Evaluation of ruthenium(bpy)(3+,3)-based chemiluminescence detection as a detection strategy for microfluidic devices

Capillary electrophoresis (CE) has become a powerful separation tool due to its high efficiency, resolution potential, relatively short analysis times, low instrumentation cost, and minimal waste production. For CE, only extremely small sample volumes are required. This small sample size has led to CE being a viable technique to integrate with microfluidic devices. However, the characteristics which make CE an attractive separation technique also make detection difficult as the small sample volume requires very sensitive detection. Among the detection methods available for CE, electrogenerated chemiluminescence (ECL) offers low detection limits with simple instrumentation. This detection method is well suited for integration into microfluidic devices. Electrogenerated Ru(bpy)33+-based CL has been used as a detection strategy for FIA, HPLC, and CE to detect a variety of analytes including amines and amino acids. However, ECL Ru(bpy)3 3+- based CL has not yet been integrated with microfluidic devices fabricated from polymer substrates.;The efficacy of a tertiary amine labeling protocol for the detection of proteins and has been evaluated. Two biotin derivatives were synthesized containing a tertiary amine functionality and then incubated with the protein, avidin. The addition of the tertiary amine moiety to biotin made the derivative more sensitive to Ru(bpy)33+-based CL. Quantitative data were obtained as a model of a labeling protocol by varying the number of biotins per avidin. Limits of detection (LOD) for either derivative were determined to be approximately 50 nM, for the lowest concentration studied. The relative luminescence response increased with increasing number of tertiary amine labels per molecule of avidin. The results showed the potential of this approach for the detection of proteins using this tertiary amine labeling methodology.;The integration of Ru(bpy)33+-based CL detection with polymer microfluidic devices has been demonstrated. Two modes of fluid transport were evaluated and a comparison of the quantitative data for both modes provided promising preliminary results. Limits of detection for the different modes were evaluated, as well as the precision of a novel injection method. Although the detection system was not optimized for low light detection, the limits of detection achieved are comparable to published reports using similar off-channel detection methods. To date, there have been no other reports of the integration of Ru(bpy)33+-based CL detection with polymer microfluidic devices fabricated from polydimethyl siloxane.