Figure 3
From: Covalent Epitope Decoration of Carbon Electrodes using Solid Phase Peptide Synthesis
Detection of photoinduced electrical potentials near quantum dot surfaces and chemical fluorophores. (a) Cuvette filled with deionized water, containing the labeled surface-tagged graphite and leads connected to the sample and the water. Light path restricted by Faraday cage is shown. (b) Schematic of the full electronic setup, including sample and leads in Faraday cage, amplifier, and oscilloscope. As shown, light is delivered as a pulse of uniform intensity, and the oscilloscope returns peaks at times when a voltage is induced and current flows, i.e. when light intensity changes. Signals were amplified with gain of 1000–2500. Photoinduced electrical potential traces were obtained with irradiation by a broad-spectrum quartz-halogen lamp for (c) biotin-functionalized graphite incubated with streptavidin-coated quantum dots (red) and His-tag antibody-coated quantum dots (olive), (d) His-tag-functionalized graphite incubated with His-tag antibody-coated quantum dots (red) and streptavidin-coated quantum dots (olive), and (e) HA-tag-functionalized graphite incubated with fluorophore-coated HA-tag antibodies (red) and His-tag antibody-coated quantum dots (olive). Photoresponse is evident when binders and surface modifications are paired correctly, while minimal to no signal is detected in mismatched surface-binder pairs. The corresponding type of graphite functionalization is indicated in italics.
