30
K. Illath et al.
1 Introduction
The history of nanoparticles (NPs) dates back to almost 4500 years ago; ancient
humans utilized natural asbestos nanofibers in developing ceramic matrices. Four
thousand years ago, Egyptians used ~5 nm diameter lead sulfide NPs for hair dye
treatment, synthesized from a chemical synthetic process. ‘Egyptian blue,’ a multifaceted mixture of cuprorivaite and silicon dioxide, is considered as the first synthetic
material prepared from nanometer-sized glass and quartz, used by Egyptians around
third century BC. Later in the thirteenth- and fourteenth-century BC, Egyptians
and Mesopotamians started synthesizing glass from metallic nanoparticles (MNPs).
During the Bronze age, surface plasmon excitation of cobalt nanoparticles (Co NPs)
has been utilized in colouring the surface of red glass. Co NPs were also used in Celtic
red enamels [1]. Another notable pioneering work in the MNPs era is the Lycurgus
cup, used back to fourth century AD. The cup can change its colour depends on
the location of the light source. Further analysis of this cup revealed that it consists
of minimal quantities of ~70 nm gold and silver crystals with an appropriate molar
ratio of 14:1, which results in its surprising characteristics [1, 2]. Later, gold and
silver nanoparticles (Au & Ag NPs) in appropriate ratios have been utilized in red
and yellow stained glass to decorate churches. Optical properties of Ag and copper
nanoparticles (Cu NPs) were employed in glazed ceramics by Mesopotamians. It
displays bright green and blue colours under particular specific radiation. Investigation revealed that ceramics has an outer double layer of Ag NPs and inner thinner
layer with different sizes. Hence, light, when travels through the ceramics possess
interference effect and scattered light from the second layer, has a phase shift due to
the interference of scattered light from the first layer. This technique has been utilized
in producing red glass, and Satsuma glass used in Japan during the mid-nineteenth
century. Satsuma glass can be brightened by ruby colour by using the absorption
properties of Cu NPs [1].
In 1857, Michael Faraday developed a systematic synthesis of colloidal gold
solutions and studied optical and coagulation properties of colloidal gold [3]. This is
considered the first scientific record on NP synthesis. The study gave an idea about the
optical properties of a colloidal gold solution. This leads Mie to explain the specific
colours of the colloidal metallic particle solution [1]. The birth of the concept of NP
was originated in the pharmaceutic field, related to targeted drug delivery. Professor
Peter-Paul Spieser did one of the pioneering works on NPs in this field at Eidgenössische Technische Hochschule Zurich. His research group investigated polyacrylic
bead for oral therapy and started focusing on synthesizing microcapsules. Eventually, in the 1960s they developed first NPs for vaccination purpose and drug delivery
approaches [4]. Later, it started to synthesize several NPs for various purposes.
In this book chapter, we review the different approaches in synthesizing MNPs for
biomedical applications. The following sub-section describes the properties of NPs,
the formation of NPs, and theories behind it. The second section briefly explains topdown methods in synthesizing MNPs and their limitations. The bottom-up approach
K. Illath et al.
1 Introduction
The history of nanoparticles (NPs) dates back to almost 4500 years ago; ancient
humans utilized natural asbestos nanofibers in developing ceramic matrices. Four
thousand years ago, Egyptians used ~5 nm diameter lead sulfide NPs for hair dye
treatment, synthesized from a chemical synthetic process. ‘Egyptian blue,’ a multifaceted mixture of cuprorivaite and silicon dioxide, is considered as the first synthetic
material prepared from nanometer-sized glass and quartz, used by Egyptians around
third century BC. Later in the thirteenth- and fourteenth-century BC, Egyptians
and Mesopotamians started synthesizing glass from metallic nanoparticles (MNPs).
During the Bronze age, surface plasmon excitation of cobalt nanoparticles (Co NPs)
has been utilized in colouring the surface of red glass. Co NPs were also used in Celtic
red enamels [1]. Another notable pioneering work in the MNPs era is the Lycurgus
cup, used back to fourth century AD. The cup can change its colour depends on
the location of the light source. Further analysis of this cup revealed that it consists
of minimal quantities of ~70 nm gold and silver crystals with an appropriate molar
ratio of 14:1, which results in its surprising characteristics [1, 2]. Later, gold and
silver nanoparticles (Au & Ag NPs) in appropriate ratios have been utilized in red
and yellow stained glass to decorate churches. Optical properties of Ag and copper
nanoparticles (Cu NPs) were employed in glazed ceramics by Mesopotamians. It
displays bright green and blue colours under particular specific radiation. Investigation revealed that ceramics has an outer double layer of Ag NPs and inner thinner
layer with different sizes. Hence, light, when travels through the ceramics possess
interference effect and scattered light from the second layer, has a phase shift due to
the interference of scattered light from the first layer. This technique has been utilized
in producing red glass, and Satsuma glass used in Japan during the mid-nineteenth
century. Satsuma glass can be brightened by ruby colour by using the absorption
properties of Cu NPs [1].
In 1857, Michael Faraday developed a systematic synthesis of colloidal gold
solutions and studied optical and coagulation properties of colloidal gold [3]. This is
considered the first scientific record on NP synthesis. The study gave an idea about the
optical properties of a colloidal gold solution. This leads Mie to explain the specific
colours of the colloidal metallic particle solution [1]. The birth of the concept of NP
was originated in the pharmaceutic field, related to targeted drug delivery. Professor
Peter-Paul Spieser did one of the pioneering works on NPs in this field at Eidgenössische Technische Hochschule Zurich. His research group investigated polyacrylic
bead for oral therapy and started focusing on synthesizing microcapsules. Eventually, in the 1960s they developed first NPs for vaccination purpose and drug delivery
approaches [4]. Later, it started to synthesize several NPs for various purposes.
In this book chapter, we review the different approaches in synthesizing MNPs for
biomedical applications. The following sub-section describes the properties of NPs,
the formation of NPs, and theories behind it. The second section briefly explains topdown methods in synthesizing MNPs and their limitations. The bottom-up approach