Organic molecule enhanced 1O2 electrochemiluminescence from the phase transformation of amorphous calcium phosphate

Abstract

Organic molecule enhanced the singlet oxygen (1O2) electrochemiluminescence (ECL) generated during the phase transition of calcium phosphates (CaPs) is presented. As a classic precursor of hydroxyapatite (HAP, Ca10(PO4)6(OH)2), amorphous calcium phosphate (ACP) was in-situ assembled on Nafion film (denoted as ACP/Nafion). The electrochemical oxidation peak and ECL phenomenon were observed when the ACP/Nafion electrode was subjected to cyclic voltammetry (CV) scanning in phosphate buffer solution. The characteristic spectrum of 1O2 dimol emission was observed at 634 nm. And the ECL intensity could be markedly increased and stabilized in the presence of organic molecules, e.g., isopropanol (IPA), oxalate (C2O42−) and L-Lysine. The electron spin resonance (ESR) measurement confirmed that a large number of relevant radicals were produced during the electrochemical oxidation, and these radicals are believed to have played the essential role for the 1O2 generation. Based on the enhancement effect, we exploited the feasibility of direct ECL detection of IPA and L-Lysine by using the ACP/Nafion electrode. And the results show that IPA and L-Lysine can be detected in the range 1.0 μM to 1.0 mM and 0.1 μM to 0.1 mM, with a limit of detection (LOD) 0.15 and 0.03 μM respectively for IPA and L-Lysine. Thus present work not only provides insight for the organic molecule enhanced 1O2 ECL, but also shows the potential for the development of widely applicable ECL detection platform based on abundantly available materials.