Cationic covalent organic frameworks for simultaneous capture and high-performance enrichment of multiple angiotensins and aldosterone in human plasma.

The efficient enrichment and simultaneous detection of trace levels of angiotensin (Ⅰ, Ⅱ, Ⅲ) and aldosterone in plasma pose certain technical challenges. Herein, we propose a novel strategy where a cationic covalent organic framework (Py-BPy2+-COF) was served as an attractive adsorption material for efficient enrichment of angiotensin (Ⅰ, Ⅱ, Ⅲ) and aldosterone. Adsorption experiments and model fitting revealed that Py-BPy2+-COF exhibited adsorption capacities ranging from 5.02 to 26.12 μg g-1 for the four target analytes. The Hirshfeld partition analysis elucidated that the interaction forces of angiotensin and aldosterone with Py-BPy2+-COF originated from electrostatic interactions, π-π stacking and hydrophobic interactions. Py-BPy2+-COF was employed as the sorbent packing in a 96-well plate coupled with liquid chromatography-tandem mass spectrometry, achieving high sensitivity, excellent reproducibility, high recoveries (80.1%-94.9%), low limits of detection (5-50 pg mL-1), and cost-effectiveness, while maintaining high extraction efficiency even after 10 repeated uses. This study provides a novel approach for the detection of angiotensin (Ⅰ, Ⅱ, Ⅲ) and aldosterone in plasma, and demonstrates the potential of cationic COFs as functional materials in biomedical analysis.