High-Throughput Analysis of Biomolecules with Acoustic Ejection Mass Spectrometry

In recent decades, mass spectrometry (MS) has been widely used for the analysis of biomolecules such as proteins and nucleic acids, due to its high specificity and sensitivity, where liquid chromatography (LC) has been the primary sample introduction method to the MS with electrospray ionization (ESI) in the negative mode. However, the required time for analyzing a sample is typically longer than 30 sec. In order to support the large sample amount, an analytical platform with a significantly faster sample read-out speed is necessary.
Acoustic ejection mass spectrometry (AEMS) is an ESI-MS-based platform for high-throughput MS. It employs acoustic droplet ejection (ADE) to eject nanoliter samples onto an open-port interface (OPI), which transports them to the ESI ion source. Coupled with high-resolution MS like quadrupole time-of-flight (QTOF), AEMS achieves rapid one-second-per-sample analysis of various biomolecules.
In the first case study, we demonstrate the high-throughput covalent binders screening. AEMS was utilized successfully for a 10,000-scale covalent binder screening. The analysis was direct from the complex sample buffer (with more than 100 mM salts) in the 1536-well format. The robust Z’ approximately 0.8 was maintained for the entire screening for the 2.3% hit rate. Low false positive and false negative was demonstrated by comparing with the LC-MS platform.
In another case study, the AEMS-based method is utilized for the high-throughput characterization of on-DNA reactions for the assessment of DNCLs samples. The sample processing speed is as fast as 1-sec-per-sample, and the on-DNA reaction yield could be accurately determined directly from the high-density well-plates without sample preparation. In addition, the optimization of ion pairing agents that caused system contamination could be avoided.