A triple-channel sensing array for protein discrimination based on multi-photoresponsive g-C₃N₄

Graphitic carbon nitride (g-C₃N₄) as an outstanding photoresponsive nanomaterial has been widely used in biosensing. Other than the conventional single channel sensing mode, a triple-channel sensing array was developed for high discrimination of proteins based on the photoresponsive g-C₃N₄. Besides the photoluminescence and Rayleigh light scattering features of g-C₃N₄, we exploit the new photosensitive colorimetry of g-C₃N₄ as the third channel optical input. The triple-channel optical behavior of g-C₃N₄ can be synchronously changed after interaction with the protein, resulting in the distinct response patterns related to each specific protein. Such a triple-channel sensing array is demonstrated for highly discriminative and precise identification of nine proteins (hemoglobin, trypsin, lysozyme, cytochrome c, horseradish peroxidase, transferrin, human serum albumin, pepsin, and myoglobin) at 1 μM concentration levels with 100% accuracy. It also can discriminate proteins being present at different concentration and protein mixtures with different content ratios. The practicability of this sensor array is validated by high accuracy identification of nine proteins in human urine samples. This indicates that the array has a great potential in terms of analyzing biological fluids. Graphic abstract .