ToF-SIMS lipidomic data for lipid profiles of Extracellular vesicles and Parent Bacteria

For these experiments, we utilized a reflectron-type time-of-flight secondary ion mass spectrometer (ToF-SIMS V, ION-TOF GmbH, Münster, Germany) equipped with a bismuth liquid metal ion gun. The primary ion source consisted of pulsed Bi₃⁺ clusters at 30 keV with an ion current of approximately 0.61 pA.

Positive secondary ions with mass-to-charge ratios (m/z) ranging from 1 to 900 were collected from individual 150 μm × 150 μm areas. Mass spectra were internally calibrated using H⁺, H₂⁺, CH⁺, CH₂⁺, CH₃⁺, C₂H₅⁺, C₃H₂⁺, and C₃H₅⁺ peaks, with normalization based on the total dose deposited on the surface.

The Bi₃⁺ primary ion beam was rastered randomly over a 128 × 128 pixel grid. To neutralize surface charge during analysis, a low-energy electron flood gun was activated.

During static analysis, the probability of a single primary ion striking the same point on the sample surface more than once was negligible. Total ion doses were maintained below the static acquisition limit, with a uniform dose of 1 × 10¹² ions/cm² applied across all surface analyses.

For data processing, the average intensity values and standard deviations were calculated from eight measurements per sample.