Microfluidic-mass spectrometry analysis of blood-brain barrier transport using engineered microparticle interfaces

The blood-brain barrier (BBB) is vital for maintaining central nervous system (CNS) homeostasis but represents a formidable obstacle to drug delivery, underscoring the need for physiologically relevant in vitro models for CNS drug screening. However, existing in vitro BBB models remain limited in their ability to simultaneously recapitulate multicellular architecture, spatial anisotropy, and dynamic transport behavior while enabling real-time, quantitative analysis. Here, we present an integrated microfluidic-mass spectrometry platform that utilizes engineered BBB particles (BBBps) as a functional analytical interface to enable dynamic, in situ monitoring of BBB transport and metabolism. Using a microfluidic-aerosol hybrid process, we generate multicompartmental microparticles featuring a Matrigel-modified rough surface that enhances endothelial adhesion and tight junction formation, while their cores co-encapsulate microglia, neurons, and astrocytes to establish controlled neurovascular interactions. The BBBps exhibit size- and lipophilicity-dependent permeability, hypoxia-responsive antioxidative protection, and barrier-limited metabolism of salidroside. Real-time analysis with a Chip-MS system further reveals attenuated efflux of glutamate and lactate, confirming barrier integrity and metabolic regulation. This layered design of the micro-blood-brain barrier, combined with Chip-MS analysis, provides a scalable and functionally faithful in vitro model platform for studying drug transport, metabolism, and neurovascular studies.