Synergistic TiO₂-doped g-C₃N₄@PoPD nanohybrid: toward efficient biosensing of xanthine

An enzymatic biosensor based on poly-ortho-phenylenediamine (PoPD) coated with graphitic carbon nitride (g-C₃N₄) and titanium dioxide (TiO₂) was developed for the detection of xanthine (Xn). Microscopic and spectroscopic analyses confirmed the successful incorporation of TiO₂ into the g-C₃N₄@PoPD nanohybrid. The resulting nanocomposite exhibited excellent sensing performance, achieving a wide linear detection range from 1 pM to 1 µM and an ultralow detection limit of 0.2 pM. The biosensor demonstrated good stability for up to 5 weeks, high reproducibility, and strong selectivity toward Xn even in the presence of potential interfering analytes. Validation using real samples from Rohu (Labeo rohita) fish further confirmed its potential applicability for xanthine detection in meat freshness assessment.