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ACKNOWLEDGEMENT I would like to express my gratitude Assoc. Prof. Dr. Tran Thi Nhu Mai for her supervisor and guidance throughout all of my researches. A very special thanks goes out to Professor Catherine J. Murphy and her groups members, who gave truly help the progression and smoothness of the internship program in University of Illinois at Urbana Champaign. I am also thankful all of other members of Laboratory of Organic Catalyst for their helps during my working time. ABSTRACT Nanoparticles, already widely applied in diverse fields from catalysis to bioimaging, have undergone tremendous development in the past two decades, where size control of spherical nanocrystals of semiconductors, metals and insulators has been achieved for almost any material. The published results has proven that gold nanomaterials possess strong and unique characteristics being hopeful to apply on a variety of fields, especially in Chemistry for catalyst purposes or biochemical purposes. In this research, the seeded growth and hydrolysis Stobers method was applied to synthesize and overcoat gold nanorods aiming to biomedical purposes. Moreover, the hydrothermal method was used to nail gold nanoparticles on the Si template orienting to the green catalyst. The results showed by physical methods such as Zetapotential, transmission electron microscope (TEM) or UVVis. EDX and N2 adsorptiondesorption measurements have confirmed the effective of these methods.
Phan Thi Thanh Binh K52 Advanced Program Chemistry VIETNAM NATIONAL UNIVERSITY, HANOI HANOI UNIVERSITY OF SCIENCE FACULTY OF CHEMISTRY Phan Thi Thanh Binh STUDY ON SELECTED SYNTHESES OF GOLD NANOPARTICLES Submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Chemistry (Advanced Program) Hanoi - 2012 Phan Thi Thanh Binh K52 Advanced Program Chemistry VIETNAM NATIONAL UNIVERSITY, HANOI HANOI UNIVERSITY OF SCIENCE FACULTY OF CHEMISTRY Phan Thi Thanh Binh STUDY ON SELECTED SYNTHESES OF GOLD NANOPARTICLES Submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Chemistry (Advanced Program) Hanoi - 2012 Phan Thi Thanh Binh K52 Advanced Program Chemistry ACKNOWLEDGEMENT I would like to express my gratitude Assoc. Prof. Dr. Tran Thi Nhu Mai for her supervisor and guidance throughout all of my researches. A very special thanks goes out to Professor Catherine J. Murphy and her group's members, who gave truly help the progression and smoothness of the internship program in University of Illinois at Urbana Champaign. I am also thankful all of other members of Laboratory of Organic Catalyst for their helps during my working time. Phan Thi Thanh Binh K52 Advanced Program Chemistry ABSTRACT Nanoparticles, already widely applied in diverse fields from catalysis to bio- imaging, have undergone tremendous development in the past two decades, where size control of spherical nanocrystals of semiconductors, metals and insulators has been achieved for almost any material. The published results has proven that gold nano- materials possess strong and unique characteristics being hopeful to apply on a variety of fields, especially in Chemistry for catalyst purposes or biochemical purposes. In this research, the seeded - growth and hydrolysis Stober's method was applied to synthesize and overcoat gold nanorods aiming to biomedical purposes. Moreover, the hydrothermal method was used to nail gold nanoparticles on the Si template orienting to the green catalyst. The results showed by physical methods such as Zeta- potential, transmission electron microscope (TEM) or UV-Vis. EDX and N 2 adsorption/desorption measurements have confirmed the effective of these methods. Phan Thi Thanh Binh K52 Advanced Program Chemistry Table of Contents Table of Contents 5 INTRODUCTION 8 CHAPTER 1: OVERVIEW OF GOLD NANOPARTICLES 9 1.1 BACKGROUND OF METAL NANOPARTICLES 9 1.2 OVERVIEW OF GOLD NANOPARTICLES 10 1.2.1 Properties and Applications 11 1.2.2 Synthesis and Functionalization 20 1.3 GOLD NANORODS 29 1.3.1 Optical properties 29 1.3.2 Synthesis methods 31 1.3.3 Silica coating 34 1.3.4 Applications 35 CHAPTER 2: EXPERIMENT 36 2.1 Seeded - growth method to synthesize gold nanorods 36 2.2 Hydrolysis Stober method to silica - coating gold nanorods 36 2.3 Hydrothermal method to synthesize gold nanoparticles template 37 2.4 Characterization Methods 38 CHAPTER 3: RESULTS AND DISCUSSIONS 44 3.1 PURPOSES 44 3.2 SYTHESIS AND CHARACTERIZATION OF GOLD NANORODS 45 3.2.1 The effects of AgNO3 volume on obtained gold nanorods 46 3.2.2 Effects of PEG - coating and silica - coating on gold nanoparticles 48 3.3 SYNTHESIS AND CHARACTERIZATION OF AU/SI (Au/Si_01) 53 3.2.1 N2 adsorption-desorption measurements 55 3.2.2 TEM, EDX and AAS methods 56 3.4 PROSPECTIVE APPLICATIONS 58 3.4.1 Gold nanorods 58 3.4.2 Au/Si material 59 CONCLUSION 61 REFERENCE 62 Phan Thi Thanh Binh K52 Advanced Program Chemistry LIST OF FIGURES Figure 1: Exponential growth in the number of publication on gold nanotechnology and nano- medicine over the two past decades.