Title of Invention

METHOD OF MANUFACTURING NANO SILVER WITH CONTROLLED SIZE AND SHAPE

Abstract Fabrication of nanomaterials have gained importance due to the novelty in the properties of nanoparticles. Many recent research efforts have been focussed on the development of an economical and simpler method of synthesis of nano particles for both industrial, medical and other applications. Here we are concerned with the synthesis of silver nanopowder from its salt employing reduction process. Sodium Citrate ion finds a role as a reductant while the process temperature ranges between 293K-368K. It is supposed that the complexing of silver with the citrate ions and the process parameters dictate the size of the nanoparticles to be formed. The prepared NanoSilver particles have been dried by freeze drying process to avoid the property change at high temperature during the drying process. These materials might serve as ideal materials as catalysts, adsorbents, antibiotics etc.. These materials will have profound technological applications in the field of electronics, biotechnology, energy environment etc.
Full Text



Appendix - I
Specifications
Field of Invention:
The present invention is about the "Synthesis of Nanosilver from Silver Salts by Reduction reaction".
Background of the invention
Recent developments in Silver nanoparticles have opened new opportunities in the field of medicine. The potential for further development of metal based drugs and treatments as anti-microbial agents, are enormous and also of great importance with the evolution of drug resistant bacteria and threats from a range of viral diseases.
Many metal complexes have powerful anti-microbial activities and are already in common day to day use. But Silver is in use from olden days.
Many efforts have been devoted to the preparation of functional nanoparticals. However, utilization of nontoxic chemicals, environmentally benign solvents, cost effective and simple_procedures are some of the key issues.
Summary of the Invention:
Silver nanoparticals are prepared by the reduction of silver nitrate by Dimethyl Formamide / Tri Sodium Citrate / Sodium Borane which acts as a reducing agent at suitable Physical and chemical parameters. The prepared Nano Silver particles are collected using centrifugation. The collected wet Nanosilver is dried by applying Thermal and Microwave energy. The entire process is done in a dark room gives a better result.
Detailed Description of the preferred embodiments:
Step-1: The aqueous solution of Silver Nitrate and Tri Sodium Citrate is prepared separately. The Tri Sodium Citrate solution is slowly added with Silver nitrate solution at the temperature range between 35°C to 98°C.
Step-2; After the reaction completed, the fine nano Silver particles are collected with the help of centrifuge at 2,000 rpm to 10,000 rpm at the temperature from 18°C to 39°C for a duration of 30 min to 90 min.
Step-3: The collected fine particles are washed 3 to 7 times by de-ionized water and the step-2 is repeated.
Step-4: The collected wet particles are dried by one or all the following steps.
1. Applying microwave energy for at least 6 minutes in the dank and Inert / Oxygen / Sulphur free medium.
2. The sample is then placed in the freeze dryer of temperature range between -8°C to 20°C.
Step-5: If any dried and loosely adhered particles are found in the dried NanoSilver, the spongy material is fed into the high energy ball mill of speed range from 50 rpm to 3,000 rpm for at least 15 minutes.
Note: All these processes are done in dark and inert medium to yield better result.

Methods for preparing nanosilver
S:!vyer naropartlcals were prepared by the reduction of silver nirrate (AgN03) with tn sodium citrate. This method involves the reduction of metal ions at high temperature and gaseous environment. Tri sodium solution in water was added drop by drop to a heated solution of AgN03 while stirring. The mixture was kept heated for 10 min, and then it was cooled to room temperature. The morphology of the nanoparticle depends on parameters such as starting concentration, environmental conditions and the type of reducing agents used.
Basically in all these processes, some sort of external energy is necessary for the reduction to take place. It is also shown that tri sodium citrate and sodium carbonate both act as powerful reductants for silver salts.
The reduction of silver salts by Tri sodium citrate can be monitored from the color evolution of the solution. Visual observation shows that, as the reaction proceeds, the color shifts from, light yellow to dark brown, through orange and olive green, and then starts concentrating on the glass surfaces in contact with the solution, while the solution itself becomes increasingly clearer until it is completely transparent. This means that silver metal particles are formed in solution, which at some point sticks onto glass surfaces. This process is probably driven by electrostatic attraction between the particles with excess positive charge and negatively charged S1O2 surface,
The morphology of the resulting surfaces change with time, and depends on parameters such as starting concentration, illumination conditions, or specific silver salt used. It is remarkable that by careful control of these parameters, quite homologous films of reasonably monodisperse nanoparticles can be obtained. On the other hand, larger agglomerates can be observed during larger concentration and longer deposition times.
It is more advantageous to perform the experiment at higher temperature, since it takes only few hours for the completion of the reaction. On the other hand, at higher temperature, silver formation is so quick that silica polymerizes directly onto the silver particle surface.
Stabilization
The high surface energy of these nanoparticals makes them extremely reactive and most systems undergo aggregation without protection or passivation of their surfaces. Here dimethyl formamide is used as a stabilizing agent.
N,N-dimethyl-formamide (DMF) is one of the usual organic compounds used as a solvent for various processes. Several routes have been proposed for the oxidation of DMF, which normally involve evolution of H2 or C02 gas. No gas evolution has been observed during reactions at higher temperature.

