Methods: We employed Al-MCM-41 as a catalyst support and immobilized Fe-Histidine and Mn-Histidine complex on Al-MCM-41. The characterization of Fe-Histidine/Al-MCM-41 and Mn-Histidine/Al-MCM-41 was performed using inductively coupled plasma atomic emission spectrometry, an elemental analyzer, thermogravimetric analysis, X-ray powder diffraction, and N2 adsorption-desorption isotherms. Finally, the effectiveness of tooth bleaching by H2O2 using Fe-Histidine/Al-MCM-41 and Mn-Histidine/Al-MCM-41 as catalysts was evaluated in test tubes and in an extracted tooth model.
Results: Mn-Histidine/Al-MCM-41 and Fe-Histidine/Al-MCM-41 exhibited great surface area and nano-pore size which could contribute to the adsorption of transition metal ions. Both catalysts improved the oxidation efficiency of Orange II by H2O2.
Conclusion: We have demonstrated successful immobilization of organometallic complexes on Al-MCM-41 to form Mn-Histidine/Al-MCM-41 and Fe-Histidine/Al-MCM-41 as catalysts toward the H2O2 decomposition to efficiently produce the .OH and .HO2 radicals for tooth bleaching.