will be a self-assembling platform for biosensors at the biomolecular level.

“Once the carbon nanotubes are in a solution, you only have to place the electrode into the solution and charge it. The carbon nanotubes will then coat the surface,” Choi said. The electrode coated with carbon nanotubes will attract the enzymes to finish the sensor’s assembly.

The sensor described in the findings was designed for glucose. But Porterfield said it could be easily adapted for various compounds.

“You could mass produce these sensors for diabetes, for example, for insulin management for diabetic patients,” Porterfield said. He said using this technology, it may one day be possible to develop other sensors that could lead to more personalized medicines. These could test the effectiveness of drugs on their targets in real time.

Jin Shi, et al., Microbiosensors based on DNA modified single-walled carbon nanotube and Pt black nanocomposites, Analyst, 2011; 136 (23): 4916 [DOI: 10.1039/] (free access with registration)