Spray Mechanism of Contained-Electrospray Ionization

Area of Science:

• Analytical Chemistry
• Biochemistry
• Physical Chemistry

Background:

• Contained electrospray ionization (ESI) is a technique for generating gas-phase ions from liquid samples.
• Controlling the state of biomolecules (native vs. denatured) in the gas phase is crucial for structural analysis.
• Existing methods often require bulk-phase modifications of the analyte solution.

Purpose of the Study:

• To investigate the analytical characteristics of contained ESI for controlling biomolecular ion states.
• To explore the real-time modification of charged microdroplets within the ESI ion source.
• To understand the droplet dynamics and reactivity during the ionization process.

Main Methods:

• Utilized contained electrospray ionization (ESI) with real-time droplet modification in an integrated cavity.
• Employed high-speed camera imaging to observe droplet formation and dynamics.
• Analyzed myoglobin charge state distribution and apo-myoglobin content.
• Measured ion mobility drift time profiles under varying spray conditions.

Main Results:

• Demonstrated that contained ESI can generate native versus denatured biomolecular gas-phase ions without bulk modifications.
• Observed discrete droplets and liquid films within the cavity, with droplet speeds of 8 mm/s at 20 psi N2.
• Provided evidence for highly reactive charged droplets based on myoglobin analysis and ion mobility data.
• Gained mechanistic insights into vapor-phase reagent capture and droplet dynamics.

Conclusions:

• Contained ESI offers a versatile platform for controlling biomolecular states in the gas phase.
• The real-time modification within the ion source cavity is key to achieving different denaturation levels.
• This technique enhances the potential for native and denatured biomolecular analysis using mass spectrometry.