We describe here a simple device for dielectrophoretic concentration of marine microalga Karenia brevis nonmotile cells, followed by electric field-mediated lysis for RNA extraction. The lysate was purified using magnetic beads and pure RNA extracted. RNA quality was assessed off-chip by nucleic acid sequence-based amplification and the optimum conditions for lysis were determined. This procedure will form part of an integrated microfluidic system that is being developed with sub-systems for performing cell concentration and lysis, RNA extraction/purification and real-time quantitative RNA detection. The integrated system and its components could be used for a large range of applications including in situ harmful algal bloom detection, transcriptomics and point-of-care diagnostics.

Development of integrated systems for nucleic acid analyses is mainly driven by the requirement for fast and simple clinical and environmental diagnostics. The need for affordable and effective point-of-care diagnosis has inspired an entire field of biotechnology in micro and nano-fluidics. We are developing a microfluidic system that has individual sub-systems for performing cell concentration and lysis, RNA extraction/purification and real-time RNA detection. The system is being developed to analyse the rbcL gene of phytoplankton Karenia brevis, a species responsible for harmful algal blooms. This integrated system will perform sub-cellular analysis of RNA using nucleic acid sequence-based amplification and would be used in large scale biochemical analysis and experimentation. The device could potentially be used for the detection of any species with a known target nucleic acid sequence for in situ environmental monitoring, forensics or clinical diagnostics.