Enhanced electrochemiluminescence at single lithium iron phosphate nanoparticles for the local sensing of hydrogen peroxide efflux from single living cell under a low voltage

Abstract

The pursuit of strong electrochemiluminescence (ECL) at a low voltage is crucial, but challenging, for further development of ECL based bioanalysis, especially at single cells. In this work, single lithium iron phosphate (LiFePO4, LFP) nanoparticles at the surface of indium tin oxide (ITO) is firstly applied to produce enhanced ECL from luminol and hydrogen peroxide under a low voltage of 0.5 V. Lithium ions from single LFP particles are proposed to be de-intercalated during the charging process and then inserted into ITO to form LiSnO2, in which the oxidation of a luminol derivative (L012) is promoted resulting in an ECL emission at a low voltage. Meanwhile, the transformation of LiFePO4 into FePO4 under this voltage accelerates the generation of oxygen intermediates from hydrogen peroxide, and thus, leads to an elevated ECL intensity. Eventually, the efflux of hydrogen peroxide from single living cells is directly visualized under a voltage of 0.5 V using the ECL imaging approach, which is significantly lower than the previous voltage of 1.0 V. The first coupling of lithium migration in ECL reaction will pave a new direction to improve the ECL emission efficiency, and ultimately, push the development of ECL technology in highly spatial sensing of single cells.