Silver nanoparticles (AgNPs) are silver particles with sizes from 1 to 100 nanometers. They are physical, chemical and biologically special particles, unlike bulk silver, due to the fact that they have a very large surface area-to-volume ratio and quantum size effects. AgNPs have become very popular in medical, electronic and environmental science because of their antimicrobial action, optical properties and reactivity. Their molecular-level reactivity with biological and chemical systems opens up a huge variety of applications.
AgNPs need to be characterized in order to discover their properties and modify them for particular applications. We can compare AgNPs size, shape, surface and stability by several different methods:
1. Transmission Electron Microscopy (TEM): Gets ultra-high-resolution image for size and shape of AgNPs.
2. Dynamic Light Scattering (DLS): Determines hydrodynamic size and zeta potential of suspended nanoparticles for stabilization.
3. UV-Vis Spectroscopy: To detect the signature surface plasmon resonance (SPR) peak of AgNPs (400-450 nm) as a measure of optical quality.
4. XRD: Enables AgNPs to be confirmed as crystals.
5. Fourier Transform Infrared Spectroscopy (FTIR): Probes surface functional groups and interactions with stabilizing agents.
6. Energy Dispersive X-ray Spectroscopy (EDX): Determines AgNP elemental composition.
All of these approaches together provide a full picture of AgNPs, and they can be synthesized and used reproducibly.
Chemical synthesis of AgNPs is usually performed by reducing silver ions (Ag+) to elemental silver using reducing and stabilizing agents. Common methods include:
Chemical reduction: Chemical reduction is an easy and common way to produce AgNPs. They reduce Ag+ to Ag0 using reducing agents like sodium borohydride (NaBH4) or citrate. Stabilizers such as polyvinyl alcohol (PVA) or polyethylene glycol (PEG) are added to stop the aggregation and maintain even distribution of the nanoparticles. This is the most popular because it is relatively simple and reproducible, suitable for large scale manufacturing (though small particle size can be difficult to control).
Fig.1 Chemical scheme of silver nanoparticle synthesis. (Rac-Rumijowska, Olga, et al., 2017)
Sol-Gel Method: The sol-gel method involves the transformation of a colloidal solution into a gel-like network that serves as a precursor for AgNP formation. By manipulating parameters such as pH, temperature, and precursor concentration, researchers can achieve precise control over nanoparticle size and morphology. This method is advantageous for producing highly uniform and stable AgNPs, but it may require longer processing times and careful optimization of conditions.
Microemulsion Technique: The microemulsion technique uses water-in-oil emulsions as nanoreactors for the controlled synthesis of AgNPs. In this approach, the aqueous phase contains silver salts, while the oil phase stabilizes the system. Surfactants maintain the emulsion's stability, allowing precise control over nanoparticle nucleation and growth. This method is highly efficient for producing monodisperse particles, but the use of surfactants may introduce additional purification steps.
Photochemical Synthesis: Photochemical synthesis leverages light energy to reduce silver ions in the presence of photoactive compounds. This environmentally friendly method avoids harsh chemical reducing agents, relying instead on light-induced reactions to form AgNPs. It offers precise control over reaction kinetics and nanoparticle properties by varying light intensity and wavelength. However, the method requires specialized equipment and may not be ideal for large-scale production.
Green Synthesis: Green synthesis employs natural reducing and capping agents, such as plant extracts, microorganisms, or biomolecules, to produce AgNPs in an eco-friendly manner. This approach reduces environmental impact and enhances biocompatibility, making it particularly attractive for biomedical applications. While green synthesis is sustainable and cost-effective, achieving consistent particle size and purity can be challenging, necessitating rigorous optimization.
Advantages
Disadvantages
AgNPs are employed in various fields due to their multifunctional properties:
Medical Applications: Silver nanoparticles are widely used in wound dressings, medical device coatings, and disinfectants for their antimicrobial properties. Functionalized AgNPs also serve as efficient carriers in targeted drug delivery and improve the sensitivity of biosensors for detecting biomolecules.
Environmental Applications: AgNPs play a crucial role in water treatment systems by effectively removing contaminants and pathogens, contributing to cleaner and safer water resources.
Electronics: With excellent electrical conductivity, AgNPs are integral to conductive inks and flexible electronics, enabling advancements in wearable devices and next-generation technologies.
Textiles: Silver nanoparticles impart long-lasting antimicrobial properties to fabrics, enhancing hygiene and extending the usability of textiles in various applications, including healthcare and sports.
Food Industry: AgNPs act as preservatives and are incorporated into packaging materials to extend shelf life and maintain the quality of food products during storage and transportation.
AgNPs have shown promise in cancer research and treatment due to their unique properties:
Cytotoxic Effects on Cancer Cells
AgNPs induce oxidative stress and damage cellular components like DNA, triggering apoptosis in cancer cells. When optimized, they selectively target cancer cells, sparing normal cells, enhancing therapeutic efficacy.
Drug Delivery Systems
Functionalized AgNPs can efficiently deliver chemotherapeutic agents directly to tumor sites, minimizing systemic toxicity and improving treatment outcomes.
Photothermal Therapy
AgNPs harness their strong surface plasmon resonance (SPR) to convert light energy into heat, effectively inducing thermal damage and killing cancer cells.
Imaging and Diagnostics
AgNPs enhance imaging techniques, such as fluorescence and surface-enhanced Raman spectroscopy (SERS), facilitating early detection and accurate diagnosis of cancer.
While AgNPs hold immense potential, further research is needed to address challenges related to their biocompatibility, toxicity, and large-scale production. By overcoming these hurdles, AgNPs could become a cornerstone in advancing cancer therapies and other biomedical applications.
BOC Sciences offers a wide range of silver nanoparticle customization services, including different types, surface finishes, and sizes, to meet a variety of research and application needs. Below is the list of products we can provide, if you have more needs, please contact us to customize the synthesis of your silver nanoparticles.
| Product Type | Available Sizes | Price |
| Silver Nanospheres | 2 nm, 10 nm, 20 nm, 30 nm, 60 nm, 100 nm, 500 nm | Inquiry |
| Silver Nanoplates | 2 nm, 10 nm, 20 nm, 30 nm, 60 nm, 100 nm, 500 nm | Inquiry |
| Silver Nanocubes | 2 nm, 10 nm, 20 nm, 30 nm, 60 nm, 100 nm, 500 nm | Inquiry |
| Silica-Shelled Silver Nanoparticles | 2 nm, 10 nm, 20 nm, 30 nm, 60 nm, 100 nm, 500 nm | Inquiry |
| Silver-Shelled Gold Nanospheres | 2 nm, 10 nm, 20 nm, 30 nm, 60 nm, 100 nm, 500 nm | Inquiry |
| Modification Type | Price |
| Chitosan Silver Nanoparticles | Inquiry |
| Citrate-Capped Silver Nanoparticles | Inquiry |
| Curcumin Silver Nanoparticles | Inquiry |
Silver nanoparticles are made by reducing silver nitrate (AgNO3) with agents like sodium borohydride, citrate, or plant extracts, forming stable nanoparticle dispersions.
Silver nanoparticles release silver ions and generate reactive oxygen species, disrupting bacterial membranes, proteins, and DNA, leading to cell death.
Nanoparticle concentration is calculated using UV-Vis absorbance, particle size, and molar extinction coefficient, or by estimating total silver mass and particle volume.
Silver nanoparticles are used in antimicrobial coatings, wound dressings, water purification, food packaging, and medical devices due to their strong antibacterial properties.
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