Metallic Nanoparticles for Biomedical Applications
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is illustrated in the third section including solid-state, gas-phase, liquid-phase, biological, microfluidic-based and other techniques. Advantages, limitations and importance of each method is illustrated with key examples describing the controlled
synthesis. Finally, it summarizes the synthesis method and discusses prospects.
1.1 Nanoparticles and Its Properties
NPs are the entities whose size ranges from 10 to 1000 nm. Due to its small size,
it gives rise to a various exciting phenomenon which is not shown by their bulk
counterpart [5]. As the size decreases, surface area to volume ratio increases exponentially and hence, make its surface and surroundings more reactive itself [6].
Apart from size, shape, and other physicochemical properties of NPs enables it
to use in various fields such as biomedical and environmental to use it in catalysis,
sensing, imaging, drug delivery, energy production, storage and water treatment [7–
9]. The physical properties include size and size distribution, shape, specific surface
area, aspect ratio, agglomeration, surface morphology, structure, and solubility. The
chemical properties cover chemical composition, phase identity, surface chemistry,
and hydrophilicity. The important physicochemical properties include large surface
area, electronic and optic properties, magnetic properties, mechanical properties, and
thermal properties. Optical and electronic properties are closely related. Noble MNPs
show size-dependent optical properties and exhibit a strong UV-Vis absorption spectrum. The excitation band is due to the phenomenon of localized surface Plasmon
resonance (LSPR) of conduction electrons of metals, which will discuss later. It has
been found that the maximum wavelength of the absorption spectrum depends on
the size of the NPs. Magnetic properties of NPs are originating from the unequal
electronic distribution. It has been observed that when the size of the synthesized NP
is less than the critical value, magnetic properties dominate. The mechanical properties of NPs have to be studied in detail based on their applications. NP solutions
are expected to show thermal properties, because it usually synthesizes in solvents
such as water, oil or ethylene glycols (EG). Also, higher surface area favours the heat
transfer along the surface of particle. It has been reported that nanofluids containing
copper oxide or aluminium oxide NPs in water or ethylene showed advanced thermal
conductivity [5].
1.2 Theories on the Formation of Nanoparticles
The type of synthesis approach adopted dictates the size, shape, morphology, and
uniformity of NPs, which in turn dictates the novel properties of NPs. Thus, a
controllable synthesis and processing become the basis of nanotechnology to realize
potential applications of NPs.
31
is illustrated in the third section including solid-state, gas-phase, liquid-phase, biological, microfluidic-based and other techniques. Advantages, limitations and importance of each method is illustrated with key examples describing the controlled
synthesis. Finally, it summarizes the synthesis method and discusses prospects.
1.1 Nanoparticles and Its Properties
NPs are the entities whose size ranges from 10 to 1000 nm. Due to its small size,
it gives rise to a various exciting phenomenon which is not shown by their bulk
counterpart [5]. As the size decreases, surface area to volume ratio increases exponentially and hence, make its surface and surroundings more reactive itself [6].
Apart from size, shape, and other physicochemical properties of NPs enables it
to use in various fields such as biomedical and environmental to use it in catalysis,
sensing, imaging, drug delivery, energy production, storage and water treatment [7–
9]. The physical properties include size and size distribution, shape, specific surface
area, aspect ratio, agglomeration, surface morphology, structure, and solubility. The
chemical properties cover chemical composition, phase identity, surface chemistry,
and hydrophilicity. The important physicochemical properties include large surface
area, electronic and optic properties, magnetic properties, mechanical properties, and
thermal properties. Optical and electronic properties are closely related. Noble MNPs
show size-dependent optical properties and exhibit a strong UV-Vis absorption spectrum. The excitation band is due to the phenomenon of localized surface Plasmon
resonance (LSPR) of conduction electrons of metals, which will discuss later. It has
been found that the maximum wavelength of the absorption spectrum depends on
the size of the NPs. Magnetic properties of NPs are originating from the unequal
electronic distribution. It has been observed that when the size of the synthesized NP
is less than the critical value, magnetic properties dominate. The mechanical properties of NPs have to be studied in detail based on their applications. NP solutions
are expected to show thermal properties, because it usually synthesizes in solvents
such as water, oil or ethylene glycols (EG). Also, higher surface area favours the heat
transfer along the surface of particle. It has been reported that nanofluids containing
copper oxide or aluminium oxide NPs in water or ethylene showed advanced thermal
conductivity [5].
1.2 Theories on the Formation of Nanoparticles
The type of synthesis approach adopted dictates the size, shape, morphology, and
uniformity of NPs, which in turn dictates the novel properties of NPs. Thus, a
controllable synthesis and processing become the basis of nanotechnology to realize
potential applications of NPs.