MgZnO Dual Gate Thin Film Transistor for the Sensitive Determination of Modified Folic Acid

Folate receptor (FR) is a typical tumor-associated antigen that has been widely used as a biomarker for the determination of cancer. A biosensing platform functionalized with folic acid (FA) is essential to FR detection because FA specifically binds FR. We demonstrate an MgZnO dual-gate thin-film transistor (MZO DGTFT) based biosensor for the sensitive determination of FA derivative, hexadecyl alkynated folic acid (HAFA). The receptor is an MZO nanostructure (MZO
$_{\mathrm {nano}}$
) modified sensing pad which electrically connects to the top gate of DGTFT. The bottom gate of DGTFT is used to bias the device to its optimum operation point, enabling high sensitivity. First, 11-azidoundecanoic acid (AA) was bond onto the MZO
$_{\mathrm {nano}}$
surface as the linker layer, resulting in negative charges to MZO
$_{\mathrm {nano}}$
due to carboxylic acid binding chemistry. HAFA was then immobilized on MZO
$_{\mathrm {nano}}$
via click reaction with AA. HAFA is a polar molecule with the positive end adjacent to AA/MZO
$_{\mathrm {nano}}$
, and therefore, the electrostatic condition of MZO
$_{\mathrm {nano}}$
is impacted again. Such changes were detected by DGTFT that displayed significant drain current variations. Fourier-transform infrared spectroscopy (FTIR) imaging confirms such successful chemical processes. This MZO DGTFT biosensor with HAFA is promising for potential applications in the detection of FR overexpressed cancer cells.