The effect of functionalization of mesoporous silica nanoparticles on the interaction and stability of confined enzyme

Immobilization of enzymes into the mesoporous nanomaterials results in formation of more stable and even more active versions of biocatalysts. The effect of surface functionalization of mesoporous silica nanoparticles (MSNs) on its adsorption characteristics and stability of superoxide dismutase (SOD) was investigated. For this purpose, non-functionalized (KIT-6) and aminopropyl-functionalized cubic Ia3d mesoporous silica ([n-PrNH2-KIT-6]) nanoparticles with 3-dimensional pores were used as supports. It was observed that the amount of enzyme adsorbed on/within MSNs is dependent on the initial enzyme concentration for both KIT-6 and [n-PrNH2-KIT-6] mesoporous silicas. However a stronger interaction between SOD and [n-PrNH2-KIT-6] was observed relative to KIT-6. Increasing temperature favors a larger amount of SOD immobilization into KIT-6, while it was negligible for [n-PrNH2-KIT-6]. Immobilized SOD was more stable against urea and thermal denaturation relative to free enzyme and this improvement of stability was more pronounced for SOD into the [n-PrNH2-KIT-6] than KIT-6. These results may be useful in determining the mechanism(s) of protein immobilization and stabilization into the solid supports.

► SOD immobilized onto the KIT-6 and [n-PrNH2-KIT-6].
► stronger interaction between SOD and [n-PrNH2-KIT-6] relative to KIT-6.
► SOD–[n-PrNH2-KIT-6] is more stable than SOD-KIT-6 against urea.
► SOD–[n-PrNH2-KIT-6] is more stable than SOD-KIT-6 against temperature.