Laser-induced graphene arrays for high-throughput metabolic profiling reveal serum metabolic alterations in colon cancer.

Given the invasiveness of colonoscopy and the limited sensitivity and specificity of carcinoembryonic antigen for colon cancer detection, we developed a laser desorption/ionization mass spectrometry (LDI-MS) method based on a polyethersulfone film-based laser-induced graphene (PES-LIG) array. The PES-LIG is fabricated by one-step CO2 laser scribing on a PES film and can be directly used as an LDI substrate without any modification. Its layered structure facilitates the desorption/ionization of small-molecule metabolites, enabling uniform detection (RSD = 4.12%) with fmol-level sensitivity, high salt tolerance (S/N = 5319.8 for 1 nmol cellobiose in saturated NaCl solution), and low background. This method requires no matrix mixing, and a single circular LIG spot of 3 mm diameter can be produced in only ∼12 s. In a single experiment, a single PES film (76 mm × 25 mm) yielded a total of 94 LIG spots, with a material cost of only ∼0.04 USD. Thus, this approach enables rapid and high-throughput mass spectrometric analysis. Through computer-controlled laser scanning, PES-LIG arrays can be rapidly prepared and were applied to serum metabolomics of colon cancer. A total of 209 samples (106 colon cancer patients and 103 age-matched healthy controls) were analyzed, and 18 metabolites exhibited significant intergroup differences, revealing colon cancer-associated metabolic reprogramming. A neural network model constructed from these metabolic fingerprints achieved a diagnostic accuracy of 98.3% in blind validation. This work provides a low-cost, high-throughput strategy for non-invasive detection of colon cancer and offers a new high-performance substrate for LDI-MS technology.