MoS₂-Based NH₃ Sensor for In Situ <i>Helicobacter pylori</i> Detection

Detection of <i>Helicobacter pylori</i> is essential for the prevention of gastric cancer. By detecting the metabolized NH₃, it was able to noninvasively reveal the state of <i>H. pylori</i>; however, it is still a challenge since the metabolized NH₃ concentration is much lower for conventional gas sensors. Herein, we developed a MoS₂-based NH₃ sensor for continuous, real-time monitoring of <i>H. pylori</i> growth. The atomic thin layer and the all-exposed surface of MoS₂ facilitate NH₃ adsorption and charge transferring. A high-response NH₃ sensor was prepared by surface decoration of MoS₂ by depositing metal nanoparticles. The Fe-decorated MoS₂ sensor outperformed with a high response of 40.9% for 5.7 ppm of NH₃ at 25 ± 2 °C, low LOD (6.2 ppb), and long-term stability with a response of 12.5% for 5.7 ppm of NH₃ after 5 months. The Fe-decorated MoS₂ sensor was applied to the detection of <i>H. pylori</i> and the real-time in situ monitoring of its 92 h growth cycle. The NH₃ release curve of the exponential phase during <i>H. pylori</i> growth was continuously monitored, and the NH₃ concentration was quantified. The maximum specific rate of NH₃ release was 0.195 ± 0.005 h^-1, which is well-consistent with the nature of <i>H. pylori</i> growth. This study opens up a technological roadmap for noninvasive detection of <i>H. pylori</i> in the future.