Electrochemiluminescence

Electrochemiluminescence or electrogenerated chemiluminescence (ECL) is a kind of luminescence produced during electrochemical reactions in solutions.

In aqueous medium, which is mostly used for analytical applications, simultaneous oxidation and reduction of luminescent species is difficult to achieve due to electrochemical splitting of water itself so the ECL reaction with the coreactants is used.

[7] It combines analytical advantages of chemiluminescent analysis (absence of background optical signal) with ease of reaction control by applying electrode potential.

It can be used as monolayer immobilized on an electrode surface (made e.g. of nafion, or special thin films made by Langmuir–Blogett technique or self-assembly technique) or as a coreactant or more commonly as a tag and used in HPLC, Ru tagged antibody based immunoassays, Ru Tagged DNA probes for PCR etc., NADH or H2O2 generation based biosensors, oxalate and organic amine detection and many other applications and can be detected from picomolar sensitivity to dynamic range of more than six orders of magnitude.

Photon detection is done with photomultiplier tubes (PMT) or silicon photodiode or gold coated fiber-optic sensors.

Schematic representation of the "oxidative-reduction" heterogeneous ECL mechanisms for the couple Ru(bpy) 3 2+ /TPrA. The ECL generation is obtained only by TPrA oxidation and involving the homogeneous reaction of the radical cation (TPrA° + ), as proposed by Bard. [ 5 ] The luminophore in the excited state Ru 2+ * relaxes to the ground state and emits photon. Inset image of electrode surface during an ECL emission [ 6 ]