New biosensor made of nanotubes

Standard sensors employ metal electrodes coated with enzymes that react with compounds and produce an electrical signal that can be measured. However,the inefficiency of those sensors leads to imperfect measurements. Now, scientists at Purdue University have developed a new method for stacking synthetic DNA and carbon nanotubes onto a biosensor electrode.

Carbon nanotubes, cylindrically shaped carbon molecules known to have excellent thermal and electrical properties, have been seen as a possibility for improving sensor performance. The problem is that the materials are not fully compatible with water, which limits their application in biological fluids.

Marshall Porterfield and Jong Hyun Choi have found a solution and reported their findings in the journal The Analyst, describing a sensor that essentially builds itself.

"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."

Choi developed a synthetic DNA that will attach to the surface of the carbon nanotubes and make them more water-soluble. "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.