Detection of CREB phosphorylation via Zr (IV) ion mediated signal amplification

• A new assay that can detect CREB phosphorylation down to 0.25 nM is developed.
• High sensitivity is attained by Zr4+ mediated signal amplification.
• Assays in human placenta tissues can reliably indicate progress of preeclampsia.

Phosphorylation of protein plays a vital regulatory role in a variety of biological processes. We herein report a novel method to assay the level of phosphorylated cAMP-response element binding protein (CREB) via Zr4+ mediated signal amplification using gold nanoparticle/DNA/methylene blue (GNP/DNA/MB) nanocomposites. In this method the probe DNA immobilized at a gold electrode surface can specifically and efficiently recognize the phosphorylated target protein CREB. Then Zr4+ links the phosphorylated CREB with GNP/DNA/MB nanocomposites by coordinating the phosphate groups on both CREB and the nanocomposites. Since the nanocomposites can provide high sensitivity (limit of detection: 0.25 nM) for the detection, efficient and highly sensitive bioanalysis of the expression level of phosphorylated protein CREB in human placenta tissues has also been conducted in this work. Our method is reported which shows acceptable stability, reproducibility for assaying of the protein phosphorylation states in real biosamples under physiological and pathological conditions with great potential for clinical applications in future.