Electrical detection of kinase assay using multi walled-carbon nanotube(MWCNT) nanoelectrode

We have demonstrated the use of MWCNT as a nanoscale probe to monitor the activity of enzyme kinase. To immobilize the substrate peptide using carbodiimide chemistry, plasma or strong acid treatments were used to induce carboxyl groups on the sidewall of MWCNTs. After the susbtrate peptide immobilization, increase of conductance from MWCNT devices was observed. When peptide modified MWCNTs react with enzyme kinase, conductance decreases by several orders of magnitude, and this conductance change can be explained by the phosphorylation reaction of enzyme kinase. When the sample was incubated with phosphatase to dephosphorylate the substrate peptide, nearly complete recovery of the conductance signal has been observed and we can confirm that we have monitored the kinase activity.