Electrochemiluminescence (ECL)

Current Researchers: Kyle Bake, Christopher Lafratta, Matthew Symer

Microwire Electrode Arrays

We recently employed the sequential deposition of gold in capillaries to produce self-assembled three-dimensional gold microtubes, hollow gold microwires ( i.e., gold microtubes sealed with gold on both ends), and microtube and microwire arrays with unprecedented aspect ratios. These conductors behave as ring or disk microelectrodes and microelectrode arrays and represent a new unique platform for electrochemical analysis, as they similar in form and function to conventional macro and microelectrodes; slender glass cylinders with embedded wires that may be polished for reuse. Sequential deposition is a versatile fabrication technique, as it can be used to produce microelectrodes and arrays of various diameters and geometries, by varying the capillary diameter and spacing of the preformed substrate.

Graduate student Kyle Bake, postdoctoral associate Chris LaFratta, and Tufts undergraduate Matthew Symer are continuing work on the electrochemiluminescence (ECL) arrays project funded by the NSF.  These unique arrays use an electrical potential to generate light from a ruthenium luminophore. The ruthenium complex emits light when an electrical potential is applied in the presence of a coreactant.  Labels of ruthenium bipyridine, Ru(bpy)3+2, can be easily attached to biological molecules such as DNA and proteins. The primary advantage of the ECL method is the extremely low background signal.  The reaction is performed in the dark, so the detected photons come only from the electrochemical reaction.­

Currently, Kyle is optimizing the quantum efficie­­ncy of the system by adjusting experimental conditions, such as buffer components and ­­concentrations.  Chris and Matt, along with a student from Malden High School, Varandt Khodaverdian, have continued David Monk's work with electroless deposition of gold in capillaries to be used for the array.  Chris is also collaborating with electrical engineers from Tufts to fabricate a microchip that will allow electrical interrogation of individual beads on the array.

Recently, ruthenium labeled anti-mouse IgG antibodies have been detected using mouse IgG coated beads.  Kyle, Chris, and Matt plan to continue developing bead-based sandwich assays for proteins and DNA detection by ECL, which they will then transition to multiplexed ECL detection.

 

Figure 1 Schematic depiction of sequential deposition of gold

Figure 2 Selection of images of gold-filled microarrays (TOP) with comparison of empty and filled capillaries (BOTTOM)

False-colored Bead Array