Enzymatic activity of Fe-grafted mesoporous silica nanoparticles: an insight into H2O2 and glucose detection

Abstract

Mesoporous silica nanoparticles (MSNs) have attracted a lot of notice as a platform in nanomaterials due to their specific properties such as large surface area, high pore size and volume, physical stability and uniform structures. The application of pure MSNs in various industries such as the petrochemical and pharmaceutical industries has been developed. The incorporation of metals into MSNs can increase the catalytic activity of MSNs due to their specific properties such as pore size and volume. Modification of MSNs by iron atoms (Fe-MSN) was studied in this research. The Fe-MSN was prepared using a sol–gel method. Here a comprehensive study was conducted on its enzyme mimicking and biocatalytic activities toward the oxidase, peroxidase and catalase enzymes. Hence, the relevant biocatalytic parameters were obtained through the reliable enzyme kinetic models. The results showed that Fe-MSN has high catalytic activity for decomposition of hydrogen peroxide (catalase activity) and for oxidation of aromatic hydrogen donors such as 3,3′,5,5′-tetramethylbenzidine (TMB). This activity can be carried out in the presence of oxygen as an oxidant (oxidase activity) and/or in the presence of a peroxide substrate, e.g. H₂O₂ (peroxidase activity) to produce the blue-colored product. Consequently, a colorimetric method was developed to determine H₂O₂ by Fe-MSN indicating a reasonable limit of detection (LOD) of 1.2 μM (3σ/slope) and a linear range over 7.2–100 μM. When Fe-MSN was coupled with glucose oxidase (a bienzymatic sequential detection system) glucose as a substrate can be detected at ≤1.2 μM over an experimental linear range of 4.1–100 μM.