Online Monitoring of Lactate Efflux by Multi-Channel Microfluidic Chip-Mass Spectrometry for Rapid Drug Evaluation

An online multichannel microfluidic chip-mass spectrometry (MS) platform was developed for cell metabolism studies. Paper-spray ionization was employed for microsampling from different microchannels and, at the same time, the interface for direct MS analysis without any sample pretreatment. Near-real-time MS sensing of lactate in different microfluidic channels could be achieved in a preprogrammed and automatic manner. Influences of hypoxia on lactate efflux from normal cells and cancer cells, as well as the differential inhibitory effects and dose–response information on α-cyano-4-hydroxycinnamate on cancer cells of different types were exhibited. The potential of further coupling MS, complementary to optical and electrochemical techniques, to microfluidic devices for cell studies was thus demonstrated.