Photochemically Driven Peptide Formation in Supersaturated Aerosol Droplets

Area of Science:

• Astrobiology
• Chemical Kinetics
• Physical Chemistry

Background:

• Peptide formation is vital for life's origins but energetically difficult in water.
• Abiotic peptide synthesis requires exploring non-standard environments.
• Dicyandiamide (DCD) is a potential prebiotic chemical relevant to early Earth.

Purpose of the Study:

• Investigate abiotic amide bond formation in aerosol droplets.
• Explore the role of dicyandiamide (DCD) in prebiotic peptide synthesis.
• Determine the influence of aerosol properties on reaction kinetics.

Main Methods:

• Utilized optical trapping and electrodynamic balance for droplet analysis.
• Studied highly supersaturated aerosol droplets containing DCD.
• Employed Raman spectroscopy to monitor amide bond formation.
• Performed kinetic modeling to understand reaction mechanisms.

Main Results:

• Observed light-induced amide bond formation in DCD-containing aerosol droplets.
• Demonstrated that reaction rate depends significantly on droplet size.
• Identified a photochemical product of DCD self-reaction as the likely driver.
• Showcased aerosol particles as viable microreactors for peptide synthesis.

Conclusions:

• Atmospheric aerosols can serve as environments for prebiotic peptide synthesis.
• Photochemistry within aerosols, driven by compounds like DCD, can overcome energetic barriers.
• Findings offer insights into the origins of life and early Earth chemistry.