What is it about?

Atomic force microscopy (AFM) is becoming a very impor- tant tool in the biological ¢eld. With this technique the cells are observed alive and do not require ¢xing methods com- monly used in scanning electron microscopy [1,2]. AFM works as a pro¢lometer works: by moving a com- mercial microfabricated tip across the sample. This tip is held at the end of a thin, £exible, gold cantilever (100 ‡m long, about the width of a hair) [3] (see Scheme 1B). Recently, an interesting biodetector was developed by im- mobilizing enzymes on a gold surface (thermo-optical detec- tor, Scheme 1A) [4^10]. This equipment is based on the heat evolved from an enzymatic reaction which provokes de£ec- tions of a laser beam and this result is registered as a graph [6^10]. Since AFM has almost the same parts as the thermo- optical detector (laser beam, lens and photodiode) (Scheme 1B), if an enzyme (glucose oxidase) was immobilized on a cantilever, it is hoped that the temperature gradient generated by reaction heat (between the enzyme and its substrate) could induce a de£ection of the cantilever, transforming the AFM into an apparatus that could reveal the presence of speci¢c biomolecules being absorbed by living cells, together with the image of the cells. These assumptions were demonstrated to be consistent with the experimental protocol and the goal of this paper is to describe a method of constructing nanobiosensors by immobilizing enzymes (glucose oxidase or hexoki- nase) onto the cantilever in order to detect biological molecules. Saccharomyces cerevisiae was used for these experiments because of its importance in the food and pharmaceutical industries

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Why is it important?

The importance lies in the manufacture of probes derivatized with enzymes and other biological materials to perform tests in clinical analysis.

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This page is a summary of: Detection of the absorption of glucose molecules by living cells using atomic force microscopy, FEBS Letters, June 2000, Wiley, DOI: 10.1016/s0014-5793(00)01622-7.
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