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.
