Microchip Capillary Electrophoresis with Solid-State Electrochemiluminescence Detector

Abstract

We report microchip capillary electrophoresis (CE) coupling to a solid-state electrochemiluminescence (ECL) detector. The solid-state ECL detector was fabricated by immobilizing tris(2,2'-bipyridyl)ruthenium(II) (TBR) into an Eastman AQ55D-silica-carbon nanotube composite thin film on an indium tin oxide (ITO) electrode. After being made by a photolithographic method, the surface of the ITO electrode was coated with a thin composite film through a micromolding in capillary (MIMIC) technique using a poly(dimethylsiloxane) (PDMS) microchannel with the same pattern as an ITO electrode. Then the TBR was immobilized via ion exchange by immersing the ITO electrode containing the thin film in TBR aqueous solution. The whole system was built by reversibly sealing the TBR-modified ITO electrode plate with a PDMS layer containing electrophoresis microchannels. The results indicated that the present solid-state ECL detector displayed good durability and stability in the microchip CE-ECL system. Proline was selected to perform the microchip device with a limit of detection of 2 microM (S/N=3) and a linear range from 25 to 1000 microM. Compared with the CE-ECL of TBR in aqueous solution, while the CE microchip with solid-state ECL detector system gave the same sensitivity of analysis, a much lower TBR consumption and a high integration of the whole system were obtained. The present system was also used for medicine analysis.

Effects of Divalent Metal Ions on Electrochemiluminescence Sensor with Ru(bpy)32+ Immobilized in Eastman‐AQ Membrane

“…Cyclic voltammetry (CV) experiments in 50 mM phosphate buffer (pH 7.5) were performed to study the electrochemical behavior and ECL activity of Ru(bpy) 3 2þ after entrapment in the AQ/CNT composition film. The characterized reversible redox peak of Ru (bpy) 3 2þ can be observed with the anodic peak at 1.2 V due to the oxidation of Ru(bpy) 3 2þ and cathodic peak at 1.1 V of Ru(bpy) 3 3þ reduction, and also the oxidation peak current is proportional to the square root of scan rate, indicating that Ru(bpy) 3 2þ obeys diffusion process in AQ film, which is accordant with the previous report [10]. With 1 mM proline (an ECL coreagent of Ru(bpy) 3 2þ ) in the detection cell, high and stable ECL emission was obtained as shown in Figure 1.…”

“…ITO electrodes were dried under nitrogen stream. Eastman AQ55D and 0.1 mg/mL carbon nanotube (CNT) were blended (1 : 1, v/v), and a 5-mL aliquot of the mixture was dripped on ITO electrode and let to dry at room temperature [10]. The AQ modified ITO electrode was placed in 1 mM Ru(bpy) 3 2þ solution for 30 min to incorporate Ru(bpy) 3 2þ into the composite film.…”

Tris(2,2′‐bipyridyl) Ruthenium(II) Doped Silica Film Modified Indium Tin Oxide Electrode and Its Electrochemiluminescent Properties

“…2,3 Compared with ECL system in solution, 4 the immobilization of Ru(bpy) 2＋ 3 on electrode surfaces has been widely studied because of several advantages, such as reducing the consumption of expensive luminescent reagent, simplifying experimental design and its compatibility with microchip technique. 5 Quiet a lot of different methods have so far been employed to immobilize Ru(bpy) 2＋ 3 on a solid surface, such as Langmuir-Blodgett technique, 6 self-assembly technique, 7 electrostatic attachment 8 and sol-gel entrapment. 9 Owing to their similarity to bulk sol-gel materials, sol-gel silica films have been commonly used as matrices for a great deal of biomacromolecules, 10 molecular assemblies, 11 and functional molecules.…”

Sacrificial layer microfluidic device fabrication methods

“…The logical combination of these with thin-film methods will be critical for the integration of electrical and fluidic control to form micro-total analysis systems (μ-TAS). Indeed, thin-film methods have enabled the integration of many components, such as electrodes [7,8], heaters [9,10], optical sources [11,12], waveguides [13], filters [14] and detectors [14][15][16] in fluidic systems. For example, gold thin-film electrodes have been used in microchips for both in-channel and end-channel amperometric detection [7].…”