Dual-Function Hierarchical Bimodal Mesoporous Silica Nanomaterials for Exceptional Sevoflurane Capture and Real-Time Sensing

In this study, we investigated the ability of hierarchical bimodal mesoporous silica nanomaterials (UVM-7 type), composed of aggregated mesoporous primary particles, to absorb anesthetic gases, particularly sevoflurane. We compared their adsorption and desorption capacities with those of microporous carbons in commercial cartridges designed to capture anesthetic gases, such as CONTRAfluran and FlurAbsorb. To analyze the importance of porosity type, we also included Stöber-type unimodal mesoporous silicas and other non-porous siliceous supports in the study. Pure UVM-7 silica can capture up to 2.52 mL of gas per gram. This is much higher than for commercial carbons, which range from 0.2 to 0.34 mL/g. In addition, gas desorption occurs more efficiently than with carbons. We selected a range of materials with distinctly different pore systems to analyze the relationship between pore type and adsorption properties. To achieve this objective, a range of techniques was used to characterize the materials and reveal their structural architecture. Additionally, the adsorption and desorption processes were modeled using five models, which helped elucidate the parameters that govern their kinetics. The sevoflurane capture capacity of iron-functionalized UVM-7 silicas has also been evaluated. These materials preserve the porous architecture of the original silica and contain nanodomains of hematite within their mesopore walls, imparting a brownish-red color. Color attenuation upon sevoflurane adsorption provides a visible optical response, likely arising from changes in light scattering within the hierarchical particle structure, including possible Mie-type contributions.