Enzyme immobilization and direct electrochemistry based on a new matrix of phospholipid-monolayer-functionalized...

A new nanocomposite material for enzyme immobilization and subsequent direct electrochemistry and electrocatalysis was developed by using 1,2-dimyristoyl-sn-glycero-3-phospho-(1-rac-glycerol)-phospholipid-monolayer-membrane-modified graphene (DMPG-G). Microperoxidase-11 (MP11) was chosen as a model enzyme to investigate the composite system. Owing to the improved conductivity and biocompatible microenvironment, MP11 that was immobilized in the matrix of the DMPG-G nanocomposite (DMPG-G-MP11) effectively retained its native structure and bioactivity. DMPG-G-MP11-modified glassy carbon electrode (DMPG-G-MP11/GCE) exhibited a pair of well-defined quasi-reversible redox peaks of MP11 and showed high electrocatalytic activity towards hydrogen peroxide (H(2)O(2)). The linear response of the developed biosensor for the determination of H(2)O(2) ranged from 2.0×10(-6) to 4.5×10(-4)  M with a detection limit of 7.2×10(-7)  M. This biosensor exhibited high reproducibility and long-term storage stability. The promising features of this biosensor indicate that these lipid-graphene nanocomposites are ideal candidate materials for the direct electrochemistry of redox proteins and that they could serve as a versatile platform for the construction of a third-generation biosensor.