The Immobilization Of Enzyme And Stimuli-sensitive Release System Based On Mesoporous Silica Materials

Functional mesoporous silica materials show the better performance on enzymeimmobilization, electrochemical analysis, biosensor and stimulus-responsive drugdelivery. Mesoporous organosilicas with phenyl groups in the framework, mesoporoussilica film on the surface of the indium tin oxide (ITO) film and functionalmesoporous silica particle have been used as the supports for the immobilization ofenzyme and stimuli-sensitive release system in this dissertation.1. A series of mesoporous organosilicas with different phenyl group content havebeen synthesized for the immobilization of Heme proteins. A higher number of phenylgroups are conducive to immobilization of Heme proteins and improvement of theactivity of the immobilized enzymes. The amount of immobilized horseradishperoxidase (HRP), myoglobin (Mb) and hemoglobin (Hb) is35mg,51mg and44mg,respectively, with1g of mesoporous organosilica. In particular, the immobilizationefficiency of Mb can reach100%. A sensor utilizing HRP immobilized in mesoporousorganosilica is constructed on a glassy carbon electrode. In buffer solution (pH6.0),the modified electrode shows an electrochemical response towards catechol. 2. An electrochemical biosensor based on the immobilization of HRP onmesoporous silica on the surface of indium tin oxide (ITO) film is developedsuccessfully. The biosensor is designed for the quantitative analysis of phenoliccompounds. The cyclic voltammetry, with [Fe(CN)6]3-as probe, shows thatMSF@ITO electrode can be used as an electrode for electrochemical analysis. Theimmobilized horseradish peroxidase (HRP/MSF@ITO) biosensor is proved to besensitive to all studied phenolic compounds. The detection limits of the optimizedbiosensor for phenol, catechol, hydroquinone and resorcinol are0.12μM,0.08μM,0.24μM and0.004μM, respectively. The sensitivities are47nA μm-1,75nA μm-1,15nA μm-1and146nA μm-1, respectively.3. Enzyme and voltage stimuli are more biologically compatible in the field ofstimuli-responsive systems and release systems based on β-cyclodextrin (CD) andferrocene (Fc) have attracted much attention. Herein, mesoporous silica nanoparticles(MSNs) have been functionalized with the ferrocenyl moiety (Fc) which interactswith β-cyclodextrin (β-CD) to form an inclusion complex on the opening of the pores.The size of the inclusion complex results in a barrier to the opening of the pores.Based on these characteristics, MSNs with nanovalves have been developed as arelease system. The release system shows a clear response to Heme protein(horseradish peroxidase or hemoglobin) and H2O2, glucose oxidase (GOD) withhorseradish peroxidase (HRP) and glucose, or+1.5V based on an oxidation stimulusmechanism. Modulating the mount of enzyme or the discretion of the voltage makesthe release system a controlled one.