Fluorescence monitoring of capillary electrophoresis
separation of biomolecules with monolithically
integrated optical waveguides
C. Dongre1, R. Dekker1,4, H. J. W. M. Hoekstra1, R. Martinez-Vazquez2, R. Osellame2, R. Ramponi2, G. Cerullo2, R. van Weeghel3, G. A. J. Besselink4, H. H. van den Vlekkert4,
and M. Pollnau1
1
Integrated Optical MicroSystems (IOMS), MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
2
Istituto di Fotonica e Nanotecnologie del CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
3
Zebra Bioscience BV, W. Beverstraat 185, 7543 BK Enschede, The Netherlands
4
LioniX BV, P.O. Box 456, 7500 AH Enschede, The Netherlands E-mail: C.Dongre@ewi.utwente.nl
Femtosecond-laser post-processing is an attractive approach for fast (few minutes/chip) and direct on-chip integration of optical waveguides to transport light along arbitrary 3D trajectories to excite fluorescent-labeled biomolecules in fluidic microchannels. This value addition to device portability in point-of-care applications complements the mature lab-on-a-chip mass-production technologies. Such commercial fused-silica capillary electrophoresis (CE) chips were empowered with monolithically integrated, femtosecond-laser-written waveguide arrays intersecting the separation channel [1]. The inherently aligned 12-micrometer excitation/detection windows enable high-spatial-resolution visualization and monitoring of different fluorescent analytes during CE separation. Wavelength-selective monitoring of on-chip separation of the fluorescent dyes Fluorescein, Rhodamine-B, and Rhodamine-6G has been implemented as a proof of principle. Excitation/detection of fluorescent-labeled DNA molecules during their on-chip separation has also been demonstrated [2], as applicable in diagnostic bioassays to detect genetic disorders, e.g. breast cancer. The DNA amplicon (length ~150bp) was produced by polymerase chain reaction targeting specific, diagnostically relevant regions of the ERBB2 gene, and labeled with the intercalating fluorescent dye SYBR Green. Laser excitation was performed at wavelengths of 543 nm and 488 nm, respectively. It is foreseen in the near future to achieve multi-point, multi-wavelength online monitoring of the CE separation of fluorescent-labeled DNA molecules at low a limit of detection.
References:
1. R. Martinez-Vazquez, R. Osellame, D. Nolli, C. Dongre, M. Pollnau, H.H. van den Vlekkert, R. Ramponi, and G. Cerullo, “Integration of femtosecond laser written optical waveguides in a lab-on-chip”, Lab Chip, in press (2009).
2. C. Dongre, R. Dekker, H.J.W.M. Hoekstra, M. Pollnau, R. Martinez-Vazquez, R. Osellame, R. Ramponi, G. Cerullo, R. van Weeghel, G.A.J. Besselink, and H.H. van den Vlekkert, “Fluorescence monitoring of microchip capillary electrophoresis separation with monolithically integrated waveguides”, Opt. Lett.
33(21), 2503 (2008).
Summary:
Monolithic integration of optical waveguides in a commercial lab-on-a-chip by femtosecond-laser material processing enables arbitrary 3D geometries of optical sensing structures in combination with fluidic microchannels. Integrated fluorescence monitoring of molecular separation, as applicable in point-of-care diagnostic bioassays is demonstrated.
Speaker Biography:
Chaitanya Dongre received his B. Tech. and M. Tech. degrees in Electrical Engineering from the Indian Institute of Technology, IIT Bombay. Following short stays at the International School for Advanced Studies “SISSA”, Trieste, Italy, University of Paderborn, Germany, and the R&D laboratory “SAMEER” of the Indian Ministry of Information Technology, he joined the MESA+ Institute for Nanotechnology, University of Twente, The Netherlands as a Ph.D. student. His research interests include femtosecond-laser material processing, micro-opto-fluidic-integration, and biosensing. He has (co-)authored more than 15 journal & conference papers. He was awarded the first prize for the best contribution at the European Conference on Integrated Optics (ECIO’08), Eindhoven, The Netherlands.
