Field-enhanced graphene fiber arrays reveal serum metabolic alterations in pancreatic cancer.

A laser desorption/ionization mass spectrometry (LDI-MS) method based on laser-induced graphene fibers (LIGF) is developed. LIGF are fabricated in one step via CO2 laser writing on a polyimide film and serve directly as an LDI substrate without modification. Its fibrous structure produces a strong field-enhancement effect in negative-ion mode, promoting deprotonation of acidic metabolites into stable [M-H]- ions and enabling highly sensitive (fmol-level), highly salt-tolerant, low-background, and uniform detection (with a relative standard deviation of approximately 2.26%). Computer-controlled laser scanning allows rapid production of LIGF arrays for high-throughput metabolic fingerprinting. Applied to serum metabolomics of pancreatic cancer (PC), LIGF-LDI-MS analysis of 195 samples (101 PC patients and 94 age-matched controls) yields tentative identification of 109 metabolites, 28 of which show significant inter-group differences, revealing PC-associated metabolic reprogramming. A neural-network model trained on these profiles achieves 88% diagnostic accuracy in blind validation. This work offers an efficient, low-cost strategy for the non-invasive detection of PC and provides insights for designing application-specific, high-performance LDI substrates.