Biomedical Engineering Reference
In-Depth Information
i lter into the soils and contaminates potable water sources. h is is why
these chemicals af ect the food chain producing high damage in human's
health [105-107]. High-level exposure to OPs results in the inhibition
of the acetylcholinesterase (AChE) activity, which may cause respiratory
paralysis and death [48].
In Chemistry Research, it is important to establish precise and exact
methods for detection and quantii cation of Pesticides, HPLC is consid-
ered the best technique for this purpose, however, new methodologies
based on nanotechnology allow precise and exact analysis of dif erent
pesticides by means of electrochemical techniques such as amperometry,
chronoamperometry, voltammetry cyclic voltammetric stripping (SV) and
square wave voltammetry (SWV).
Trends in pesticide analysis focus on the development of composite
biosensors based on nanomaterials and enzymes as recognition agents.
Generally, methods based on electrochemical biosensors do not depend
only on selecting a suitable enzyme to ensure pesticide's detection, but on
the study of dif erent parameters such as: the optimum amount of nano-
material, of enzyme, and the dispersant agent which prevents the forma-
tion of agglomerates. Other parameters important in detection are: the
optimal pH related to the enzyme activity and the instrumental parameters
which depend on the electrochemical technique used (applied potential
(E
ap
), time, etc).
Detection of OPs is essential to protect water resources and food, as well
as for monitoring detoxii cation processes. Constructing biosensors can be a
challenge when immobilizing the enzyme on the electrode´s surface due to
the loose of enzyme's activity; however, the use of nanomaterials promotes
the conservation of this activity. h e most commonly used enzymes for the
construction of biosensors for OP analysis are: choline oxidase (ChO) horse-
radish peroxidase (HRP), tyrosinase (Tyr), organophosphorus hydrolase
(OPH) and acetyl-cholinesterase (AChE) [108]. Among all of these enzymes,
stands the OPH, which converts OP compounds to p-nitrophenol; the oxi-
dation is carried out at the electrode's surface where the enzyme catalyzes the
chemical reaction enabling the electrochemical detection.
GR is used due to its interactions with enzymes type π-stacking which
induce non-specii c bonds. h ese bonds are also produced by electro-
static interactions GR-enzyme, which generate a better adsorption of the
enzyme [109].
In general, detection of a substance at high potentials means poor selec-
tivity for the analytical method. GR, with excellent electrocatalytic prop-
erties, improves the analytical response, including the detection limit.
However, direct use of GR sheets is not suitable for sensor's construction
due to its low solubility, instead, GR derivatives are used, especially by
