Synthesis of silver nanoparticles

05013


Introduction
As of October 2023, the world population exceeded 8 billion 67 million people.About 60 percent of the world's population lives in Asia, 17 percent in Africa, 9.6 percent in Europe, 8.4 percent in Latin America, 5 percent in North America and 0.5 percent in Oceania.It is predicted that by 2050, approximately 56% of the world's population will live in Asia, 26% in Africa, 8.0% in Latin America, 7.5% in Europe, 4.5% in North America and 0.6% in Oceania .If population growth dynamics do not change dramatically, the 9 billion mark will be surpassed around 2042.According to the State Statistics Committee of the Republic of Uzbekistan, as of December 9, 2022, the population of Uzbekistan was 36,001,364 people [1].
Three crises: the wars Russia-Ukraine, Israel-Hamas, the ongoing Covid-19 pandemic and dramatic global climate change are intensifying a fourth crisis for the world's growing population -the risk of global famine.It should be noted that food prices are rising amid other serious problems in the global economy.Inflation is rising and the COVID-19 pandemic continues to disrupt supply chains, while climate change is wreaking havoc in many of the world's agricultural regions, with droughts, floods, heatwaves and wildfires threatening to be unleashed.In addition to disrupting food production and supply systems, war also damages global food production.Rising energy prices affect fertilizer production, which ultimately increases food prices.Russia, Belarus and Ukraine are the largest producers of potash fertilizer, and wartime sanctions created shortages and sharply increased fertilizer prices.The combination of these factors is likely to keep food prices high next year due to lower fertilizer use, lower yields and higher food production costs.

Literature review
Human life is closely connected with the plant world.Plants are the main source of food for the animal world, including humanity.Plants clothe and heal humanity, saturate the air with oxygen, purify the atmosphere, and serve as a source of raw materials for the production of building materials, cellulose products and other products.In modern conditions, one of the pressing issues is obtaining a large and healthy harvest from plants to feed humanity.Pests, diseases, weeds and other harmful factors significantly reduce or destroy plants and their productivity.To eliminate these harmful effects, scientists are constantly working on ways to protect plants.
To protect plants, agrotechnical, physical-mechanical, chemical, biological and complex methods are used.Crop rotation, irrigation optimization, weather and weed risk management, and pest and disease control are also important to protect plants from pests and diseases.Plant protection measures save energy and money.According to the Food and Agriculture Committee of the United Nations, if plant protection is stopped, about 40 percent of crops will be lost to pests and diseases.
Many plant viral diseases are transmitted by insects, so insect control is considered related to the control of viral diseases [2,3].
In order for plants to grow effectively, it is necessary to use methods that help protect them from the negative effects of external factors.In addition, the methods used must not only be effective, but also environmentally beneficial.To do this, it is necessary to use modern plant protection products.Chemical plant protection products can be divided into the following groups: Fungicides are pesticides used to control fungi and their spores that act primarily by damaging fungal cell membranes or interfering with energy production in fungal cells; Herbicides are a group of pesticides that selectively or non-selectively attack weeds of agricultural crops.Weeds slow down the growth of cultivated plants.
Insecticides are chemicals used to control insects.They are classified according to their structure and mode of action.A large number of insecticides attack the nervous system of insects or act as growth regulators or endotoxins.For example, paradichlorobenzene is used as an insect and fungal control agent.Adjuvants are additives used in pesticides to increase their effectiveness.Plants, like mushrooms, have a waxy surface.This makes it difficult for pesticides to achieve their intended purpose.Bioregulators are substances that stimulate the natural physiological processes of plants, dormancy, seed germination, leaf aging, cell division, cell growth and differentiation.They have a protective effect against all biotic and abiotic stresses.
Since ancient times, it has been known that silver has antibacterial properties.Silver was used in medicine, water and air purification, food, cosmetics, clothing and many household items.Silver nanoparticles may exhibit additional antimicrobial properties that ionic silver does not have.Silver nanoparticles are small in size and have a high surface to volume ratio.Silver nanoparticles have high surface energy, making them ideal for immobilization on textiles.In addition, silver nanoparticles have an antibacterial effect on treated fabrics.This feature makes them very useful as they help prevent the growth of pathogens.Nanosilver particles present in the thread modified with silver ions have antimicrobial, bactericidal and fungicidal effects.For example, they can be used in food, medical devices and household appliances.In addition, threads modified with silver ions are an ideal disinfectant fabric.Silver ions act on cell membrane proteins, directly destroy bacterial cell membranes and bind to oxygen exchange enzymes (-SH).Prevents bacteria from absorbing essential nutrients such as uracil and amino acids, thereby inhibiting their growth.This sterilization mechanism kills most bacteria, fungi and other microorganisms and renders them unable to reproduce into the next generation.The production of colloidal silver nanoparticles (AgNP) involves various methods including chemical reduction, electrochemical methods and green synthesis using plant extracts [3,4].
The biostimulant colloidal silver has emerged as a promising solution in agriculture due to its potential as a plant growth promoter and pest control agent.The biostimulant colloidal silver has received much attention in agriculture due to its potential as a plant growth promoter and pest control agent.The addition of biostimulants such as humic acid, seaweed extract and amino acids enhances the properties and stimulates plant growth of the effect of colloidal silver.The combined use of biostimulants with colloidal silver nanoparticles causes a synergistic effect.As a result, plant growth improves, productivity increases and the quality of agricultural products improves [3,4].
The biostimulant colloidal silver exhibits unique properties such as antimicrobial activity, enhanced nutrient absorption, enhanced photosynthesis and increased plant resistance to biotic and abiotic stress.The biostimulator colloidal silver has a number of unique properties.Its activity against fungi, microbes, bacterial and viral pathogens has been shown [4].
Increases nutrient uptake by plants, improves nutrition and overall health.In addition, the biostimulator colloidal silver enhances plant photosynthesis and increases plant resistance to biotic and abiotic stresses [4][5][6].
Colloidal silver is very convenient to use with biostimulants in agriculture.Depending on their physicochemical properties, they can be applied in a variety of ways, including seed treatments, foliar sprays, root feeding, irrigation and hydroponic systems.These application methods provide effective and targeted delivery of nanoparticles and biostimulants to plants [6].
The production and use of biostimulants of colloidal silver preparations has great potential in agriculture.Colloidal silver biostimulants can lead to sustainable increases in agricultural yields.Employees of the Namangan Engineering and Technology Institute conduct scientific research on the synthesis of nanosilver compounds and systems that increase plant resistance to various diseases and protect them [7][8][9].Silver nitrate and reducing agents: glucose, sodium citrate, hydrazine and stabilizers are used to obtain stable colloidal systems of silver nanoparticles.Local raw materials are mainly used as stabilizers: starch (corn and potato), dextrin, protein compounds (gelatin and albumin), carboxymethylcellulose, polyvinylprolidone, polyvinyl alcohol and polyvinyl acetate, hydroxyethylcellulose, sodium dodecyl sulfate.Most are cheap and can be purchased at local grocers.This, in turn, leads to cost efficiency.

