Preparation and application of graphene oxide nanocomposites loaded with enzymes and liposomes

The present studies explored the possibility of immobilizing phosphocholine (PC) liposomes on the surface of graphene oxide (GO) which was pre-adsorbed with two kinds of enzymes, horseradish peroxidase and glucose oxidase. The transmission electron microscope images showed that the PC liposomes adsorbed onto the GO surface kept integrity. By using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-encapsulated liposomes, a one-step colorimetric assay for glucose was developed. In the presence of glucose, the GO nanocomposites catalyzed the cascade enzymatic reaction producing colorimetric signals directly. Under the optimal conditions, the GO nanocomposites produced linearly increased colorimetric signal with increased concentrations of glucose ranging from 50 to 500 µM. The detection limit was 33 µM. The GO nanocomposites also exhibited good selectivity for the detection of glucose and were able to detect glucose in human serum. Graphical abstract