Fully reversible biosensors for glucose monitoring based on solid polyvinylchloride (PVC) films where the enzyme glucose oxidase (GOx) was incorporated together with 2-phenyl-4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadec yl)benzylidene]-5-oxazolone (CPO-1), 2-(3,5-dinitrophenyl)-4-[4-(1,4,7,10-tetra oxa-13-azacyclopentadecyl)benzylidene]-5-oxazolone (CPO-2), 2-(4-nitrophenyl) -4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadecyl)benzylidene]-5-oxazolone (CPO-3) and 2-(4-tolyl)-4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadecyl)benzylidene]-5-oxazolone (CPO-4) derivatives have been developed. The limit of detection (LOD) values for glucose were found to be 1.47 Â 10 25 M, 2.01 Â 10 25 M, 0.89 Â 10 25 M, and 0.12 Â 10 25 M for CPO-1, CPO-2, CPO-3, and CPO-4, respectively (n ¼ 7). Sensor films were found to have excellent photostability.