Consolidating Early-Stage Drug Discovery in an Automated Ultrahigh-Throughput Ambient Mass Spectrometry Platform
Abstract: The early drug discovery workflow relies heavily on high-throughput experimentation, both in terms of organic synthesis as well as analysis of complex biosamples. The identification of new biological targets through large-scale biospecimen studies, the generation of large sets of drug candidates and their rapid bioactivity screening, as well as the in vitro and cell-based confirmation of hits followed by lead optimization, all rely on high-throughput strategies that are typically spread out across diverse technologies in specialized facilities. The efficiency of this workflow could benefit from the consolidation of these activities in a single closed-loop platform. Mass spectrometry (MS) is an attractive technique to achieve such consolidation due to the inherent speed of mass analysis; however, this advantage is rarely fully used due to the widespread use of sample purification approaches (e.g. chromatography) before MS.
Here we describe an automated system that achieves the consolidation of the early drug discovery pipeline by leveraging the advantages of desorption electrospray ionization (DESI), an ambient ionization technique that allows for the rapid and direct analysis of complex samples, both in qualitative and quantitative manner, without any need for workup. This system results from the combination of custom and commercial software, robotics and analytical instrumentation and can achieve throughputs better than 1 Hz using high-density arrays (up to 6,144 samples per array) and 50-nL samples (<5 ng analyte). More significantly, the inherent reaction acceleration phenomenon that occurs in microdroplets, such as those generated intrinsically through the DESI process, allows reaction times to be reduced to just milliseconds, effectively providing an on-the-fly synthetic method that can be coupled with in operando MS analysis or nano-microgram scale product collection for bioactivity assessment.
The general workflow of this platform involves:
- Automated sample preparation or manipulation using a fluid handling workstation.
- Generation of microarrays using a pin-tool.
- Automated transfer and analysis of spotted slides using ultrahigh-throughput DESI-MS.
- Real-time processing of the spectral data.
This methodology has been extensively demonstrated for the screening of organic reactions for identification of optimal synthesis conditions and the selective late-stage functionalization of complex molecules as well as for label-free quantitative biological assays using purified targets (e.g. enzymes, receptors), cell cultures, microorganisms or tissue biopsies, all with no sample cleanup. Examples of all these capabilities will be provided and framed within the overall context of drug discovery showcasing a new-generation system built within the ASPIRE initiative of the US National Center for Advancing Translational Sciences as well as a historical recount of the development of this technology.
Bio: Nicolás Morato is a research assistant professor at the Purdue Institute for Cancer Research of Purdue University. He is a trained chemist and engineer, and most of his career has been focused on analytical chemistry, in particular mass spectrometry. He completed his undergraduate studies at Universidad de los Andes (Colombia), and later his Ph.D. and a postdoctoral fellowship at Purdue University under the mentorship of Graham Cooks.
Overall, his research involves the development of strategies for the rapid analysis of complex samples using ambient ionization mass spectrometry. Most of this effort revolves around the development and application of desorption electrospray ionization mass spectrometry (DESI-MS) for high-throughput experimentation in biochemistry, organic synthesis, clinical diagnosis and biomarker discovery with the underlying objective of consolidating this technology as an efficient closed-loop automated platform for early drug discovery. His work in this area has been recognized by several honors including graduate fellowships by Eastman and the ACS Division of Analytical Chemistry as well as the Tomas B. Hirschfeld Scholar Award from FAACS and the Postgraduate Award from IMSF and JMS.


