Facile synthesis of ZnS nanobowl arrays and their applications as 2D photonic crystal sensors

Large-area ZnS nanobowl arrays with a monolayer inverse opal structure were synthesized facilely by nanosphere lithography at solution surface (NSLSS) through direct solution deposition. It was shown that the well-defined ZnS nanobowl arrays resulted from preferential deposition of ZnS at the polystyrene sphere-solution interface. Owing to the 2D periodic structure of the hexagonally ordered nanobowl arrays and the high refractive index of ZnS, the as-prepared ZnS nanobowl arrays showed intensive structural colors and tunable photonic band-gap properties. These ZnS nanobowl arrays are able to act as effective, fast-responsive 2D photonic crystal sensors based on the refractive index changes because of their easy accessibility for both solvents and analyte molecules. The as-prepared ZnS nanobowl arrays can be used as sensitive 2D photonic crystal sensors for fast detection of organic solvents and for visual oil sensing through color changes. After surface functionalization, the ZnS nanobowl arrays can be used as effective 2D photonic crystal biosensors for sensitive detection of avidin molecules with low detection limits (less than 100 pM) and broad working range.