Biomedical Engineering Reference
In-Depth Information
maximum at about 420 nm, the Au colloids show a maximum at about
550 nm.
Now with advances in science and technology, the morphology of this
material, which contains metallic nanoparticles, has been understood [17].
Nanoadsorbents of er signii cant improvements over conventional adsor-
bents with their extremely high specii c surface area, short interparticle dif-
fusion distance, pore size and surface chemistry. High specii c surface area is
mainly responsible for their high adsorption capacity. Furthermore, the high
surface energy and size-dependent surface structure at the nanoscale may
create highly active adsorption sites [18], resulting in higher surface-area-
normalized adsorption capacity. Other dif erent types of polymers like
polyesters, polyethene, nylon, and PVC are lightweight materials and are
easily mixed to form new materials. Inorganic carbon materials like graphite,
fullerenes, carbon nanotubes and diamondoids greatly contribute to carbon-
reinforced nanomaterials. Biologically-based materials such as carbohy-
drates, proteins, lipids and nucleotides are also showing great value. Proteins
are nontoxic and can be easily functionalized. So our main objective is to
include comparative research on the ei cacy of newly designed nanosensor
and available material for visual detection of toxic metal ions in water media.
Here we have focused on designing l uorescent nanosensors (Au@citrate,
Ag@citrate, Au nanorods, etc.) for toxic metal ions detection in water.
10.3 Dif erent Fabrication Methods of Nanoparticles
Nanoparticles can be synthesized by physical, chemical or biological meth-
ods. Synthesis of nanomaterials can be divided into two categories, viz.,
top-down and bottom-up approach [35]. In the “top-down” approach,
macroscopic particles can be reduced to nanosize by removal of material.
h is approach involves milling, machining and lithography techniques. On
the other hand the “bottom-up” approach involves aggregation of atoms to
form particles of dei nite size, shape or structure. Dif erent “top-down” and
“bottom-up” fabrication methods of nanoparticles are shown in Figure 10.2.
In almost all the applications of nanostructures, fabrication represents
one of the most signii cant challenges to their realization. h ere are advan-
tages as well as disadvantages of using any fabrication method. h ere are
a variety of materials prepared by the above-discussed methods which
are composed of both metallic and non-metallic elements such as Al2O3,
TiO2, SiO2, TiN, SiC, Ag, Au, Pt, Pd, Ni NPs, etc.
Some analytical methods have been developed to make ratiometric
l uorescent sensors for metals [36]. Table 10.1 shows the toxicity study of
