Ultrasensitive and Highly Selective Graphene-Based Field-Effect Transistor Biosensor for Anti-Diuretic Hormone Detection

Abstract

Nephrogenic diabetes insipidus (NDI), which can be congenital or acquired, results from the failure of the kidney to respond to the anti-diuretic hormone (ADH). This will lead to excessive water loss from the body in the form of urine. The kidney, therefore, has a crucial role in maintaining water balance and it is vital to restore this function in an artificial kidney. Herein, an ultrasensitive and highly selective aptameric graphene-based field-effect transistor (GFET) sensor for ADH detection was developed by directly immobilizing ADH-specific aptamer on a surface-modified suspended graphene channel. This direct immobilization of aptamer on the graphene surface is an attempt to mimic the functionality of collecting tube V 2 receptors in the ADH biosensor. This aptamer was then used as a probe to capture ADH peptide at the sensing area which leads to changes in the concentration of charge carriers in the graphene channel. The biosensor shows a significant increment in the relative change of current ratio from 5.76 to 22.60 with the increase of ADH concentration ranging from 10 ag/mL to 1 pg/mL. The ADH biosensor thus exhibits a sensitivity of 50.00 µA· ( g / mL ) - 1 with a limit of detection as low as 3.55 ag/mL. In specificity analysis, the ADH biosensor demonstrated a higher current value which is 338.64 µA for ADH-spiked in phosphate-buffered saline (PBS) and 557.89 µA for ADH-spiked in human serum in comparison with other biomolecules tested. This experimental evidence shows that the ADH biosensor is ultrasensitive and highly selective towards ADH in PBS buffer and ADH-spiked in human serum.

Keywords: ADH-specific aptamer; anti-diuretic hormone; artificial kidney; drain current; graphene FET.

Figure 1

Role of anti-diuretic hormone (ADH) in maintaining plasma osmolality of human body.

Figure 2

(a) Optical microscope image of graphene-based field-effect transistor (GFET) with 10 µm channel length; (b) energy-dispersive X-ray analysis (EDX) spectrum for GFET device; (c) atomic force microscopy (AFM) image for bare GFET and (d) AFM image of GFET after ADH detection.

Figure 3

(a) Graphene on copper; (b) graphene on field-effect transistor (FET); (c) Raman spectrum for graphene on copper; (d) Raman spectrum for graphene on electrodes and (e) Raman spectrum (average value) for graphene on copper and FET.

Figure 4

Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra for surface functionalization of graphene in GFET. (a) KOH activation; (b) surface modification with APTES; (c) surface modification with glutaraldehyde (GA); (d) immobilization with ADH-specific aptamer and (e) schematic illustration of all stages in surface functionalization of graphene.

Figure 5

The current to voltage (I–V) measurements. (a) prior to surface functionalization; (b) for various ADH concentrations; (c) sensitivity and (d) limit-of-detection.

Figure 6

Specificity analysis of ADH biosensor tested with ADH spiked in phosphate-buffered saline (PBS) buffer, ADH spiked in human serum and other biomolecules.