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.