Dual-point dual-wavelength fluorescence monitoring of DNA separation in a lab on a chip

Abstract

We present a simple approach in electrophoretic DNA separation and fluorescent monitoring that allows to identify the insertion or deletion of base-pairs in DNA probe molecules from genetic samples, and to perform intrinsic calibration/referencing for highly accurate DNA analysis. The principle is based on dual-point, dual-wavelength laser-induced fluorescence excitation using one or two excitation windows at the intersection of integrated waveguides and microfluidic channels in an optofluidic chip and a single, color-blind photodetector, resulting in a limit of detection of ~200 pM for single-end-labeled DNA molecules. The approach using a single excitation window is demonstrated experimentally, while the option exploiting two excitation windows is proposed theoretically.

Femtosecond laser microstructuring: an enabling tool for optofluidic lab‐on‐chips

“…Femtosecond waveguide writing, allowing the fabrication of several parallel waveguides which can interrogate the microchannel contents at multiple points, provides an effective solution to this problem. Here we propose a simple method for spatial and wavelength duplexing, which applies dual-point, dual-wavelength detection from a single detection window (DW) [92]. It does not require any external apparatus to separate the wavelengths, thereby allowing for fluorescence detection with a single, ultrasensitive PMT.…”

“…The two labeled DNA molecules were mixed and the resulting polychromatic mixture was resolved into the individual monochromatic DNA components by dual-point, Figure 11 (online color at: www.lpr-journal.org) Layout of the optofluidic chip indicating the microfluidic reservoirs, channels, and the DW, comprising two waveguides crossing the MCE separation channel perpendicularly in plane [92].…”

Femtosecond Laser 3D Fabrication in Porous Glass for Micro- and Nanofluidic Applications

“…[67]. For example, integration of optical waveguides into a commercially produced CE device has been demonstrated by femtosecond laser direct writing, showing enhanced functionality and ease of operation [68]. Nevertheless, in this example, the CE device is prefabricated using traditional lithography technology, due to the difficulty in forming homogeneous large-scale microfluidic network embedded inside glass with traditional femtosecond laser micromachining techniques.…”

A hybrid silicon-PDMS optofluidic platform for sensing applications

“…For detection, a precise alignment of waveguides and microfluidic channels is required to probe very small volumes of analyte with high accuracy. Monolithic integration of micro-channels and optical waveguides has been used to improve sensitivity, providing a high level of integration and avoiding optical-fiber alignment problems [7][8][9][10][11][12][13]. Optofluidic waveguides are a highly promising alternative to conventional solid-core waveguides for high-sensitivity detection [14][15][16].…”