Enhanced Detection of Escherichia coli Lipids and Proteins Using Graphene-Polyglycerol Amine via Mass Spectrometry

The accurate and rapid identification of bacterial pathogens poses a significant challenge in clinical diagnostics, environmental monitoring, and microbial research. Lipidomics and proteomics serve as powerful methodologies for bacterial characterization; however, the complexity of biological matrices and the low abundance of bacterial lipids often limit effective detection. This study introduces graphene-polyglycerol amine (G-PGA) as a novel nanomaterial that enhances the selective trapping and detection of Escherichia coli (E. coli) using desorption electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The antimicrobial properties of G-PGA reveal a minimum inhibitory concentration (MIC) of 250 μg/μL and a minimum bactericidal concentration (MBC) of 500 μg/μL. Optimal sonication conditions (10 min) maximize G-PGA's surface activity, facilitating effective bacterial trapping while maintaining cellular integrity, as confirmed by scanning electron microscopy and atomic force microscopy. Molecular docking simulations show a strong affinity between G-PGA and the β-barrel assembly machinery (BAM) proteins of E. coli, suggesting potential disruption of critical bacterial processes. Preconcentration with G-PGA significantly improves detection sensitivity and signal-to-noise ratio in mass spectrometry analyses, highlighting its potential as a transformative tool for rapid, sensitive, and highly specific bacterial identification in lipidomics and proteomics.