Glucose detection based on pH-sensitive liposomes

PH-sensitive liposomes were employed to amplify the detection of glucose. Glucose oxidase (GOx) covalently immobilized on magnetic particles and pH-sensitive liposomes encapsulating ferricyanide were added to a cyclic voltammeter cell solution in which glucose was distributed. The conversion of glucose into gluconic acid appeared to decrease the pH, which reduced the electrostatic repulsion between the headgroups of weakly acidic 1,2-dipalmitoyl-sn-glycero-3-succinate. The reduction destabilized the liposomes, which released the potassium ferricyanide encapsulated inside them. The effects of the glucose concentration and pH value were investigated. It was necessary to add more than 10 µL of 0.5 μg/mL glucose solution to the 5 mL cyclic voltammeter cell solution to observe a response. The activity of GOx was reversible with respect to the pH change between 7 and 5. The sensitivity of this detection was almost identical to that of comparable techniques such as the use of a field-effect transistor. Therefore, the methodology developed in this study is feasible as a portable and ultrasensitive method.