Co-intercalation of myoglobin and Eu3+ ions into the gallery of layered titanate: Preparation, structures as well as enzymatic and photoluminescent properties

Myoglobin (Mb) and Eu3+ ions were co-intercalated into the galleries of layered titanate H0.7Ti1.825□0.175O4 · H2O (□ = vacancy) by the exfoliation assembly method. The structure, composition and morphology of the Mb,Eu3+/titanate composites were characterized by many techniques, such as XRD, HRTEM, ICP-AES, UV–vis spectra and SEM. No structural change of the immobilized Mb could be observed based on the FT-IR and UV–vis spectra analyses. The activity studies show that the intercalated Mb retained enzymatic peroxidase activity. The Mb,Eu3+/titanate composites with mass ratios (Mb: titanate) of 1.8 retained 53% initial rates of free Mb. Meanwhile, intensely red emission was exhibited in the PL spectra for the intercalated Eu3+ ions at room temperature, which may be due to the band gap excitation in the titanate nanosheets.