Ti-Doping Activates Adjacent Zr Sites in Bimetallic MOFs for Cooperative Phospholipid Removals in Human Biomonitoring

The interference of phospholipids in serum poses a critical bottleneck for nontargeted human biomonitoring of chemical hazards. Here, we report a Ti-doping strategy to activate adjacent Zr sites in a bimetallic Zr/Ti metal-organic framework (B-Zr/Ti MOF) for cooperative and efficient phospholipid removal. By precisely engineering the Ti content, the optimal B-Zr/Ti MOF achieves near-complete removal of major phospholipid subclasses while maintaining high recoveries (>50%) for over 500 diverse chemical hazards, even at trace levels (10 ng mL^{- 1}). Combined XPS, FT-IR, and DFT calculations reveal that Ti incorporation modulates the local electronic environment, converting adjacent Zr sites into highly active Lewis acid centers that synergistically anchor phosphate headgroups via inner-sphere coordination. When integrated into a nontargeted LC-HRMS workflow, this material dramatically reduces matrix effects and expands detectable feature coverage. This work establishes bimetallic node engineering as a powerful strategy to overcome matrix interference in exposomics and precision biomonitoring.