A peroxidase-mimicking Zr-based MOF colorimetric sensing array to quantify and discriminate phosphorylated proteins

Phosphorylation is a common process for regulating protein functions. Studies have confirmed that many human diseases are associated with the abnormal phosphorylation of proteins. Hence, uncovering the phosphorylation state of proteins turns to be of much importance for biomedicine and clinical practice. In this work, we report a simple but efficient colorimetric sensor array for the quantification and identification of phosphorylated proteins by using a Zr-based MOF as a peroxidase mimic. Thanks to its unique dipyridyl-based ligands, the proposed MOF is able to exhibit favorable catalytic activity to stimulate the chromogenic reaction of H₂O₂ and 3,3',5,5'-tetramethylbenzidine. When phosphorylated proteins are in presence, they can anchor onto the nanozyme surface via the strong interaction between phosphate groups in proteins and Zr nodes in the MOF, resulting in the inhibition of the nanozyme's activity and the suppression of the chromogenic reaction. Based on this principle, our colorimetric sensor array enabled the facile quantification of phosphorylated proteins. Given that proteins with different phosphorylation states would affect the catalytic activity of the MOF nanozyme in different degrees, we further integrated the array with principal component analysis for the successful identification of phosphorylated and non-phosphorylated proteins.