High Ionic Strength Enhances the Anti-Pepsin Activity of Titanium Dioxide Nanoparticles

Gastro-esophageal reflux disease (GERD) is a state that evolves when there is a return of acid and pepsin enzyme into the esophagus. Inhibition of pepsin enzyme is one of the strategies used successfully for the treatment of GERD. Titanium dioxide nanoparticles (TiO₂ NPs) are among the safest nanoparticles (NPs) that can be used inside the human body. The aim of the present study is to use TiO₂ NPs as an inhibitor for the pepsin enzyme as a new treatment for GERD. The activity of pepsin before and after the addition of certain amounts of the NPs to the reaction mixture was measured spectrophotometrically.  These experiments were repeated at different temperatures and different ionic strengths. The Michaelis constant (K_m) and maximum velocity (V_max) of the pepsin catalyzed reactions were calculated from the Lineweaver-Burke plots. The results revealed a significant reduction in the pepsin activity by TiO₂ NPs. Both K_m and V_max are changed after inhibition indicating a mixed inhibition of pepsin activity. The result also showed that the combination of high ionic strength and TiO₂ NPs causes a complete inhibition of pepsin activity. It can be concluded that the best condition for inhibition of pepsin activity is by using a combination of TiO₂ NPs and high concentration NaCl at 37°C.