A low-cost microBR (microbioreactor) made from PTFE [poly(tetrafluoroethylene)] was used to cultivate a model organism, Pseudomonas aeruginosa DS10-129. The progress of bioprocessing was monitored by comparing the growth of the organism in a microBR, a conventional bench scale bioreactor and a shake flask. Under the microBR conditions, the organism produced 23 mg/ml of pyocyanin that had antimicrobial effects against Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas teessidea and Pseudomonas clemancea. Furthermore, it produced a total of 106 microg/ml of effective biosurfactants consisting of dirhamnolipids (RL2) and monorhamnolipids (RL1). The biosurfactants reduced the surface tension of distilled water from 72 to 27.9 mN/m and emulsified kerosene by 71.30%. The pyocyanin and rhamnolipids were produced during the exponential and stationary phases of growth respectively. The results of the microBR were comparable to those obtained using conventional scale methods.

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A reusable low cost microfluidic cell culture array device (MCCAD) integrated with a six output concentration gradient generator (cGG) and 4×6 arrays of microchamber elements, addressed by a series of row and columnar pneumatically actuated normally closed (NC) microvalves was fabricated for cell-based screening of chemotherapeutic compounds. The poly(dimethylsiloxane) (PDMS) device consists of three layers: fluidic, control and membrane which are held by surface contact and made leak-proof by clamping pressure. The NC valves are actuated by a thick PDMS membrane that was created by a novel method based on the self-assembly of PDMS pre-polymer molecules over a denser calcium chloride solution. The membrane actuated the valves reliably and particulates such as alumina particles (3 µm) and MCF-7 cells (20-24 µm) (2×10(5) cells/mL) were flowed through the valves without causing blockage or leakage and consequently avoiding contamination of the different cell culture elements. The MCCAD was cast and assembled in a standard laboratory without specialist equipment and demonstrated for performing quantitative cell-based cytotoxicity assays of pyocyanine on human breast cancer (MCF-7) cells and assessed for toxic effect on human hepatocyte carcinoma (HepG2) cells as an indicator for liver injury. Then, the MCCAD was demonstrated for sequential drug combinatorial screening involving gradient generation of paclitaxel doses followed by treatment with aspirin doses on the viability of MCF-7 cells. The interaction between paclitaxel and aspirin was evaluated by using the Bliss independence predictive model and results showed reasonable agreement with the model. A robust, portable, easily fabricated and low cost device is therefore shown to conveniently carry out culturing of multiple cell lines for high throughput screening of anti-cancer compounds using minimal reagents.

A prototype membrane aerated polydimethylsiloxane (PDMS) microbioreactor integrated with a photodiode detector was developed for monitoring intracellular green fluorescent protein ultraviolet (GFPUV) expression in Escherichia coli. The developed system is compact, simple and inexpensive and ideal for economical on chip detection of fluorophores in aqueous solution and intracellular GFPUV expression. The detection limit for cell free GFPUV was found to be 4.8 × 10-8 M. Intracellular GFPUV expression in E. coli cells was monitored for 12 h and the lowest detectable signal was recorded from a cell concentration of 2.7 × 10 7 cells/mL with signal to noise ratio (SNR) value of 3. The performance of the photodiode detector was benchmarked with a CCD spectrophotometer and results showed favorable comparison. A miniaturized microbioreactor for monitoring intracellular dynamics in real time is demonstrated.

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