Biomedical Engineering Reference
In-Depth Information
l uorescence. Eliminating further treatment or modii cation, this method
simplii es and shortens the experimental process.
11.2.1.6 Nanobeads
Rajabi
et al.
reported a voltammetric sensor for selective recognition and
sensitive determination of mercury ions using glassy carbon electrode (GCE)
modii ed with a novel ion imprinted polymeric nanobeads (IIP) and multi-
wall carbon nanotubes (MWCNTs) [51]. h e ion-imprinted polymers were
prepared by dissolving the certain amount of mercury chloride and 5, 10,
15, 20-tetrakis (3-hydroxyphenyl) porphyrin, in the presence of methacrylic
acid and ethyleneglycol-dimethacrylate, using 2,2-azobisisobutyronitrile as
initiator. h e dif erential pulse anodic stripping voltammetric technique was
employed to investigate the performance of the GC-IIP-MWCNTs modi-
i ed electrode for determination of hazardous mercury ions. h e designed
modii ed electrode was shown a linear response in the range of 1×10
-8
-
7.0×10
-4
M of Hg
2+
ion with a detection limit of 5.0 nM. It was found that
the peak currents of the modii ed electrode for Hg
2+
ions were at maximum
value in acetate buf er. h e pre-concentration potential and accumulation
time were optimized to be -1.0 V and 100 s, respectively.
11.2.1.7 Nanowires/Fibers
A nanowire is a nanostructure, with the diameter of the order of a nano-
meter (10−9 meters). Alternatively, nanowires can be dei ned as structures
that have a thickness or diameter constrained to tens of nanometers or less
and an unconstrained length. At these scales, quantum mechanical ef ects
are important which coined the term “quantum wires”. Many dif erent
types of nanowires exist, including metallic (e.g., Ni, Pt, Au), semiconduct-
ing (e.g., Si, InP, GaN, etc.), and insulating (e.g., SiO
2
, TiO
2
).
First of all, Li
et al.
reported a convenient imprinting method for the
preparation of magnetic molecularly imprinted nanowires within the
pores of nanoporous alumina membrane in the year 2006 [52]. h e tem-
plate molecule (theophylline) was immobilized on the pore walls of a
nanoporous alumina membrane. h e nanopores were then i lled with a
pre-polymerization mixture containing the superparamagnetic MnFe
2
O
4
nanocrystallites. At er polymerization, the alumina membrane was subse-
quently removed by chemical dissolution, leaving behind magnetic poly-
mer nanowires that contain theophylline-binding sites uniquely residing
at the surface and have a saturated magnetization (MS) of 1.97 emu/g.
h e resulting magnetic imprinted polymer nanowires were capable of
binding theophylline more strongly than the non-imprinted nanowires.