[6] 11 Figure 2: Conversion of glucose to gluconic acid in alkaline aqueous solution 12 Figure 3: Approaches of loading/unloading therapeutics 17 Figure 4: Loading drugs into the interior of gold nanoparticles 18 Figure 5: Scheme of sensing layer preparation using both peptide and antibody 19 Figure 6: Gold nanodendrites 20 Figure 7: Gold Nanorods [21] 21 Figure 8:Sharpened nanorods [22] 21 Figure 9: Nanocages/nanoframes 22 Figure 10: Nanoshells [24] 22 Figure 11: Hallow gold nanosphere 23 Figure 12: (a) tetrahedra/octahedra/cubes/icosahedra, (b) rhombic dodecahedra, (c) octahedra 23 Figure 13: Nanocubes 23 Figure 14: Complex nanostructures 24 Figure 15: (a) hydrophobic entrapment, (b) electronstatic adsorption[6] 27 Figure 16: Silance conjugation of gold nanoparticle 28 Figure 17: Electron micrograph of a silica sphere sample 28 Figure 18: UV- Vis spectra of gold nanorods with aspect ratios: (A) 1.42 ± 0.32, (B) 1.82 ± 0.49, (C) 2.31 ± 0.55, (D) 2.65 ± 0.43, and (E) 2.80 ± 0.37 30 Figure 19: Illustration of changes of gold nanorod colors due to aspect ratio 30 Figure 20: Scheme of template approach of gold nanorods 31 Figure 21: a, Scheme of electrochemical approach of gold nanorods b, TEM of gold nanorods at other aspect ratios obtained by elec. method 32 Figure 22: Illustration for gold nanorods growth in the absence of silver ion 33 Figure 23: Proposed formation of gold nanoparticles 33 Figure 24: Illustration: gold nanorods growth in the presence of silver ion 34 Figure 25: Scheme of seeded - growth method procedure 45 Figure 26: UV - VIS of rainbow solutions 46 Phan Thi Thanh Binh K52 Advanced Program Chemistry Figure 27: The formation of gold nanorods in the presence of Ag 47 Figure 28: TEM image of 10Ag sample 47 Figure 29: Scheme of PEG, silica - modification procedure 48 Figure 30: TEM of mPEG - SH coated gold nanorods PEG-6Ag 50 Figure 31: UV - VIS of PEG-6Ag and Sil-6Ag 51 Figure 32: TEM of Silica - coated nanorods Si-6Ag 52 Figure 33: Scheme of synthesis template procedure 53 Figure 34: Scheme of preparing Au/Si procedure 54 Figure 35: BET of Au/Si_01 55 Figure 36: Pore distribution of Au/Si_01 56 Figure 37: TEM image of Au/Si_01 57 Figure 38: EDX spectrum of Au/Si 58 Figure 39: Typical properties and applications of gold nanorods [43] 59 Figure 40: Products containing calcium gluconate 60 LIST OF TABLES Table 1: Gold nanoparticles in photothermal therapy applications 15 Table 2: Summary of synthetic approaches to obtain various gold nanostructures 24 Table 3: Outline of relation between stability and zeta-potential 40 Table 4: Data of rainbow gold nanorods 46 Table 5: BET - data of Au/Si_01 55 Phan Thi Thanh Binh K52 Advanced Program Chemistry INTRODUCTION Normally, we also know that pure gold is a transition metal in the group 11 of periodical table. It has a very high melting point and shows the nature as one of the least reactive metals. However, it exhibits a beautiful appearance, amazing malleability and ductility, of course, good conductivity. That means why gold have been more widely used to craft expensive ornaments or gild electronic accessories than apply on chemical field. However, in the recent researches, the scientists have discovered that gold on nanoscale represents a huge number of predominant effects that are full of promises to play the role of aurotherapy, photothermal argents, and especially catalysis, optical materials and biomedicine such as drug therapy or biosensor. In fact, Murphy et al.