Biomedical Engineering Reference
In-Depth Information
Figure 7.10
Examples of DNA detection by fluorescence in a DNA biochip. Fluorescent spots cor-
respond to a positive reaction, and can be treated by image processing.
the definition of a detection device. Optic methods by fluorescence are very widely
used. The principle is to attach a fluorescent bead to the immobilized target mol-
ecule and to implement a sensitive reception of the emitted light (Figure 7.10).
7.3 Biochemical Reactions
Biochemical reactions can be extremely complex. In the following, we will not go
into the details of these reactions, but only treat the reactions kinetics. The precise
chemical interactions leading to reaction is the domain of the biologists and chem-
ists. In biotechnology, we are only interested in the kinetics of the reaction to know
and improve its efficiency and reduce its duration.
7.3.1 Rate of Reaction
7.3.1.1 Definition
Consider a chemical reaction of the form
(7.1)
A nB mC D
+ ®
+
And note the molar concentration of a participant
J
at some instant by the sym-
bol [
J
]. The rate of consumption of a reactant at a given time is defined by -
d
[
R
]/
dt
,
where
R
is either
A
or
B
; this rate is a positive quantity (Figure 7.11). The rate of
formation of one of the products
C
or
D
—which we denote P—is defined by
d
[
P
]/
dt
and is also a positive quantity (Figure 7.12).
By considering the stoichiometry of reaction (7.1), we deduce the relations
d D
[
]
1
d C
[
]
d A
[
]
1 [
d B
]
(7.2)
=
= -
= -
d t
m d t
d t
n d t
The rate of reaction is uniquely defined by
1
1
(7.3)
v
=
v
=
v
=
v
=
v
D
C
A
B
m
n