Drying
The A/et "arcpai-tlcies are clrlec "y app.yi.ng direc: heat a: 7Ccc :c lCGcc ""cr :0 T'T.
The wet r.an-dparticles can also be dried using (microwave energy cr freeze drying. A
different approach to high temperature drying is the use of microwave heat. The advantage
of this method is based on a quick and very uniform heating of the whole sample with no
stirring.
>
Characterization
The quality and quantity of nanoparticles formed were studied. The morphology of silver nanoparticles was studied using XRD and Laser dynamic Scattering. The results showed us the prepared sample has more than 50% Of NanoSilver particles presented with range of 85 nm to 400 nm
Antimicrobial activity of NanoSilver
The antimicrobial activity of silver nanoparticles against E.coli was investigated as a model for gram negative bacteria. Bacteriological tests were performed in Luria-Bertani (LB) mediun on solid agar plates and in liquid systems supplemented with different concentrations of nanosized silver particles. These particles were shown to be an effective bactericide. The results confirmed that the treated E.coli cells were damaged, showing the formation of "pits" in the cell wall of the bacteria, while the silver nanoparticles were found to accumulate in the bacterial membrane. A membrane with such morphology exhibits a significant increase in permeability, resulting in death of the cell. These nontoxic nanometerials, which can be prepared in a simple and cost- effective manner, may be suitable for the formulation of new types of bactericidal materials.

Appendix II
Description of the invention
At present there are larger interest prevailing in understanding in the study of nanoscale matter with respect to their fundamental properties, organization to form superstructures and applications. The unusual physicochemical and optoelectronic properties of nanoparticles arise primarily due to the confinement of electrons within particles of dimensions smaller than the bulk electron derealization length, this process being termed as quantum confinement. The exotic properties of nanoparticles have been considered in applications such as optoelectronics, catalysis, reprography, single electron transistors and light emitters, nonlinear optical devices and photo-electrochemical applications.
An important area of research in nanotechnology deals with the synthesis of nanoparticles of different chemical compositions, sizes and controlled monodispersity. Indeed, nanoparticle shape control is a recent addition to the list of demands being made of newly emerging synthesis methods. Currently, there is a growing need to develop environmentally benign nanoparticle synthesis processes that do not use toxic chemicals in the synthesis protocol.
01. Title of invention
"Synthesis of Nanosilver from Silver Salts by Reduction Reaction".
02. Field of invention
The present invention is the preparation of IManoSilver particles by chemical route.
03. Background of invention with regard to the drawback of associated
with known art
The progress of technology and quality of life of mankind has always been closely knit with the progress in material science and material processing technology. Most material processing techniques are based on breaking up large chunk of a material into desired shapes and sizes, inducing strain, lattice defects and other deformations in the processed material. Recent developments in nanotechnology and the demonstration of various quantum size effects in nanoscale particles, implies that most of the novel devices of the future will be based on properties of nanomaterials. Each nanoparticle contains only about 3-107 atoms/molecules.
Lattice defects and other imperfections induced by the traditional material processing techniques will no longer be diluted by sheer number of atoms, when used for synthesizing nanoparticles. Furthermore, it is difficult to achieve size selective synthesis of such small particles, by using the formal approach.
Alternative synthetic technique for nanoparticles involves controlled. precipitation of nanoparticles from precursors dissolved in a solution. A micro emulsion can also be formed between two immiscible liquids, using surfactants, with the reactants isolated inside a micelle, through hydrophobic versus hydrophilic forces. The resultant nanoparticles form a colloidal suspension. Various thermodynamic factors as well as vander Waal's forces induce particle growth and agglomeration, resulting in bigger particles that settle down over time. A prerequisite in utilizing colloidal nanoparticles is that they remain stable in colloidal suspension.

