Vertically aligned carbon nanotube array (VANTA) coatings have recently garnered much attention due in part to their unique material properties including light absorption, chemical inertness, and electrical conductivity. Herein we report the first use of VANTAs grown via chemical vapor deposition in a 2D interdigitated electrode (IDE) footprint with a high height-to-width aspect ratio (3:1 or 75:25 µm). The VANTA-IDE is functionalized with an antibody (Ab) specific to the human cancerous inhibitor PP2A (CIP2A)—a salivary oncoprotein that is associated with a variety of malignancies such as oral, breast, and multiple myeloma cancers. The resultant immunosensor is capable of detecting CIP2A label-free across a wide linear sensing range (1 –100 pg/mL) with a detection limit of 0.24 pg/mL within saliva supernatant—a range that is more sensitive than the corresponding CIP2A enzyme linked immunosorbent assay (ELISA). These results help pave the way for rapid cancer screening tests at the point-of-care (POC) such as for the early-stage diagnosis of oral cancer at a dentist's office.