Oxygen-vacancy-regulated molybdenum oxide nanosheets for a multi-phosphate discriminative colorimetric sensor array

The detection and identification of various phosphates are crucial in disease diagnostics. However, traditional detection techniques often require the development of multi-ion systems, and the complexity of sensor unit fabrication has limited the broad applications of sensor arrays. In this study, we report for the first-time the design of a colorimetric sensor using oxygen vacancy-regulated MoO_x(2 ≤ x ≤ 3) nanosheets. By precisely modulating the concentration of introduced oxygen vacancies, the plasmonic resonance absorption peak of the MoO_x nanosheets exhibited tunable shifts, thereby influencing their optical properties. The addition of phosphate ions with different configurations influenced the light absorption range and the plasmonic peak values of the oxygen vacancy-rich MoO_x sensor array to various extents. Through statistical analysis methods, this sensing array effectively identified ten types of phosphates (i.e., ATP, ADP, AMP, PPi, Pi, UTP, GTP, GDP, GMP, and CTP). The sensor demonstrated excellent detection and discrimination capabilities in both quantitative identification and the recognition of mixed phosphates. The practical application of this sensor array was validated by precisely detecting phosphates in complex systems such as serum. Compared to the previous reports, the fabrication process of the oxygen vacancy-regulated MoO_x nanosheets is simple, the discrimination detection effect is good, and it provides a new approach and method for the design and fabrication of highly efficient sensor arrays.