Revealing Structure and Localization of Steroid Regioisomers through Predictive Fragmentation Patterns in Mass...

Area of Science:

• Biochemistry and Molecular Biology
• Analytical Chemistry
• Neuroscience

Background:

• Steroids play crucial roles in biological processes, making their identification and mapping in tissues vital for biomarker discovery, disease progression studies, and therapeutic development.
• While mass spectrometry (MS) is a powerful tool for steroid analysis, accurately imaging and annotating steroid isomers, particularly regioisomers, remains a significant challenge.

Purpose of the Study:

• To develop a novel, highly specific method for the imaging and annotation of steroid isomers in biological tissues.
• To overcome the limitations of current techniques in distinguishing between structurally similar steroid isomers without extensive sample preparation or specialized equipment.

Main Methods:

• A new method utilizing the fragmentation of silver-cationized steroids in tandem mass spectrometry (MS/MS) was developed.
• This approach relies on distinctive and consistent fragmentation patterns generated by silver adducts to achieve regioisomeric specificity.
• The method was applied to visualize steroid and steroid isomer distributions in mouse brain tissue using silver-doped pneumatically assisted nanospray desorption electrospray ionization mass spectrometry imaging (Ag-nanoPnP-DESI-MSI).

Main Results:

• The developed MS/MS method provides distinctive fragmentation patterns for silver-cationized steroids, enabling confident annotation at the regioisomeric level.
• The technique successfully identified and mapped steroid and steroid isomer distributions in mouse brain tissue.
• The method requires no prior derivatization, separation, or instrumental modification, demonstrating its simplicity and flexibility.

Conclusions:

• This novel silver-cationization fragmentation approach offers a simple, flexible, and inexpensive solution for confident steroid isomer annotation and imaging in tissues.
• The method's ease of adaptation suggests it will be widely adopted by the scientific community for advancing steroid research.
• The successful visualization of steroid isomer distributions in mouse brain tissue highlights its utility in biological and biomedical applications.