Chirality-Endowed Hydrogen-Bonding Network Enabling Long-Range Order and Enhanced Ionic Conductivity for Room-Temperature Chemiresistive CO2 Sensing

High-performance room-temperature CO2 sensors are essential for noninvasive clinical diagnostics, yet achieving high sensitivity in metal-organic frameworks (MOFs) remains challenging due to restricted ionic conduction. Building upon our previous expertise in guest-ion-source assembly, a strategy is proposed to enhance ionic conductivity by constructing long-range order and stable hydrogen-bonding (H-bonding) networks via chiral molecular incorporation. D-Tryptophan (D-Trp) and L-tryptophan (L-Trp) were encapsulated within γ-CD-MOF cavities to serve as chiral ion sources, facilitating the creation of bioinspired anion channels. The results reveal that the superior sensing performance of γ-CD-MOF@D-Trp is attributed to host-guest chiral preference. D‑Trp achieves ordered molecular arrangement via steric hindrance regulation, constructing long‑range order H‑bonding networks to optimize ion hopping pathways and stable sensing channels. The resulting sensor achieves a high response (2.10 toward 1000 ppm CO2), a low practical limit of detection (pLOD) of 10 ppm, and good selectivity. In particular, this work presents superior stability among MOF‑based room-temperature chemiresistive CO2 sensors reported so far, still retaining approximately 90% of its initial value after 35 days. Crucially, the fabricated γ-CD-MOFs@D-Trp-based sensor is preliminarily capable of distinguishing the differences in exhaled CO2 concentration between healthy individuals and lung cancer patients.