[1] and Nikoobakht and El-Sayed[2] have been successful to demonstrate a colloid method to synthesize mono - disperse nanorods at high yield based on seeded growth method. After that, to increase the biological compatibility, nanorods will be coated and functionalized by other materials, generally for instance, a variety of silicates or polymers, which have the functional groups to be similar to acid amines, enzymes such as thiolate, amines, carboxylate etc. In the first part of this research, I have already prepared nanorods based on seeded - growth theory in the Phan Thi Thanh Binh K52 Advanced Program Chemistry presence of silver and cationic surfactant CTAB and . Then the Stober method was used to overcoat the nanorods by silica (i.e, TEOS) On the other hands, although gold is the most inert of all metallic elements, but many studies have proven that gold nanoparticles also have appropriate properties as heterogeneous catalysts. The right explanation has been debated, however, one possibility explaining this phenomenon might be because of the availability of surface gold atoms with low coordination number and the associated electrons density for whatever reactions is being catalyzed [3]. But it cannot deny that nanogold has played an important role in the Chemistry as the green catalyst for many reactions, especially for Organic chemistry. So we have built a process to nail the gold - nanoparticles on the template reigned P123 and TEOS by hydrothermal method orienting to catalyze for reaction of producing calcium gluconate from natural D - Glucose. CHAPTER 1: OVERVIEW OF GOLD NANOPARTICLES 1.1 BACKGROUND OF METAL NANOPARTICLES Just as in bulk metals, electrons in the conduction band of nanoscale metals are free to oscillate upon excitation with incident radiation, referred to as the localized surface plasmon resonance (LSPR). However, on the nanoscale, the oscillation distance is restricted by the nanoparticle size. For gold nanoparticles, LSPR corresponds to photon energies in the visible wavelength regime, giving rise to significant interest in their optical properties. These optical characteristics include strong plasmon absorption, resonant Rayleigh scattering, and localized electromagnetic fields at the nanoparticle surface. Actually, plasmon absorption in metal nanoparticles is highly dependent on nanoparticle shape, size, and dielectric constant of the surrounding medium [4]. One area of catalysis that is developing at a rapid pace is nanocatalysis. Striking novel catalytic properties including greatly enhanced reactivities and selectivities have been reported for nanoparticle (NP) catalysts as compared to their bulk counterparts. In order to harness the power of these nanocatalysts, a detailed understanding of the origin of their enhanced performance is needed [5]. Many experimental studies on nanocatalysts have focused on correlating catalytic activity with particle size. While Phan Thi Thanh Binh K52 Advanced Program Chemistry particle size is an important consideration, many other factors such as geometry, composition, oxidation state, and chemical/physical environment can play a role in determining NP reactivity. However, the exact relationship between these parameters and NP catalytic performance may be system dependent, and is yet to be laid out for many nanoscale catalysts. Clearly, a systematic understanding of the factors that control catalyst reactivity and selectivity is essential if trial and error methods are to be avoided. 1.2 OVERVIEW OF GOLD NANOPARTICLES The first scientific report describing the production of colloidal gold nanoparticles was published in 1857 when Michael Faraday found that the ‘‘fine particles’’ formed from the aqueous reduction of gold chloride by phosphorus could be stabilized by the addition of carbon disulfide, resulting in a "beautiful ruby fluid". Actually, the Human has a huge step up to approach the gold nanoparticles. Nowadays, most colloidal synthetic methods for obtaining gold nano particles follow a similar strategy, whereby solvated gold salt is reduced in the presence of surface capping ligands which prevent aggregation of the particles by electrostatic and/or physical repulsion. Gold nanoparticles have been used in biomedical applications since their first colloidal syntheses more than three centuries ago. Actually, over the past two decades, their beautiful colors and unique electronic properties have also attracted serious attention due to their historical applications in art, medicine and current applications in enhanced optoelectronics and photovoltaics. In spite of their modest alchemical beginnings, gold nano-particles possess physical properties that are significantly different from both small molecules and bulk materials, as well as from other nano-scale particles. -Moreover, their unique combination of properties is just beginning to be fully realized in range of medical diagnostic and therapeutic applications [6]. [...]