Biosensing with Nanoparticles as Electrogenerated Chemiluminsecence Emitters

Abstract

Electrogenerated chemiluminescence (ECL), also known as electrochemiluminescence, is the luminescence generated by relaxation of exited-state molecules that are produced during an electrochemically initiated reaction [1]. The phenomenon of ECL has been known for a long time. Reports date back as far as 1927 for the light emission of Grignard compounds at applied potentials [2] and 1929 for the ECL of luminol [3]. Along with subsequent publications concentrated on the investigation of the mechanism and nature of ECL, especially of polyaromatic hydrocarbons (PAHs) and metal complexes [4–6], ECL has now become a very powerful analytical technique and been widely used in the areas of, for example, immunoassay, food and water testing, and biowarfare agent detection [7, 8]. As a method of producing light at an electrode, ECL represents a marriage between electrochemical and spectroscopic methods. This gives ECL many distinct advantages over other spectroscopy-based detection systems. For example, ECL do not involve a light source as fluorescence methods do; thus, the attendant problems of scattered light and luminescent impurities are absent without the presence of a background signal. Moreover, the specificity of the ECL reaction associated with the ECL label and the coreactant species decreases problems with side reactions, such as self-quenching.