Research methodology
To synthesize silver nanoparticles (AgNP), solutions containing silver nitrate as the main substance, glucose, sodium citrate and hydrazine as reducing agents, and polyvinylprolidone (PVP), polyvinyl alcohol (PVAl) and polyvinyl acetate (PVAc) as stabilizers were used.The reactions were carried out at room temperature by adding equal volumes of reducing solutions to the solution of stabilizers and a mixture of silver nitrate with constant stirring of the solutions.

Results and discussion
Initially, solutions of stabilizers were prepared at a temperature of 20°C -5% PVP, PVAl and 1% PVAc.Then a solution of silver nitrate with a concentration of 500 mg/ml was prepared.0.1 M solutions of sodium citrate, hydrazine and glucose were prepared as reducing agents.12 different samples were prepared by adding stabilizers and silver nitrate solutions to a mixture obtained by adding equal volumes of reducing solutions with constant stirring.
In the first experiment, 1% PVAc solution, 5% PVP and PVAl solutions were used as stabilizers.Nanosilver systems were obtained by reducing solutions of silver nitrate in the presence of glucose (Table 1 In the second experiment, 5% solutions of PVP and PVA and a 1% solution of PVA were used as stabilizers.Parameters such as silver ion concentration, solution composition, and reaction time mainly affect the size, shape, and morphology of AgNP.

Conclusion
Silver nanoparticles were synthesized from aqueous solutions at room temperature by chemical reduction.Factors influencing the stability of synthesized silver nanoparticles have been studied.The decrease in the dispersity of silver nanoparticles is explained mainly by an increase in color intensity.Silver nanoparticles in systems obtained based on favorable factors remained stable for 30 days and did not settle.During the synthesis of silver nanoparticles, it was shown that by controlling the reaction conditions it is possible to obtain nanoparticles of various shapes and sizes.The shape and size of silver nanoparticles depend on the concentration of the silver nitrate solution, the nature of the stabilizer and reducing agent, and temperature.

Table 2 .
Nanosilver systems obtained in the presence of sodium citrate and various stabilizers that reduce AgNO3 at 20°C.

Table 4 .
Nanosilver systems obtained in the presence of various stabilizers without reduction of AgNO3 at 20°C.