Biomedical Engineering Reference
In-Depth Information
imprinted nanospheres with diameter of 120- 180 nm are obtained.
Among the MIP nanospheres the MIPs using combination of MAA and
MMA showed nanospheres with lowest mean diameter (120 nm) and the
highest selectivity factor (9.7). Moreover, release experiments showed the
controlled release of Nalidixic acid in longtime period.
In another work, Cu
2+
-mediated salbutamol-imprinted polymer
nanoparticles, synthesis via precipitation polymerization, were reported by
Alizadeh
et al.
, which later on mixed with graphite powder and n-eicosane
in order to fabricate a modii ed carbon paste electrode [80]. h is electrode
was then applied for indirect dif erential pulse voltammetry determination
of salbutamol. In the presence of Cu
2+
ions, the formed Cu
2+
-salbutamol
complex was adsorbed in to the pre-designed cavities of the MIP particles,
situated on the electrode surface. Since the electrochemical signal of sal-
butamol was intrinsically small, the oxidation peak of the participant Cu
2+
,
at er reduction step, was recorded and used as an indication of salbutamol
amount, adsorbed in the electrode. Dif erent variables inl uencing the sen-
sor performance were studied and the best conditions were chosen for the
determination purpose.
Folic acid has been used as a template to generate molecularly imprinted
polymers (MIPs), both thin i lms and nanoparticles [81]. Systematic stud-
ies on binding behavior include using two dif erent polymer systems,
namely methacrylates and acrylate-vinyl pyrrolidone copolymers. Both
yield sensor characteristics with lower limits of detection of 1-30 ppm with
QCM (quartz crystal microbalance), whereas the non-imprinted polymers
do not generate any signals. For methacrylate-based systems, switching
from thin i lms to MIP nanoparticles increases sensitivity by a factor of
3.0 and selectivity toward metabolites (leucovorin and anhydroleucovo-
rin) from broadband to specii c. In contrast to this, in poly vinyl pyrrol-
idone based materials going from thin i lms to MIP nanoparticles does not
increase sensitivity, but selectivity: thin i lms yield selectivity factors of 2-3
between folic acid and its metabolites, whereas nanoparticles do not show
any response toward the latter and thus can be regarded specii c. Hence,
not only the heterocyclic backbone, but also the carboxylic groups of the
folic acid molecule play fundamental role in detection. Vinyl pyrrolidone
thus is the more suitable monomer than methacrylic acid to ensure these
properties.
In another work, Tahir alizadeh
et al.
reported the synthesis of nanopar-
ticles of promethazine-imprinted polymers by the ultrasonic assisted sus-
pension polymerization in silicon oil [82]. h e MIP particles were then
embedded in a carbon paste (CP) electrode in order to prepare the MIP
(nano)-CP electrode. h is electrode showed higher response to analyte,
