A novel application for detecting specific biomolecules using SWNT-ssDNA nanohybrid is described. SWNT-ssDNA hybrid is formed by conjugating amino-ended single strand of DNA (ssDNA) with carboxylic group modified SWNTs through a straightforward EDC coupling reaction. ssDNA functionalized SWNT hybrids could be used as high fidelity sensors for biomolecules. The sensing capability is demonstrated by the change in the electronic properties of SWNT. Employing DNA functionalized SWNT FETs could lead to dramatically increased sensitivity in biochemical sensing and medical diagnostics applications.