Step-Up Synthesis of Periodic Mesoporous Organosilicas with a Tyrosine Framework and Performance in Horseradish Peroxidase Immobilization

Graphical Tyr'd out : Novel periodic mesoporous organosilicas with a tyrosine framework (Tyr-PMOs) are constructed. Tyrosine units are incorporated into the framework at the same time as phenolic hydroxy groups as binding centers are introduced within the channels. A long storage time and conventional stability are found for the Tyr-PMOs after the immobilization of horseradish peroxidase (HRP). New amino-acid-bridged periodic mesoporous organosilicas (PMOs) were constructed by hydrolysis and condensation reactions under acid conditions in the presence of a template. The tyrosine bissilylated organic precursor (TBOS) was first prepared through a multistep reaction by using tyrosine (a natural amino acid) as the starting material. PMOs with the tyrosine framework (Tyr-PMOs) were constructed by simultaneously using TBOS and tetraethoxysilane as complex silicon sources in the condensation process. All the Tyr-PMOs materials were characterized by XRD, FTIR spectroscopy, N 2 adsorption–desorption, TEM, SEM, and solid-state 29 Si NMR spectroscopy to confirm the structure. The horseradish peroxidase (HRP) enzyme was first immobilized on these new Tyr-PMOs materials. Optimal conditions for enzyme adsorption included a temperature of 40 °C, a time of 8 h, and a pH value of 7. Furthermore, the novel Tyr-PMOs materials could store HRP for approximately 40 days and maintained the enzymatic activity, and the Tyr-PMOs–10 % HRP with the best immobilization effect could be reused at least eight times.