Stabilization mechanism of nanoparticl.es can be categorized as
a) electrostatic stabilization: involving the creation of a double layer of adsorbed ions
over the nanoparticles resulting in a Columbic repulsion between approaching nanoparticles; or
b) Steric hindrance: achieved by adsorption of polymer molecules over the
nanoparticles. Osmotic repulsion felt by the polymer molecules due to localized increase in their
concentration when polymer coated nanoparticles approach each other, keeps them well
separated.
Chemical methods of synthesis have a further advantage of tunable surface properties of the synthesized nanoparticles, offered by the adsorbed ions (for electrostatic stabilization) or the passivating polymer (for steric hindrance). Stable colloidal nanoparticles find many futuristic applications
04. Object of invention
NanoSilver acts as a powerful, broad-spectrum antimicrobial agent. An ordinary antibiotic kills perhaps a half-dozen different disease organisms, but colloidal silver is known to be effective against over 650 disease organisms without causing any known side-effects. A normal individual excretes 98% of ionic colloidal silver in 24 hours, which accounts for part of its safety. Many essential minerals such as copper and iron are released very slowly and thus an overdose can cause long term problems. Early studies showed extremely low concentrations of 0.01-0.04 PPM of colloidal silver to be effective on hundreds of bacteria.
NanoSilver is known to kill 650 different kinds of pathogens, including bacteria, fungus and viruses in addition to many others. This is accomplished by inhibiting the enzyme which allows the oxygen metabolism in single celled microbes. It does so in minutes, safely, with no side effects and no resistant strains developed, as with antibiotics.
Humans (and other animals) absorb it so rapidly due to its small ion size that it is absorbed by the blood before it can reach the gut (antibiotics of very large molecules absorb so slowly they travel into the gut and kill your normal friendly bacteria (needed for good health in the intestines).
Early medical research indicated silver is stored in the Kupfer cells in the liver. These cells are one of the body's defense mechanisms against infection. Little mention is found in current literature of this very important added effectiveness of silver.
05. Statement of invention
Nanosilver was found effective against - Germs, Bacteria, infections, parasites, giardia, viruses, fungus and pathogens including: Allergies, Acne, Athlete's foot, Bladder infections, Inflammation, Blood Parasites, Blood-Poison, Boils, Burns, Candide Yeast Infection, Chilblains, Cholera, Conjunctivitis, Cold Sores, Colitis, Cyst-isis, Dermatitis, Diabetes caused by infection, Diphtheria, Diarrhea, Dermatitis, Dysentery, Eczema, Fibrosities, Gangrene, Gonorrhea, Herpes, HIV Virus, Impetigo, Influenza, Indigestion, Intestinal Infections, Kreatitis, Leprosy, Leukemia, Lupus, Lymphangitis, Lyme Disease, Malaria, Meningitis, Multiple Sclerosis, Neurasthenic, Parasitic Infections (oral and fungal), Pneumonia, Pleurisy, Prostatitis, Priritis Ani, Psoriasis, Purulence, Ophthalmia, Rhinitis, Rheumatism, Ring-worm, Rosacea, Scarlet Fever, Septic Conditions of the eyes, ears, mouth and throat, Sevorrhes, Shingles, Sinus Infections, Staph Infections, Strep Infections, Stomach Ulcer, Syphilis, Thyroid, Tonsillitis, Toxemia, Trachoma, Trench-Foot, Tuberculosis, Ulcers, All forms of Virus, Warts, Whooping Cough and Yeast Infections.

