Multi-color fluorescence detection of ribosomal RNA in micro-channels

A micro fluidic device capable of detecting the abundance of bacteria in an environmental solution is described. The micro channels are made of poly(dimethylsioxane) (PDMS) elastomer integrated with fused silica capillaries coated with Aluminum. The detection of specific bacteria is based on molecular probes (beacons) that emit a fluorescent signal only when hybridized to the target. This method allows hybridization in solution, without immobilization, and avoids washing of the unbound probes. By marking 16S rDNA oligonucleotide probes (different genetic sequences) with different color dyes, and detecting the spectral intensity of light in the micro-channel, different microorganisms can be detected in one sample. Miniaturization of the analytic device allows the use of small quantities of RNA molecules, as target molecules, and improves the detection limits. Future devices should incorporate a parallel array of micro-channels, and enable fast and parallel processing of the molecular signals.