A Dual Sensing Platform for Human Exhaled Breath Enabled by Fe-MIL-101-NH2 Metal-Organic Frameworks and its Derived Co/Ni/Fe Trimetallic Oxides.

Limited by the insufficient active sites and the interference from breath humidity, designing reliable gas sensing materials with high activity and moisture resistance remains a challenge to analyze human exhaled breath for the translational application of medical diagnostics. Herein, the dual sensing and cooperative diagnosis is achieved by utilizing metal-organic frameworks (MOFs) and its derivative. The Fe-MIL-101-NH2 serves as the quartz crystal microbalance humidity sensing layer, which exhibits high selectivity and rapid response time (16 s/15 s) to water vapor. Then, the Co2+ and Ni2+ cations are further co-doped into Fe-MIL-101-NH2 host to obtain the derived Co/Ni/Fe trimetallic  oxides (CoNiFe-MOS-n). The chemiresistive CoNiFe-MOS-n sensor displays the high sensitivity (560) and good selectivity to acetone, together with a lower original resistance compared with Fe2 O3 and NiFe2 O4 . Moreover, as a proof-of-concept application, synergistic integration of Fe-MIL-101-NH2 and derived CoNiFe-MOS-n is carried out. The Fe-MIL-101-NH2 is applied as moisture sorbent materials, which realize a sensitivity compensation of CoNiFe-MOS-n sensors for the detection of acetone (biomarker gas of diabetes). The findings provide an insight for effective utilization of MOFs and the derived materials to achieve a trace gas detection in exhaled breath analysis.

Balancing the thickness of sensitizing and inert layers in neodymium-sensitized tetralayer nanoconstructs for optimal ultraviolet upconversion and near-infrared cross-linked hydrogel tissue sealants.

Tuning the configuration of lanthanide-doped upconversion nanoparticles (UCNPs) has been proven to be an effective approach to enhance upconversion (UC) efficiency, especially for neodymium (Nd3+)-sensitized UCNPs. Rational configuration design can spatially separate activators and sensitizers, achieving the evolution from single core to multilayer structures. However, optimizing multiphoton UC emission via configuration modulation, especially in the ultraviolet range, is yet to be fully investigated. In this work, thickness tuning of the sensitizing layer containing Nd3+ ions and the inert layer containing gadolinium ions at a fixed combined thickness of 5 nm in tetralayer UCNPs to exclude the size effect is reported for the first time. The optimal thickness of sensitizing and inert layers was determined to be 3 and 2 nm respectively, showing a new strategy of balancing sensitization and surface passivation to enhance 4-photon (360 nm) emission. Although 3-photon emission (475 nm) is mainly influenced by the overall size, its emission intensity remains similar in all the tetralayer UCNPs. Additionally, an 808 nm cross-linked hydrogel has been demonstrated as a potential near-infrared activated tissue sealant. Our results have uncovered the structural parameters for optimal ultraviolet UC emissions and elucidated the strategic importance of nano-configuration design to minimize the energy loss in the high-photon UC process.