Enzymatic Sol–Gel Biosensors

We review the recent progress in the use of the sol–gel technology to develop enzymatic biosensors. We have emphasized how the sol–gel matrix properties turn them as ideal hosts to encapsulate enzymes that can act as the biorecognition elements of the biosensor device. However, at the same time, we have stressed the strong requirements imposed on the enzyme-doped sol–gel preparation in order to obtain an effective device operational over time. Thus, we explain how the sol–gel preparation conditions and properties have to be tuned in order to achieve a reliable biosensor. In this sense, several approaches and strategies to meet these requirements as well as to improve the biosensor performance are described. As the literature on these topics is indeed numerous, we have not intended to perform an exhaustive revision but rather to review the most important aspects of the subject providing at the same time with representative examples selected from the literature. In any case, in the text are referenced interesting reviews and papers that can be useful to complement this work because they use either points of view or literature works different from those employed by us.