Functionalized Graphitic Carbon Nitride Based Aptasensing Platform for Electrochemical Detection of Helicobacter Pylori

Helicobacter pylori
(
H. pylori)
was initially obtained from gastritis patients, and its infection is mainly responsible for around 80% and over 90% of stomach and duodenal ulcers, respectively. Most screening techniques require advanced instrumentation and skilled operators, resulting in delayed and costly detection. Hence, developing a practical, highly selective, rapid, and simple approach to identifying
H. pylori
is of utmost importance. In pursuit of this objective, we have designed an electrochemical aptasensor utilizing aptamer-target protein interaction, focusing on the virulence factor cytotoxin-associated gene A (Cag A) protein of
H. pylori
. This aptasensor was constructed using organofunctional silane, specifically 3-(aminopropyl)triethoxysilane (APTES), to functionalize graphitic carbon nitride (g-C
₃
N
₄
). The synthesis of g-C
₃
N
₄
was achieved through the thermal pyrolysis of urea. The resulting g-C
₃
N
₄
was subsequently applied on a screen-printed electrode (SPE). The X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, and differential pulse voltammetry techniques were employed to verify both the morphology and structure of the synthesized g-C
₃
N
₄
and the fabricated electrodes. The chemistry of N-(3-Dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC)- N-Hydroxysuccinimide (NHS) was used to link Cag A-specific aptamers to the APTES@g-C
₃
N
₄
/SPE covalently. This was utilized as a modified aptasensing electrode for
H. pylori
-specific Cag A antigen determination. The aptasensor demonstrated a high sensitivity of 1.98
µ
A ng mL
⁻¹
cm
⁻²
and 0.1 to 160 ng mL
⁻¹
of linear detection range. The limit of quantification (LOQ) and limit of detection (LOD) were determined to be 0.056 and 0.017 ng mL
⁻¹
, respectively. In addition to this, the aptasensor demonstrated exceptional specificity against the
H. pylori
toxin Cag A. This method led to the creation of a remarkably stable aptasensor designed for detecting gastric cancer, opening avenues for the advancement of point-of-care devices.