Encapsulation and reactivity of the enzyme oxalate oxidase in a sol-gel derived glass

The enzymes oxalate oxidase and peroxidase are encapsulated in stable, optically transparent, porous silica glass matrices synthesized under mild conditions using novel sol-gel synthetic techniques. The large enzymes are immobilized, but smaller molecules such as oxalate ions pass readily through the porous glass. Upon exposure to oxalate solutions, a colored glass is formed whose absorption spectrum and changes of absorbance with time are measured. The sensitivity of the response and the time-dependence of the response are discussed.