This study presents the synthesis and characterization of core-shell nanostructures of Mn₂O₃@SiO₂, Mn₂O₃@amino-functionalized silica, Mn₂O₃@vinyl-functionalized silica, and Mn₂O₃@allyl-functionalized silica. The nanostructures were synthesized using the hydrolysis of organosilane precursors over Mn₂O₃ nanoparticles dispersed in Tergitol and cyclohexane solutions. This method improves upon the commonly used post-grafting or co-condensation methods by ensuring a high density of functional groups on the core-shell nanostructures. The high density of functional groups is beneficial for immobilizing biomolecules and drugs, as well as for the extraction of trace elements. Characterization techniques such as TEM, IR, and zeta potential studies were employed to confirm the successful synthesis and functionalization of the nanostructures. The zeta potential studies showed that the hydrolysis of organosilane precursors resulted in a higher number of functional groups compared to the post-grafting method. The amino-functionalized core-shell nanostructures were used to immobilize glucose and L-methionine, demonstrating their potential for biological applications. The methodology is applicable to the synthesis of core-shell nanostructures with high-density functional groups, which can be used for various analytical purposes.This study presents the synthesis and characterization of core-shell nanostructures of Mn₂O₃@SiO₂, Mn₂O₃@amino-functionalized silica, Mn₂O₃@vinyl-functionalized silica, and Mn₂O₃@allyl-functionalized silica. The nanostructures were synthesized using the hydrolysis of organosilane precursors over Mn₂O₃ nanoparticles dispersed in Tergitol and cyclohexane solutions. This method improves upon the commonly used post-grafting or co-condensation methods by ensuring a high density of functional groups on the core-shell nanostructures. The high density of functional groups is beneficial for immobilizing biomolecules and drugs, as well as for the extraction of trace elements. Characterization techniques such as TEM, IR, and zeta potential studies were employed to confirm the successful synthesis and functionalization of the nanostructures. The zeta potential studies showed that the hydrolysis of organosilane precursors resulted in a higher number of functional groups compared to the post-grafting method. The amino-functionalized core-shell nanostructures were used to immobilize glucose and L-methionine, demonstrating their potential for biological applications. The methodology is applicable to the synthesis of core-shell nanostructures with high-density functional groups, which can be used for various analytical purposes.