Investigation into immobilisation of lactate oxidase to improve stability

Lactate oxidase (LOx) is an unstable enzyme. In this work, a variety of immobilisation techniques are investigated in an effort to improve the long-term stability of the enzyme. These include covalent linkage to two membrane types, encapsulation in a BSA gel and four different sol–gel matrices. The enzyme glucose oxidase (GOx) was also immobilised in the same sol–gel matrices. The methods were assessed for both activity and stability of the enzyme and the mechanical rigidity of the matrix. The BSA and sol–gels both formed physically robust enzyme layers. The enzyme retained its activity in the BSA gel for 20 days. Activity of the enzyme was much higher in the sol–gel matrices and remained stable for at least 55 days. Sol–gel processing conditions were also investigated.