Taurine-modified rice husk silica: characterization and Aminopeptidase-A inhibitory potential

Taurine-functionalized silica materials were prepared from rice husk ash using direct and reflux immobilization strategies and evaluated as potential Aminopeptidase-A (APA)-targeting materials. Successful surface functionalization was confirmed by Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption analysis, and thermogravimetric analysis(TGA). The reflux-derived material exhibited a specific surface area of 5.05 m2/g, while the direct immobilization system showed a surface area of 2.48 m2/g, both displaying mesoporous characteristics. The biological performance was investigated using ultraviolet-visible (UV-Vis) spectrophotometric absorbance data from the inhibition assays under different incubation times and concentrations. Inhibition increased in a concentration-dependent manner, reaching maximum activity at 300 μg/mL. For APA, inhibition was 85.66 ± 0.44% with free taurine; Tau@Si-Ref and Tau@Si-Dir gave 72.77 ± 0.51% and 69.11 ± 0.12%, respectively. Optimal inhibition was observed after 20–30 min depending on the system. Molecular docking analysis supported the experimental findings through favorable interactions of taurine within the APA active site. These results demonstrate that taurine-functionalized rice husk silica represents a promising biofunctional platform for enzyme-targeting applications and highlight the influence of immobilization strategy on biological performance.