Highly sensitive mass spectrometric detection in droplet microfluidics to monitor single cell catalysis and metabolite secretion

基于微滴的微流体技术已经成为众多（生物）化学应用的强大平台技术，从药物分析到微化学转化到单细胞分析。另一方面，质谱（MS）是在分子水平上表征过程的最有力的工具。液滴微流体-质谱技术遇到的主要限制是迄今为止使用的商用同轴鞘流喷雾器用于电喷雾电离（ESI）的检测灵敏度。因此，对低丰度化合物的质谱分析几乎是不可能的。为了克服这些限制，本项目旨在开发先进、高灵敏度和鲁棒性的纳米esi液滴微流体-质谱耦合。纳米流护套液方法将实现稳健、灵活和敏感的方法，因为优化护套液的量很少，而且由于毛细血管的移动，只对水相进行电喷雾。在无护套方法中，将通过集成ESI发射器尖端的无稀释电接触来研究由激光诱导蚀刻产生的单片3d微结构芯片界面。将开发的偶联技术进行实验基准测试，与当前的技术状态进行比较，并应用于监测单细胞催化，代谢物分泌和药物蛋白的强制降解研究，以探索新开发的微滴微流体-质谱技术的可能性和局限性。

Droplet-based microfluidics has become a powerful platform technology for numerous (bio)chemical applications from pharmaceutical assays over microchemical conversions to single cell analysis. On the other hand, mass spectrometry (MS) is the most powerful tool to characterize the processes on the molecular level. The main limitation encountered in the droplet microfluidics-MS technology is the achievable detection sensitivity with the commercial coaxial sheath flow sprayer for electrospray ionization (ESI) used so far. For this reason, MS analysis of low abundant chemical compounds is barely possible. In order to overcome these limitations this project aims at developing advanced, highly sensitive and robust nanoESI droplet microfluidics-MS couplings. A nanoflow sheath liquid approach will enable a robust, flexible and sensitive approach due to low amount of optimized sheath liquid with the idea to electrospray only the aqueous phase due to movable capillaries. In the sheathless approach a monolithic 3D-microstructured chip interface generated by laser induced etching will be investigated by a dilution free electrical contacting of the integrated ESI emitter tip. The developed coupling techniques will be experimentally benchmarked, compared with the current state of the art, and applied to monitor single cell catalysis, metabolite secretion, and forced degradation studies of pharmaceutical proteins in order to explore the possibilities and limitations of the newly developed droplet microfluidics-MS technology.