In-Source Photoderivatization-Enhanced Neurometabolic Profiling Deciphers Vascular Cognitive Impairment

Neurometabolic profiling in population samples across different stages of vascular cognitive impairment (VCI) holds great promise for elucidating the disease's pathogenesis. However, high-throughput neurometabolic profiling remains challenging due to the limited detection of low-abundance metabolites with poor ionization efficiency. Here, we present a novel photoreactive probe, 5-methoxy-2-nitrobenzaldehyde, combined with TiO₂ P25, to create a mass spectrometry in-source photoderivatization (MSIPD) platform for neurometabolic profiling, with a focus on enhancing the detection of neurotransmitters (NTs). This platform allows for covalent and nanosecond laser-triggered derivatization of monoamine NTs and a 2-fold increase in metabolite coverage compared to underivatized samples, using laser desorption/ionization mass spectrometry (LDI-MS). Our approach demonstrates high derivatization efficiency (over 93%), high reproducibility (≤8.2%), minimal sample consumption (∼1 μL), and rapid analysis speed (∼5 s per sample), without complex sample pretreatment. Application to CSF from 103 VCI patients and 100 controls revealed 12 significantly altered neuro-metabolites. An additional cohort of 131 VCI patients stratified by cognitive status showed stage-dependent alterations, including decreased histamine, histidine, phenylalanine, and homovanillic acid in severe cases, corroborated in a mouse model of cerebral ischemia. These findings underscore NT metabolic dysregulation in VCI pathogenesis and establish MSIPD as a powerful tool for translational neurometabolic profiling.