Multiplexed and fully automated detection of metabolic biomarkers using microdialysis probe.

We report here, the design and development of an automated near real-time continuous detection system for lactate, glutamate, pyruvate and glucose using microdialysis probe. The system developed can automatically push perfusate through microdialysis probe (20, 100 and 1000 kDa MWCO cutoff probe) at low to medium flow rate of 0.5-2 μL/min with almost 100% fluid recovery. The microdialysate collected from the probe is analyzed automatically for these four metabolite biomarkers. It operates in a continuous mode with measurements of all four biomarkers once every 20 min. The dynamic range for these different markers covers the entire clinical range of traumatic brain injury. The prototype shows a low variation of ~ 7-10% across the entire clinical range for all the biomarkers with fairly good accuracy of ~95%. The instrument canrun continuously for 24 h without user intervention. With a long tubing of 1 m to and from the microdialysis probe and associated dead volume, the total lag time for actual event at the probe site versusreported concentration is roughly 1 h.