Detection of the absorption of glucose molecules by living cells using atomic force microscopy

A very small electrode (nanobiosensor) was constructed by immobilizing enzyme (glucose oxidase or hexokinase) on the surface of the cantilever of the atomic force microscope in order to detect the absorption of glucose molecules by living cells. If glucose is present, the nanobiosensor deflects, probably due to the reaction heat evolved in the process. Nanobiosensors built with inactivated enzyme or cantilevers without immobilized enzyme were not capable of producing this type of signal (deflection). This technique will be very useful in detecting the passage of specific molecules through a cell wall (or a cell membrane for other types of cells).