Biosynthesis of Silver Nanoparticles by sundried Aleurites moluccana leaf and yeast pichia pastoris

摘要

由于纳米银的性质和它的粒径、粒径分布和形貌息息相关，因此如何调控纳米银的粒径和形貌引起了研究者的广泛关注。本研究选取了两种生物质--石栗叶和毕赤酵母菌粉作为还原剂来制备纳米银，研究了反应时间、温度、搅拌速度、生物质/银离子的比值和pH值等条件对纳米银的粒径和形貌的影响，并利用紫外-可见分光光度计(UV-Vis)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和傅立叶变换红外光谱仪(FTIR)等多种分析方法来表征所形成的纳米银。 利用石栗叶作为还原剂，80℃时所制备的纳米银的平均粒径大约为31.1 nm，当温度升高到100℃时，所合成的纳米银的平均粒径减小为13.2 nm。增大搅拌速度使得纳米银的紫外-可见吸收峰的位置发生了蓝移，峰的强度减弱，当搅拌速度从10 rpm增大到30nm，所获得的纳米银的平均粒径有轻微减小(26.3 nm→25.5 nm)。而增加石栗叶的浓度则会使得紫外，可见吸收峰的峰强变大，峰的位置发生了蓝移，这说明了随着石栗叶浓度的增加，所制得的纳米银的粒径逐渐减小。此外，我们发现了pH值对于纳米银的粒径也有很大的影响，当溶液的pH逐渐增大时(5→9→12)，所制得的纳米银的粒径逐渐减小(11.9 nm→11.3 nm→8.7 nm)。 利用毕赤酵母菌粉作为还原剂时，本研究选取了硝酸银和银氨来作为银前驱体，比较了二者的差异，研究发现利用银氨作为前躯体对的还原速率要比用硝酸银时快。利用硝酸银作为前躯体时，当pH≤4时，溶液中没有纳米银生成；当pH>4时，随着pH值的增大，所获得的纳米颗粒的粒径逐渐减小。而利用银氨作为前躯体时，pH≤4时，溶液中同样没有纳米银生成，随着pH值的增大(5→12)，纳米银的紫外-可见吸收峰逐渐蓝移(423 nm→418 nm)，说明了纳米银的粒径逐渐减小。随着搅拌速度的增大和温度的提高，纳米银的紫外-可见吸收峰的强度逐渐增大，但峰的位置没有发生变化，说明搅拌速度和温度对纳米银的粒径影响不大。银离子浓度一定时，所制得的纳米银的平均粒径随着毕赤酵母菌粉量的增大有轻微的增大(11.98 nm→12.97 nm)。而生物质浓度一定时，增大硝酸银的浓度，所制得的纳米银的紫外-可见吸收峰强度增大，但半峰宽明显变宽，说明溶液中纳米银发生了团聚。

目录

文摘

英文文摘

论文说明：LIST OF ABBREVIATIONS、LIST OF FIGURES、LIST OF TABLES

声明

ACKNOWLEDGEMENT

CHAPTER 1 INTRODUCTION AND LITERATURE SURVEY

1.1. Introduction and Emergence of Nanotechnology

1.1.1. What is nanoscicnce and nanotechnology?

1.1.2. Emergence of Nanotechnology

1.2. Properties and Applications of silver nanoparticles

1.2.1 Properties of silver nanoparticles

1.2.2. Applications of silver nanoparticles

1.3. Preparation methods of silver nanoparticles

1.3.1. Chemical methods

1.3.2. Physical methods

1.3.3. Biological methods

1.4. Factors affecting the biosynthesis process of silver nanoparticles

1.4.1 Effect of Temperature

1.4.2 Effect of pH

1.4.3 Effect of biomass concentration

1.4.4 Effect of Reaction Time

1.5. Aim, significance and content of this study

CHAPTER 2 MATERIALS AND METHODS

2.1. Reagents and instruments

2.2 Biosynthesis of silver nanoparticles using Aleurites moluccana leaves

2.2.1 Preparation of A.moluccana leaf biomass and reagents

2.2.2. Preparation of silver nanoparticles

2.3 Biosynthesis of silver nanoparticles using yeast pichia pastoris GS115

2.3.1 Preparation of P.pastoris biomass and reagents

2.3.2 Preparation of silver nanoparticles

2.4 Methods of characterization

2.4.1 Visual Inspection

2.4.2 UV-Vis spectra analysis

2.4.3 Fourier Transform infrared spectroscopy (FTIR) analysis

2.4.4 TEM characterization of silver nanoparticles

2.4.5 SEM characterization

CHAPTER 3 BIOSYNTHESIS OF SILVER NANOPARTICLES USING ALEURITES MOLUCCANA LEAF BIOMASS

3.1. Introduction

3.2 Characterization of silver nanoparticles synthesized by A. moluccana leaf

3.2.1. UV-Vis spectroscopy results

3.2.2. TEM results

3.2.3. FTIR spectroscopy results

3.3 Effect of synthesizing conditions on the synthesis process of silver nanoparticles

3.3.1. Effect of reaction time

3.3.2. Effect of pH on the synthesis process of silver nanoparticles

3.3.3. Effect of biomass concentration

3.3.4. Effect of temperature

3.3.5. Effect of rotate rate

3.4. Summery

CHAPTER 4 BIOSYNTHESIS OF SILVER NANOPARTICLES USING DEAD YEAST(Pichia Pastoris)

4.1 Introduction

4.2. Characterization of silver nanoparticles synthesized by pichia pastoris

4.2.1. UV-VIS spectroscopy results

4.2.2.SEM results

4.2.3. Fourier transform infrared spectroscopy (FTIR)

4.3. Effect of synthesizing conditions on the synthesis process of silver Nanoparticles

4.3.1. Effect of reaction time

4.3.2. Effect of pH

4.3.3. Effect of biomass concentration

4.3.4. Effect of temperature

4.3.5. Effect of rotate rate

4.3.6. Effect of silver amine ratio to biomass

4.4. Summary

CONCLUSION AND SUGGESTIONS

References