Scanning Probe Microscopy Characterization of Biomolecules enabled by Mass-Selective, Soft-landing Electrospray Ion...

Area of Science:

• Surface science
• Biophysics
• Analytical chemistry

Background:

• Scanning probe microscopy (SPM) provides atomic-level resolution imaging.
• Traditional sample preparation for SPM, like thermal sublimation, is unsuitable for thermally fragile biological molecules.
• Limitations in sample preparation hinder the analysis of complex biomolecules using SPM.

Purpose of the Study:

• To introduce and discuss electrospray ion beam deposition (ESIBD) combined with low-temperature ultra-high vacuum SPM (LT-UHV SPM) for analyzing complex biological molecules.
• To demonstrate how ESIBD overcomes limitations of thermal sublimation for biomolecule deposition.
• To showcase the potential of ESIBD+SPM for detailed molecular analysis.

Main Methods:

• Utilizing electrospray ionization to generate intact molecular ions from solution.
• Employing soft-landing electrospray ion beam deposition (ESIBD) to transfer mass-selected ions onto surfaces.
• Analyzing deposited molecules using low-temperature ultra-high vacuum scanning probe microscopy (LT-UHV SPM).

Main Results:

• ESIBD enables the deposition of large, thermally fragile biological molecules onto surfaces while preserving their integrity.
• The ESIBD+SPM technique allows for controlled sample preparation with respect to molecular structural integrity, shape, and purity.
• High-resolution imaging of proteins, peptides, DNA, and glycans revealed details of their connectivity, conformation, and interactions.

Conclusions:

• ESIBD+SPM is a powerful sample preparation method for LT-UHV SPM analysis of complex biological molecules.
• This technique significantly expands the analytical capabilities of SPM for biomolecular research.
• Detailed molecular insights previously inaccessible are now achievable for a wide range of biomolecules.