Plasmon-enhanced photoelectrochemical monitoring of Ca2+ from living cardiomyocytes

• TiO2@Ag@Ag3PO4 is developed as a photoelectrochemical sensing platform.
• Functionalization of CaM on sensor surface can monitor Ca2+ release from cells.
• Growth of a thin Ag shell enhances photoabsorption and charge transport of TiO2.
• A high sensitivity of 2.3 μM has been achieved for selective detection of Ca2+.

Photoelectrochemical (PEC) biosensing with plasmonic nanoparticles is an attractive detection method due to the combined advantages of photo-excitation and electrochemical detection. In this paper we develop a new nanocomposite, TiO2@Ag@Ag3PO4, as a plasmon-based PEC sensing platform for monitoring Ca2+ release from living cardiomyocytes. This nanocomposite exploits the benefits of TiO2 nanowires for high stability, fast charge transport kinetics, facile surface functionalization, and environment benignity. In addition, the incorporation of a thin layer of silver@silver phosphate (Ag@Ag3PO4) core–shell nanoparticles can enhance the photoabsorption and charge transport of TiO2. The resulting synergistic effects on the composite lead to an excellent PEC sensing performance of Ca2+ ions in both buffer solutions and from living cardiomyocytes.