A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride

• A novel photoelectrochemical biosensor is fabricated for kinase activity assay.
• Phosphorylated g-C3N4 is used as the photoelectric conversion material with visible-light activity.
• The high affinity between Zr4+ and the phosphate group causes the assembly of P-g-C3N4 on the substrate peptide.
• The developed method can be applied to detect kinase in real samples.

Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr4+ ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity.

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