Evolution of nanomaterial electrochemiluminescence luminophores towards biocompatible materials

Electrochemiluminescence (ECL) is a powerful electrochemical technique for the detection and quantification of molecules, both synthetic and biological in origin. Traditional ECL luminophores are based on organic or organometallic compounds, however nanoparticle-based materials offer the benefits of tuneable wavelengths and narrow emission profiles. Materials based on cadmium have been the most extensively studied for ECL nanoparticles to date. Cadmium based nanoparticles exhibit high levels of toxicity thereby impacting their suitability for mass produced sensing applications. As such, alternative materials with reduced toxicities are required. This review focuses on the innovations and applications of low toxicity semi-conductor quantum dots (SCQDs) utilised as ECL luminophores within biosensors. These materials include silver, copper, zinc, tin, silicon and germanium. This contribution presents an evaluative overview of these materials for use as ECL luminophores in terms of toxicity, tunability of emission, potential for amplification, and water dispersibility. Capacity for functionalisation and multiplexing potential are also explored.