Bioaffinity Mass Spectrometry Screening Using Droplet-Based Microfluidics

Bioaffinity mass spectrometry screening is a novel approach using non-denaturing electrospray ionization (ESI) mass spectrometry (MS) in identifying drug leads. This screening technique can detect and preserve noncovalent protein-active drug ligand complexes under different physiological conditions. Although there are many successful screening campaigns employing this technique, the big challenge of the screening is the reduction of sample volume needed. We demonstrate in this paper that analysis of samples can be performed using droplet-based microfluidics. Droplets of samples to be screened are formed and delivered directly into the electrospray emitter of a Fourier Transform mass spectrometer. The results show that a MS instrument with a conventional ESI source can clearly detect the samples and distinguish it with the separating oil phase. The proposed technique opens the possibility of bioaffinity mass spectrometry screening of small samples with a simple microfluidic device.