The value of-sliver in rr.ecT.eine, and as a purifier has beer, acknowledged for ce^:^ries, Egyptians Impiants s'.;ver places Into skuiis, with surgery. In ancient Greece and Rome, pecpie used silver containers to keep liquids fresh, When settlers moved across the American West, they would purify a container of water by putting a silver dollar in it overnight, and silver dollars were used to keep milk from spoiling.
Toward the end of the 19th Century, other medical uses for silver were developed, including the use of silver and mercury in the filling of dental cavities, and dropping a silver nitrate solution into the eyes of new-born babies to prevent blindness due to infection.
Scores of independent tests by many methods in 6 countries have shown that silver promptly kills bacteria in water and maintains water purity over long periods of time. Russian scientists, working on water recycling and purification problems for the Soviet space program have decided on silver as the best long-term sanitizing agent.
The unit will provide Shuttle crews with 32 gallons of pure water daily for all uses within the Shuttle, and for backpacks when the Astronauts work outside the vehicle in Space. Compared to earlier prototypes, the new unit weighs 90% less, needs only one third the space, doubles the production of water and simplifies the process: it eliminates the need for mixing, metering and testing water while in flight and eliminates the risk of corrosion.
06. A summary of invention
In summary, we have demonstrated that silver nanoparticles can be synthesized by simple
^wet-chemistry. By controlling the reaction conditions, nanoparticles of various sizes and shapes
can be synthesized. As an extension of the synthetic technique, various mechanisms for self
organization of the obtained nanoparticles into ID or 2D structures are being currently
pursued, that they have wide range applications in novel devices of the future.
The morphology of the resulting surfaces change with time, and depends on parameters such as starting concentration, illumination conditions, or specific silver salt used. It is remarkable that by careful control of these parameters, quite homologous films of reasonably monodisperse nanoparticles can be obtained.

APPENDIX - III
CLAIMS
What is claimed :
The claim 15 effective if one who prepared the NanoSilver by any one or the combinations of the following.


Documents:

363-che-2005 amended pages of specification 19-08-2011.pdf

363-che-2005 amended claims 19-08-2011.pdf

363-CHE-2005 ASSIGNMENT 29-03-2011.pdf

363-CHE-2005 AMENDED PAGES OF SPECIFICATION 29-03-2011.pdf

363-CHE-2005 AMENDED CLAIMS 29-03-2011.pdf

363-CHE-2005 CORRESPONDENCE OTHERS 19-08-2011.pdf

363-CHE-2005 CORRESPONDENCE OTHERS 28-07-2011.pdf

363-che-2005 examination report reply recieved 29-03-2011.pdf

363-CHE-2005 FORM-1 20-10-2011.pdf

363-che-2005 form-1 29-03-2011.pdf

363-CHE-2005 FORM-13 29-03-2011.pdf

363-che-2005 form-5 29-03-2011.pdf

363-CHE-2005 FORM-6 29-03-2011.pdf

363-CHE-2005 CORRESPONDENCE OTHERS 20-10-2011.pdf

363-che-2005-abstract.pdf

363-che-2005-claims.pdf

363-che-2005-correspondnece-others.pdf

363-che-2005-correspondnece-po.pdf

363-che-2005-description(complete).pdf

363-che-2005-description(provisional).pdf

363-che-2005-form 1.pdf

363-che-2005-form 5.pdf


Patent Number 249056
Indian Patent Application Number 363/CHE/2005
PG Journal Number 39/2011
Publication Date 30-Sep-2011
Grant Date 28-Sep-2011
Date of Filing 04-Apr-2005
Name of Patentee GURUSAMY RAJKUMAR
Applicant Address 25, T.C. SONAI KARUPPAN STREET, VIRUDHUNAGAR-626 001
Inventors:
# Inventor's Name Inventor's Address
1 KAMATCHI RAMAKRISHNAN 14-C, SATHYA SAI NAGAR, MADURAI-625 003
2 JEEVANAYAGI GANAPATHY 3/37-C, SCHOOL STREET, SOUTH KARUNGULAM, NELLAI DIST- 627 114
3 KARTHIKEYAN RAJENDRAN 31, PETTAI STREET, VIRUDHUNAGAR-626001
4 DHANASASNKAR MARIAPPAN 247, KATCHERY ROAD, VIRUDHUNAGAR-626001
5 ANANDHAN SRINIVASAN 25/10-A. 8TH STREET, PUDUNAGAR, THIRUMANGALAM-625 706,
PCT International Classification Number A61K35/78
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA