ABSTRACT
Gold nanoparticles were synthesized by reducing aqueous chloroauric
acid (HAuCl4) with three different bacteria. Various microorganisms
were verified to see how feasible they will be in synthesizing gold
nanoparticles. Three microorganisms were screened and found to produce
gold nanoparticles effectively. These bacteria include; Bacillus
megaterium, Bacillus subtilis and serratia mercensis mercensis.
Microorganisms in the synthesis of nanoparticles appear as an
environmentally friendly and exciting approach. Different sizes and
shapes of gold nanoparticles are produced by the various microorganisms
used. The particle sizes and shapes were controlled by pH. The
microorganisms and the HAuCl4 were incubated at pH of 3 and 7. It was
observed that spherical nanoparticles were observed at of pH 7 whiles
nanoplates were observed at pH 3.
Poor bioavailability and intrinsic toxicity are some of the
problems facing conventional therapies and as a result have compromised
the therapeutic efficacy of many otherwise beneficial drugs. Some of
these shortcomings of the conventional therapies are been overcome by
the design of nanoscopic systems to change the pharmological and
therapeutic properties of molecules. In order to enhance the
bioavailability of targeted site, nanosystems are often accumulated at
higher concentrations than normal drugs. Systems toxicity is greatly
reduced when the enhanced drug is targeted to the diseased tissue.
Diagnosis of cancer is often late as most of them are hidden or
known metastasis. The ability of gold nanoparticles to absorb light in
the visible and near-infra red (NIR) region depends strongly on the
shape and size of the nanostructure. Moreover, the amount of cells that
can be taken by gold nanoparticles is size dependent with optimal
diameter of 50 nm for spherical nanoparticles.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Statement of Introduction and Background
Synthesis of metal nano particles has received much attention in
recent times because of their numerous applications in catalysis [3],
sensor technology [1], biological labeling [5], optoelectronics
recording media and optics [2]. The mode of producing these nano
particles can be done by chemical, biological and physical methods [3,
6]. Chemical and physical methods were mostly used in synthesizing gold
nanoparticles; however there has been an appreciable rise in the
biological synthesis of nano particles in the past decade. This is
because biological synthesis is ecologically friendly. Moreover, the
method is non toxic and produces a clean product.
Nanoparticles are particles with one or more dimensions on the
order of nano particles (10-9 meters) [7]. Nano scale region has
received much attention in material science in recent years because of
their numerous potential applications. There has been significant
research work to describe particles of this size. Since particles of
nano meter behave differently from their bulk size counterparts,
research work to describe particle size has been challenging. This is
seen when the physical properties of the material changes when the
particle size decreases. This phenomenon comes about when physical
quantities, such as magnetic domain size, grain size etc have similar
size.
Nano scale research is of significant contribution in material science and technology for
the development of new materials with improved properties. Wear
resistance, elasticity, strength, thermal conductivity, electrical
conductivity etc are some of the properties of importance. Materials to
perform effective, efficient and complex tasks have also been
researched. The medical application of nano technology and related
research is nano medicine. Nano medicine comprises of the various
medical applications of nano materials to medicine.
In medical application system, nano particles are been used to
deliver drugs, heat, light or other substances to cells such as cancer
cells. Direct treatments of diseased cells are made possible when
engineered particles are attracted to the diseased cells. X ray
activated nanoparticles have the capacity to destroy cancer cell which
cling to them. The damage caused to healthy tissue by this method is
much less than in radiation therapy. Moreover nano particles such as
alumno-silicates reduce bleeding quickly in traumatic patients by
clotting blood quickly and absorbing water. In diagnostic and imaging
techniques cancer tumors in patients can be located using quantum dots
(qdots). Magnetic Resonance Imaging (MRI) images of cancer tumors also
can be improved using iron oxide nanoparticles. Disease indicators can
be detected at the early stages when nanoparticles are allowed to attach
themselves to protein or other molecules.
Like most metals, gold nanoparticles can be produced. As a pure and
a naturally occurring element, gold is very unreactive, malleable and
ductile. However it reacts in a mixture of acids such as aqua regia and
cyanide solutions. Gold has the ability to dissolve in mercury but it
does not react with it and does not oxidize in water. Gold normally
occurs in alluvial deposits, nuggets or occurs in veins.
Gold has been used as a monetary value since history because it is a
precious metal. Furthermore, it is also used in jewelry such as chains,
bracelets etc. Apart from its traditional uses, gold is also used in
many industrial applications. Due to its resistance to oxidative
corrosion and as a good conductor of electricity, gold is used in
dentistry and electronics. It is also used in the food and drink
industry.
The non reactivity property of gold facilitates its use in
medicine. In diagnosis, radioactive gold is monitored as a beta emitter,
as it passes through the body when it is injected in a colloidal
solution. For a person who finds it difficult to close the eyes
completely, i.e. lagophthalmos, gold particles are used to remedy the
condition by impacting the gold nano particles in the upper eyelid.