Non-enzymatic electrochemical detection of H2O2 by assembly of CuO nanoparticles and black phosphorus nanosheets for early diagnosis of periodontitis

Periodontitis, as one of the most universal chronic inflammatory diseases worldwide, has raised numerous attentions since its tremendous destructive force against alveolar bone and soft tissue, ultimately leading to the tooth loss. Hydrogen peroxide (H2O2) is a major byproduct during the pathogenesis of periodontitis, which hints that direct and in-situ detection of H2O2 provides an effective way for early diagnosis of periodontitis. Herein, a non-enzymatic and highly electrocatalytic H2O2 biosensor was proposed by using a novel electrode composed of copper oxide nanoparticles (CuO NPs), black phosphorus nanosheets (BP NSs) and chitosan. Owing to the remarkable electrochemical redox capability of CuO NPs and marvelous conductivity of BP NSs, such heterostructure attained enhanced surface adsorption and efficient electron transfer, contributing to ultrasensitive determination of H2O2 in a real-time manner. The synergistic effects of CuO and BP demonstrated supreme electrocatalytic ability with a low practical detection limit (30 nM), excellent sensitivity (138.00 μA mM−1 cm−2), extraordinary selectivity, splendid reusability and long-term stability. In terms of biofluid level, this biosensor achieved feasible detection of H2O2 in saliva and gingival crevicular fluid samples and effectively differentiated patients of periodontitis from healthy people, which lay solid foundation for diagnosis of periodontitis. Referring to cellular scale, such device was successfully implemented to detect H2O2 released from macrophages and gingival fibroblasts, presenting favorable biosensing capability in living cells. Looking forward, this design of CuO/BP sensor could be extended to broader applications in monitoring physiological and dynamic in-clinic pathological processes in other inflammatory diseases.