Matrix- Assisted Laser Desorption Ionization Mass Spectrometry Analysis and Imaging of Porcine Brain Tissue Section Using Precoated Nanocarbon-Sodium-Dodecyl Sulfate Composite Matrix

Nanomaterial matrices have unique advantages in small molecule analysis by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). On the basis of comparing different surfactants, a method for pre-coating nanocarbon sodium dodecyl sulfate (SDS) composite matrix was established, which could alleviate the issue of aggregation of nanocarbon particles as a matrix. The experimental results showed that the nanocarbon-SDS composite pre- coated matrix effectively suppressed the background ion peak of the nano matrix, significantly improved the MS peak intensity and signal-to-noise ratio of the tested substance. Under the optimal conditions, cholesterol, 1,2-dipalmitoyl-sn-glyceryl-3-phosphorylcholine- dipalmitoyl-sn-glyceryl-3-phosphorylcholine (DPPC), and triglyceride standards were analyzed, with intra-point- point repeatability (RSD) of MS peak intensity 5% % and inter- point repeatability 7%. % . As to measurement of cyclic adenosine monophosphate and DPPC samples in the range of 0.05-1.0 mg/mL, linear correlation coefficient (R-2) between peak intensity and concentration was greater than 0.993, indicating good quantitative analysis potential. The nanocarbon-SDS composite pre-coating matrix was used for MALDI-MS imaging of pig brain tissue, and the differences in component distribution between pig brain white matter and gray matter were observed, demonstrating the potential of nanocarbon-SDS composite pre- coating matrix for MALDI-MS imaging.