Biomedical Engineering Reference
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O
1) (CH
2
O)
n
, DMF
O
NH
3
Cl
O
O
N
O
N
O
HOOC
NHBoc
O
N
O
O
O
N
OH
O
120 °C, 3 days
OH
O
DIEA, DMF
2) HCl in dioxane
1
7
O
O
O
O
N
H
N
S
N
O
O
O
O
GRGDSP-Cys
O
O
N
H
N
GRGDSP-C
OH
N
Water
O
O
OH
9
IKVAV-C
O
8
O
Water
O
O
H
N
S
N
O
O
IKVAV-Cys
OH
10
Scheme 6.3
Synthesis of peptide-CNT conjugates.
The electrophysiological responses of rat dissociated hippocampal
neurons in culture incubated with the two peptide-nanotube conjugates
were then studied. The spontaneous activity of single neurons in voltage
clamp coniguration was recorded. The neuronal activity was detected as
inward currents, corresponding to synaptic events, of variable amplitude.
These events represent a mixed population of inhibitory and excitatory
spontaneous postsynaptic currents. Some neuronal passive properties were
then examined and measured under voltage clamp. They are indicative of
neuronal function such as membrane capacitance and input resistance. By
quantifying peak amplitude of inward and outward currents to the membrane
capacitance value of each recorded cell, inward and outward current
densities were obtained. The values were found to be similar in the case of
the RGD-containing peptide conjugated to MWNTs when compared with the
peptide alone. Thus, the incubation of neurons in the presence of MWNTs
functionalised with peptides did not modify neuronal spontaneous activity.
In summary, these data showed that peptide-nanotube conjugates
incubated with neuronal cells did not alter the neuronal morphology, viability
and basic functions of the neurons. These results are different from those
obtained by Haddon and coworkers in which PEG-SWNTs were found to
inhibit membrane endocytosis in stimulated neurons, which should lead to
a progressive decrease of frequency in spontaneous PSCs, as will be detailed
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