CIP2A immunosensor comprised of vertically-aligned carbon nanotube interdigitated electrodes towards point-of-care oral cancer screening

Abstract

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 heightto-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. Table of Content (ToC) Image Description: (Left) Schematic diagram showing antibody functionalized (anti-CIP2A) vertically aligned carbon nanotubes (VANTAs) arrayed in an interdigitated electrode (IDE) footprint. (Left Inset) An optical image of a VANTA IDE immunosensor fabricated on silicon wafer. (Right) Electrochemical impedance sensing of CIP2A antigen concentrations with the biofunctionalized VANTA IDEs.

Nanoparticles for Oral Cancer Diagnosis and Therapy

“…e sensor demonstrated the ability to detect cancerous inhibitor PP2A (CIP2A) in saliva supernatant without the requirement for sample preconcentration or prelabeling techniques, showing higher biosensor sensitivity than the ELISA test kit. Moreover, this biosensor can save the total sensing time [129].…”

Electrochemical Glucose Sensors Enhanced by Methyl Viologen and Vertically Aligned Carbon Nanotube Channels

“…The nominal void ratio of each electrode was 0.41. VACNTs coated with amorphous carbon have been shown to have a high number of surface defects that are favorable for increasing charge transfer, as previously shown by Raman spectroscopy 43. For the enzymatic sensors, the mass of the deposited Pt was measured to be 4.46 ± 0.70 mg (14.7 ± 2.3 % of sensor by weight).…”

3D Interdigitated Vertically Aligned Carbon Nanotube Electrodes for Electrochemical Impedimetric Biosensing

“…[22][23][24] Although such tall heights are not typically reported for electrochemical biosensors, our previous work with an oral cancer biomarker had a VACNT electrode height of about 75 µm and gap of 25 µm. 13 Smaller gap width between tall VACNT electrodes may likely improve sensitivity, a relationship that has previously been shown with planar electrodes. 25 Previous IDE sensors were made entirely of VACNTs, including the interdigitated fingers and the electrical leads.…”

“…It has previously been shown by Raman spectroscopy that VACNTs coated with amorphous carbon have a high number of surface defects, an attribute favorable for increasing the number of sites where proteins can bind and increasing charge transfer during electrochemical measurements. 13 Due to the addition of amorphous carbon to the VACNTs, defect sites that host carboxyl groups are present throughout the VACNT electrode surface. These carboxyl groups were activated by EDC/NHS chemistry to allow fluorescently tagged streptavidin (F-SA) to covalently bond to the VACNTs (see Scheme 1).…”

“…The high surface-area-to-volume ratio that comes from the 3D, porous VACNT electrodes enables higher protein capture capacity relative to planar electrodes, leading to the potential for improved sensitivity. [12][13] High sensor sensitivity is important for enabling detection of low concentrations of target analyte, opening the door for new sensing applications, such as early diagnostics.…”