Electrochemical Detection - Waterborne Pathogens: Detection Methods and Applications - page 159

electrochemical sensor measures this cellular response. Using cells as biore-
ceptors is particularly interesting because cells provide (1) a sensitivity to a
wide range of biochemical stimuli, (2) very low detection limits, and (3) a
functional assay for biochemical agents. Their major limitation is their need
for a specific well-controlled environment to function normally. Proteins
found within cells can also serve the purpose of bioreceptors. In particular,
biological cell membranes are the host of a great variety of molecules acting
as receptors in the interactions with the external environment. Being more
robust than antibodies due to their function, they are of special interest for
the development of novel biotechnological tools. 78 A receptor that is fabri-
cated and designed to mimic a bioreceptor (antibody, enzyme, cell, or nucleic
acid) is often termed a biomimetic receptor. There are several methods to
produce these receptors such as genetic engineering (e.g. aptamer), artificial
membrane fabrication, and molecular imprinting. Aptamers are similar to
nucleic acids in that they are ligands of deoxyribonucleic acids or ribonucleic
acids. They are specifically designed (using systematic evolution of ligands by
exponential enrichment) to bind a target protein. 79,80 Molecular imprinting
produces artificial recognition sites by molding a polymer around a molecule
which can be used as a template. 81,82 Recently, bacteriophages have been
employed as biorecognition elements for the identification of various patho-
genic microorganisms. They are viruses that bind to specific receptors on the
bacterial surface in order to inject their genetic material inside the bacteria. 83
6.8.2. Electrode material
Integrated electrochemical biosensors use mainly inorganic material as
semiconductors (doped silicon, silicon nanowire, CNT, boron-doped
diamond, etc. …), metals (gold, titanium, platinum, etc. …) or dielectrics
(oxide). Nanomaterials provide a new perspective for the development of
electrochemical biosensors. Nanoscale materials have been used to achieve
direct wiring of enzymes to electrode surfaces, to promote electrochemical
reactions, to impose nanobarcodes on biomaterials, and to amplify the signal
from biorecognition events. Currently new materials are being studied (i.e.
conducting-doped polymers, graphene, and composite materials).
These last years, conducting-doped polymers have been extensively
studied to provide flexible and cost-effective biocompatible electrodes
for electrochemical biosensing. Doped poly(3,4-ethylenedioxythiophene)
(PEDOT) have been micropatterned successfully to fabricate integrated
polymeric electrochemical biosensors by associating them with polymeric
substrate. For example, Kiilerich-Pedersen has made an impedimetric