Biomedical Engineering Reference
In-Depth Information
In 2010 Zhou
et al
. reported the construction of a biosensor consisting
of a composite with multilayers of GR and CS along with the microper-
oxidase 11 (MP11). h is electrode of ers advantages like a direct electron
transference of the MP11, which maintains a high bioelectrocatalytic
activity in the O
2
y H
2
O
2
reduction. h is biosensor can quantify con-
centrations of H
2
O
2
ranging 2.5 to 135μM with a LOD of 2μM. Due to
the characteristics of this biosensor, it is considered of third generation
[132].
Depending on the biosensor's composition (Figure 5.9) [133], LOD can
be very low (Table 5.4) so even H
2
O
2
traces can be detected. Song
et al
.
[134] reported a biosensor based on the assembly of layers of molybde-
numdisuli de-graphene (MoS
2
-Gr) and horseradish peroxidase (HRP),
the formation of this novel nanomaterial is based on the electrostatic inter-
actions between dif erent components allowing a LOD of 0.04 μM, which
makes this attractive for the analysis of H
2
O
2
in the environment.
Up to date, GR use in combination with other nanomaterials for the
construction of biosensors, even non-enzymatic, has improved the detec-
tion and quantii cation of H
2
O
2
with LOD in the range of picomolar con-
centrations [135, 136].
Table 5.4 Shows some of the coni gurations based on GR, where ultra-
sensitive responses and low detection limits can be observed for H
2
O
2
.
5.2.4.2 Microorganisms.
In the last decades, development of biosensors has been a very used strategy
for the detection of microorganisms, so many methods have been reported
for its determination and monitoring [141-143]. In the last years, the use
of nanomaterial [144, 145] like gold nanoparticules [146] quantum dots,
magnetic nanoparticules [147] and carbon nanotubes [148] have allowed
the signal amplii cation in electrochemical techniques. GR emerges as an
interesting material with great potential for applications in bionanotech-
nology, including areas regarding sensors and biomolecules[149-156]; all
of this due to its great surface area and low cost.
Among the microorganisms studied with GR based biosensors are bac-
teria like
Escherichia coli (E. coli)
, this is a bacteria with a bacillus form
(bar) (Figure 5.10) that can be found in the human intestine. Some strains
of
E. coli
present in contaminated food can cause severe infection of the
urinary tract (IUT). It is estimated that E. coli causes about 90% of the
infections [149]. h is justii es the importance of developing a low cost sen-
sor for the detection of this bacteria.
