WHAT ARE SILVER NANOPARTICLES?
Silver Nanoparticles are 3-Dimensional material, of which at least one dimension is Quantum confined. In simple words, Silver Nanoparticles are having at least one dimension in size range of 1 to 100 nanometer (Sometimes, Particles having size greater than 100 nanometer can be called as Nanoparticles depending on the Quantum Confinement effect). Silver Nanomaterials can be classified into four categories mainly:
1-Dimensional Silver Nanomaterials – Silver Nanowires, Nanofibers and Nanorods etc.; 2-Dimensional Silver Nanomaterials – Silver Films and Coatings etc.; 3-Dimensional Silver Nanomaterials – Silver Nanocubes, Nanoflowers, Nanoring, Nanotriangles and Nanoporous Structures etc.; 0-Dimensional Silver Nanomaterials – Silver Quantum Dots.
HOW SILVER NANOPARTICLES DIFFER FROM ORDINARY SILVER?
Ordinary Silver is light Gray in color, but color of Silver Nanoparticles changes from Yellow to Reddish depending on the size of Nanoparticles as seen in above image. Ordinary Silver is only used for few applications like Jewelry and foil papers. But Silver Nanoparticles are having wide range of applications in Electronics, Paints, Coatings, Soap, Detergents, Bandage and many other medical applications. Our researchers didn’t stop yet, we are finding more and more applications of Silver Nanoparticles every year.
SYNTHESIS OF SILVER NANOPARTICLES:
Silver Nanoparticles can be synthesized through various techniques. For better understanding, synthesis of Silver Nanoparticles can be categorized into mainly two categories:
1. Top Down Techniques – Ball Milling, Grinding, Laser Ablation and Physical Vapor Deposition (PVD) etc.
2. Bottom Up Techniques – Simple Chemical Reduction, Hydro-thermal, Micro-organism & Leaf extract Synthesis and many more.
Simple Reduction Technique:
1. Take the available Silver precursor (e.g. Silver Nitrate, Silver Acetate or Silver Sulfate) in water.
2. Then add Capping/Stabilizing agent (e.g. PolyVinyl Alcohol (PVA), PolyVinylPyrrolidone (PVP) or CTAB etc.)
3. Now add reducing agent (e.g. Hydrazine Hydrate, Sodium Borohydride etc.) for the formation of Silver Nanoparticles.
NOTE: Precursor : Capping : Reducing = 1 : 2 : 0.7 & Precursor : Water = 0.001 : 1 (This ratio is not fixed, you have to optimize it to get good results)
Please explore InstaNANO.com for more synthesis techniques.
CHARACTERIZATION OF SILVER NANOPARTICLES:
UV-Vis Absorption of Silver: Absorption peak of Silver Nanoparticles is obtained around 420nm.
X-Ray Diffraction of Silver: XRD of Silver mineral is given
PROPERTIES & APPLICATIONS OF SILVER NANOPARTICLES:
Silver Nanoparticles are having various properties but mainly known for these unique properties:
Anti-Microbial Properties: It is known form the past centuries that Silver is having very good anti-microbial properties. In Silver Nanoparticles, anti-microbial properties are very high. At present, Silver Nanoparticles are being used in many medical applications because of its highly active anti-microbial properties. Research is going on the Silver Nanoparticles coated Bandage as it can kill bad microbes and lead for better healing at some injured body part. A research is also going on using Silver Nanoparticles in the food packaging so that food can survive for longer time without any contamination.
Anti-Fungal Properties: Silver highly participate in anti-fungal properties. Various researches are going on these days to use Silver Nanoparticles protection in food items, paint industries, textile industries etc. In future, we will be surely having some items which will be highly hygienic, pure and impurity-free; which will only be possible by Silver Nanoparticles.