Methods for producing silver nanoparticles
Inventors
Raghuraman, Kannan • Katti, Kattesh K.
Assignees
University of Missouri System • University of Missouri St Louis
Publication Number
US-9005663-B2
Publication Date
2015-04-14
Expiration Date
2024-08-31
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Abstract
An exemplary embodiment of the invention is a method for making silver nanoparticles, and includes steps of reacting a silver salt with a phosphene amino acid to make silver nanoparticles. Exemplary phosphene amino acids include trimers, with a particular example being a trimeric amino acid conjugate containing one phosphene group. In an exemplary method of the invention, the silver nanoparticles may be produced in timer periods of less than about 30 minutes, and at temperatures of less than about 40° C. Other methods of the invention are directed to methods for stabilizing silver nanoparticles.
Core Innovation
The invention provides methods for producing silver nanoparticles by reacting a silver salt with a phosphine amino acid. A preferred embodiment utilizes a trimeric amino acid conjugate containing one phosphine group, such as TAAC (trimeric alanine attached to a phosphorous center). The process involves combining the silver salt (such as AgNO3), a phosphine amino acid, starch, and a suitable solvent such as water, resulting in the rapid formation of silver nanoparticles under mild conditions.
These methods address critical challenges in prior art, which relied on hazardous chemicals like hydrazine and sodium borohydride, requiring complex handling and posing safety risks. Existing techniques also necessitated high temperatures (60–80°C), long reaction times (up to 20 hours), and yielded broad nanoparticle size distributions and unstable products. This invention avoids these disadvantages by using environmentally and biologically benign reactants, producing nanoparticles quickly (as little as 5 minutes) at low temperature (often room temperature), and providing controlled size distributions.
Besides synthesis, the invention includes methods for stabilizing and storing silver nanoparticles using phosphine amino acids, such as TAAC or its oxide, which allows prolonged storage without significant agglomeration. These improvements facilitate safer, more efficient, and versatile production and storage of silver nanoparticles for a variety of uses.
Claims Coverage
The patent includes five independent claims, each defining a key inventive feature pertaining to methods of producing and stabilizing silver nanoparticles.
Room-temperature production of silver nanoparticles using phosphine amino acids and starch
A method comprising: - Providing a silver salt - Combining the silver salt with starch and at least one solvent - Providing a phosphine amino acid including three alanines bound to a phosphorous center via a NCH2 bond - Reacting these to form silver nanoparticles The method achieves rapid conversion under mild (room temperature or lower) conditions.
Use of a defined phosphine amino acid as a reactant for silver nanoparticle synthesis
A method where: - The phosphine amino acid used has a specific structure consisting of three alanines bound to a phosphorous center via a NCH2 bond and specific chemical formula - The method involves providing both the silver salt and the structured phosphine amino acid as reactants for nanoparticle synthesis
Stepwise dissolution of starch and phosphine amino acid conjugate prior to silver salt combination
A method comprising: - Dissolving starch in water to form a starch solution - Dissolving a trimeric amino acid conjugate (containing three alanines bound to a phosphorous center via a NCH2 bond) in water to form a phosphine amino acid solution This enables controlled formation of silver nanoparticles upon mixing with the silver salt.
Stabilization of silver nanoparticles using a defined phosphine amino acid
A method comprising: - Providing silver nanoparticles - Providing a phosphine amino acid including three alanines bound to a phosphorous center via a NCH2 bond - The phosphine amino acid acts as the stabilizing agent, allowing storage without agglomeration
The inventive features are centered on specific, mild methods for producing and stabilizing silver nanoparticles using phosphine amino acids, controlled reactant sequences, and defined chemical structures, all enabling rapid, safe, and stable nanoparticle production.
Stated Advantages
Silver nanoparticle synthesis proceeds rapidly (as little as 5 minutes) and at low temperatures, often at room temperature.
The method achieves high conversion rates—at least about 70%, and up to about 98% of silver salt converted to nanoparticles.
Environmentally and biologically benign materials are used, eliminating the need for hazardous, difficult-to-store chemicals.
Nanoparticle size distribution is relatively uniform and can be tuned by adjusting reactant concentrations.
Silver nanoparticles remain stable for extended storage periods (weeks to months) without significant agglomeration.
The method is suited for both in-vitro and in-vivo use due to benign reactants and mild conditions.
Simple procedures and non-hazardous materials make the process practical for large-scale commercial or field deployment.
Documented Applications
Production of silver nanoparticles as biosensors and medical markers for use in diagnostics and medical research.
Manufacture of silver nanoparticles for use in smart windows, rewritable electronic paper, electronic panel displays, and memory components.
In-vitro and in-vivo formation of silver nanoparticles, including synthesis directly in living organisms such as mammals or humans.
Production of silver nanoparticles in the field for military or commercial applications, enabling on-site synthesis by users such as soldiers or technicians.
Large-scale commercial production and storage of uniform, stable silver nanoparticles.
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