... bond strength between anchoring groups and the gold surface plays a critical role in determining the subsequent functionality Besides, packing density and surface energetics also make equally important contributions Functionalization of gold nanoparticles follows largely on work initially conducted on the formation of self-assembled monolayers (SAMs) [29] of molecules on planar gold and later in studying... measurements On the other hand, spectroscopic measurements are often the easiest methods for monitoring surface processes such as dissolution and precipitation, adsorption and electron transfer [36] When gold nanorods are illuminated at the proper optical frequencies, the conduction band electrons in the gold are excited, resulting in a resonant, coherent oscillation of these electrons This resonance condition... incorporation of gold on less hindered facets Otherwise, propose that silver bromide complexes may not explain anisotropic growth, and instead argue that underpotential deposition of a monolayer or submonolayer of elemental silver on the gold nanorod surface is of significance Figure 24: Illustration: gold nanorods growth in the presence of silver ion Differing degrees of silver passivation on the {110}... for co-conjugated drugs Gold nanoparticles absorb light with high efficiency (extinction coefficient B10) in the near-infrared (NIR) region of the electromagnetic spectrum, where attenuation by biological fluids and tissues is minimal Gold nanoparticles have the advantage of higher absorption cross section, higher solubility, efficient absorption at longer wavelengths, and facile conjugation with targeting... sites available on the {100} and {110} faces of the crystalline rods The binding of CTAB, ultimately as a bilayer [12], on the side of the rod blocks the deposition of further gold to the side and promotes the growth from the ends Figure 23: Proposed formation of gold nanoparticles It was predicted that the CTAB micellar structure also promoted the deposition of metal at the tips of gold seed particles... weight alcohols [32] As the content of Stober's publication, the silica spheres had been synthesized in the high concentration of ammonia because of the formation of spherical particles Initially, pure alcohol or alcohol mixtures, saturated alcoholic ammonia solution, ammonium hydroxide, and water were mixed well at strictly definite concentrations Subsequently, an exact amount of alkyl silicate was added... aggregation [35]) have been proposed to elucidate the chemical/physical growth mechanism of silica dividing the formation of silica into two events: nucleation and growth The monomer addition model supports a mechanism where an initial burst of nucleation, growth occurs through the addition of hydrolyzed monomers to the particles surface Besides, the controlled aggregation claims that nucleation happens... properties make gold nanoparticles promising candidates for photothermal therapy of cancer and various pathogenic diseases The common use of gold nanoparticles in photothermal therapy are abundant in the literature is sum up in Table 1 Table 1: Gold nanoparticles in photothermal therapy applications Nanoform Gold nanoshells Particle size (nm) silica 110 - 150 Available region Vis - NIR Applications ablating... expounds upon the use of gold nanoparticles of different shape/size in drug delivery applications, each categorized by the previous methods in which their active agent is loaded and/or released Phan Thi Thanh Binh K52 Advanced Program Chemistry Figure 3: Approaches of loading/unloading therapeutics into/from gold nanoparticles The illustration describes the partitioning and diffusion-driven release of hydrophobic... chemistry Applications of gold nanoparticles in Vietnam In fact, the study of gold nanoparticles has not been truly developed in Vietnam due to a lot of difficulties in required facilities and expenditure However, recently, Institute of Chemistry - Vietnam Academy of Science and Technology has been successful to make electrochemical sensors based on gold nanopartcles In the first publication in 2009, they . system dependent, and is yet to be laid out for many nanoscale catalysts. Clearly, a systematic understanding of the factors that control catalyst reactivity and selectivity is essential if trial. adsorption/desorption measurements have confirmed the effective of these methods. Phan Thi Thanh Binh K52 Advanced Program Chemistry Table of Contents Table of Contents 5 INTRODUCTION 8 CHAPTER. nanostructures 24 Table 3: Outline of relation between stability and zeta-potential 40 Table 4: Data of rainbow gold nanorods 46 Table 5: BET - data of Au/Si_01 55 Phan Thi Thanh Binh K52 Advanced