Supercritical Fluid-Assisted Fabrication of Manganese (III) Oxide Hollow Nanozymes Mediated by Polymer Nanoreactors for Efficient Glucose Sensing Characteristics

Despite their inherent efficacy in significantly accelerating the rate of chemical reactions in biological processes, the applicability of natural enzymes is often hindered because of their intrinsic limitations such as high sensitivity, poor operational stability, and relatively high cost for purification as well as preparation. Thus, the fabrication of catalytically active nanomaterials as artificial enzymes (nanozymes) has become a newly burgeoning area of research in bionic chemistry, aiming in designing functional nanomaterials that mimic various inherent properties of natural enzymes. To address these issues, we present the supercritical fluid (SCF)-assisted fabrication of discrete, monodisperse, and uniform-sized manganese (III) oxide (Mn₂O₃)-based hollow containers as high-efficiency nanozymes for glucose sensing characteristics. Initially, the core-shell nanoreactors based on polyvinylpyrrolidone (PVP)-encapsulated manganese (III) acetylacetonate (Mn(acac)₃) as precursors are fabricated using the SCF technology and subsequent calcination resulted in the Mn₂O₃ hollow nanoparticles (MHNs). This eco-friendly approach has resulted in the PVP-coated Mn(acac)₃ nanoreactors with an average diameter of 220 nm and subsequent calcined hollow products are about one-fifth to that of the precursor. Such MHNs conveniently catalyzed 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H₂O₂) as a prominent peroxidase mimic, resulting in the oxidation products (TMB*⁺) at a specific absorption (UV-vis) maxima of 652 nm. Following typical Michaelis-Menten theory, this approach is further utilized to develop visual nonenzymatic sensing of glucose in a linear range of 0.1-1 mM at a detection limit of 2.31 μM. Collectively, this reliable as well as a cost-effective system with high precision potentially allows rapid detection of analytes, providing a convenient way for its utilization in diverse fields.