Continuous monitoring of drug effects on complex biological samples by segmented flow chip calorimetry

In the presented paper, the capability of segmented flow chip calorimeters for the analysis of time-dependent pharmaceutical effects on differently complex biological systems is demonstrated. Due to the noninvasive nature of calorimetric measurements, the dynamics of metabolic changes in living material can be analyzed more precisely compared to endpoint methods, in particular in case of highly inhomogeneous sample material. In comparison to batch and conventional flow-through calorimeters, the segmented flow technology enables increased throughput and defined cultivation conditions of the investigated material. Samples of 1 mm 3 of colorectal cancer tissue were treated with 5-Fluorouracil or staurosporine and subsequently analyzed by segmented flow chip calorimetry. The observed dynamics of the drug effects is characterized by defined inflection points in the heat rate curves. All data of the onset time were similar for a given drug. In contrast, the rate of metabolic deactivation of the tissue affected by the treatment was strongly dependent on the biology of the tumor from individual patients. The heat evolution of fibroblast spheroids treated with staurosporine showed a similar dynamics as observed in treated colorectal cancer tissue samples. However, the heat production of synthetic micro-tissues was more uniform than the heat production of the highly inhomogeneous cancer tissue, directly derived from surgical patients. The investigation of the effect of adrenalin and noradrenalin on the metabolism of daphnia demonstrated the excellent real-time capabilities of the used segmented flow chip calorimeter. An increased heat production rate could be measured already few minutes after start of treatment. The small thermal time constant of the calorimeter of only 25 s enabled the detection of drug-caused changes in the motility of the daphnia in a frequency bandwidth of 0.02 Hz.