Green synthesis of antimicrobial silver nanoparticles utilizing various plant extracts

다국어 초록 (Multilingual Abstract)

This paper investigated the antimicribial activity of green synthesized silver nanoparticles using various plant extracts. 4 kinds of fruits extracts (Malus domestica, Poncirus trifoliate, Lycopersicon esculentum, and Juglans regia) and 20 kinds of medicinal plants were used for synthesis. Among them, the silver nanoparticles using Lycopersicon esculentum and Areca catechu extracts were verified the physical and biological properties. Analysis of the particle characteristics by UV-Vis spectrophotometer, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), Dynamic light scattering (DLS) and Fourier-transform infrared spectroscopy (FT-IR) confirmed that the Lycopersicon esculentum and Areca catechu extracts effectively served as reductants and capping agents. Minimum inhibitory concentration (MIC) tests and Minimum bactericidal concentration (MBC) were conducted to confirm antifungal and antibacterial activity against 5 Candida species (3 antibiotics-susceptible species and 2 antibiotics-resistant species) and 6 bacteria species (3 antibiotics-susceptible species and 3 antibiotics resistant species). In all the tested species, the silver nanoparticles inhibited the growth of microbe. Moreover, the SEM images of Candida and bacteria species treated with silver nanoparticles synthesized using natural extracts of Lycopersicon esculentum and Areca catechu showed silver nanoparticles adhered to the surface of microbe, which induced pore formation in the membranes and prevented their normal growth. Ultimately, these abnormal forms of microbe were thought to be less able to form biofilms than normal microbe.
These antibacterial, antifungal, and antibiofilm activities of silver nanoparticles against microorganism are expected to be utilized in various fields and contribute to developments in the nanomedicine field, in particular.

목차 (Table of Contents)

• CONTENTS
• ABSTRACT...................................................................................................ⅰ
• CONTENTS..................................................................................................ⅳ
• LIST OF FIGURE........................................................................................ⅸ
• LIST OF TABLE...........................................................................................ⅹⅴ
• Chapter Ⅰ. Background
• 1. What is silver nanoparticles.......................................................................1
• 2. Green synthesis of silver nanoparticle......................................................3
• Chapter Ⅱ. Inhibitory Activity of Silver Nanoparticles Synthesized Using Lycopersicon Esculentum Against Biofilm Formation in Candida Species.
• 1. Introduction...............................................................................................5
• 2. Materials and Methods.............................................................................8
• 2.1. Preparation of fruit extracts..................................................................8
• 2.2 Screening test of AgNPs synthesis by visual inspection...................................................................................................10
• 2.3. Preparation of silver nanoparticles..................................................10
• 2.4. Characterization of the silver nanoparticles ......................................10
• 2.5. Antifungal and antibiofilm activity of the silver nanoparticles.............................................................................................11
• 2.5.1. Minimum inhibitory concentration of silver nanoparticles against Candida species...............................................................................11
• 2.5.2. Inhibitory effect of silver nanoparticles on pre-formed biofilms.......................................................................................14
• 2.5.3. Morphology of Candida biofilm treated with silver nanoparticles.............................................................................14
• 2.6 Statistical analysis...................................................................15
• 3. Results and Discussion.................................................................15
• 3.1 Screening test of AgNPs synthesis..................................................15
• 3.2. Characterization of the silver nanoparticles (AgNPs)........................17
• 3.2.1. UV-Vis spectral analysis......................................................17
• 3.2.2. Scanning electron microscopy (SEM) image........................19
• 3.2.3. Dynamic light scattering (DLS) .............................................21
• 3.2.4. Fourier transform-infrared spectroscopy (FT-IR) .....................23
• 3.3. Antifungal and antibiofilm activity of the silver nanoparticles............25
• 3.3.1. Minimum inhibitory concentration of the silver nanoparticles..25
• 3.3.2. Inhibitory effect of silver nanoparticles on pre-formed biofilms.................................................................................................27
• 3.3.3. Morphology of Candida biofilm treated with silver nanoparticles.......................................................................................29
• Chapter Ⅲ. Antibacterial activity of Green-Synthesized Silver Nanoparticles Using Areca catechu extract against antibiotics resistant bacteria
• 1. Introduction............................................................................................34
• 2. Materials and Methods..........................................................................35
• 2.1. Medicinal plant...................................................................................35
• 2.2. AgNPs synthesis using various medicinal plants.................................37
• 2.3. Optimization of AgNPs synthetic condition using A.catechu extract...........................................................................................................37
• 2.4. Characterization of the synthesized AgNPs......................................38
• 2.5. Well diffusion test of AgNPs.............................................................38
• 2.6. Minimum inhibitory concentration and Minimum bactericidal concentration of AgNPs..............................................................................41
• 2.7. Morphology of the antibiotic resistant-bacteria treated with AgNPs...41
• 2.8. Statistical analysis...............................................................................42
• 3. Results and Discussion.....................................................................42
• 3.1. The AgNPs synthesis using various medicinal plants........................42
• 3.2. Optimization of AgNPs synthesis condition using Areca catechu extract.........................................................................................................45
• 3.3. SEM image and particle size distribution of the synthesized AgNPs.........................................................................................................49
• 3.4. FT-IR analysis......................................................................................51
• 3.5. Antimicrobial activity of synthesized AgNPs......................................53
• 3.5.1. Well diffusion assay....................................................................53
• 3.5.2. The observation of antibiotics resistant bacteria treated with AgNPs using SEM...............................................................................64
• Chapter Ⅳ . Conclusion..............................................................................68
• REFERENCES................................................................................71
• 국문요약........................................................................................82