Dye-Sensitized and Localized Surface Plasmon Resonance Enhanced Visible-Light Photoelectrochemical Biosensors for Highly Sensitive Analysis of Protein Kinase Activity.

A novel visible-light photoelectrochemical (PEC) biosensor based on localized surface plasmon resonance (LSPR) enhancement and dye sensitization was fabricated for highly sensitive analysis of protein kinase activity with ultralow background. In this strategy, DNA conjugated gold nanoparticles (DNA@AuNPs) were assembled on the phosphorylated kemptide modified TiO2/ITO electrode through the chelation between Zr(4+) ions and phosphate groups, then followed by the intercalation of [Ru(bpy)3](2+) into DNA grooves. The adsorbed [Ru(bpy)3](2+) can harvest visible light to produce excited electrons that inject into the TiO2 conduction band to form photocurrent under visible light irradiation. In addition, the photocurrent efficiency was further improved by the LSPR of AuNPs under the irradiation of visible light. Moreover, because of the excellent conductivity and large surface area of AuNPs that facilitate electron-transfer and accommodate large number of [Ru(bpy)3](2+), the photocurrent was significantly amplified, affording an extremely sensitive PEC analysis of kinase activity with ultralow background signals. The detection limit of as-proposed PEC biosensor was 0.005 U mL(-1) (S/N = 3). The biosensor also showed excellent performances for quantitative kinase inhibitor screening and PKA activities detection in MCF-7 cell lysates under forskolin and ellagic acid stimulation. The developed dye-sensitization and LSPR enhancement visible-light PEC biosensor shows great potential in protein kinases-related clinical diagnosis and drug discovery.