Modified from definitions of nanoparticle and nanogel in [refs.
Open in a separate window The most popular chemical approaches, including chemical reduction using a variety of organic and inorganic reducing agents, electrochemical techniques, physicochemical reduction, and radiolysis are widely used for the synthesis of silver NPs.
Most of these methods are still in development stage and the experienced problems are the stability Synthesis of silver nanaoparticles aggregation of NPs, control of crystal growth, morphology, size and size distribution.
Furthermore, extraction and purification of produced NPs for further applications are still important issues 910 This review article presents an overview of silver nanoparticle preparation by physical, chemical, and green synthesis approaches.
Synthesis of silver NPs Physical methods Evaporation-condensation and laser ablation are the most important physical approaches. The absence of solvent contamination in the prepared thin films and the uniformity of NPs distribution are the advantages of physical synthesis methods in comparison with chemical processes.
Physical synthesis of silver NPs using a tube furnace at atmospheric pressure has some disadvantages, for example, tube furnace occupies a large space, consumes a great amount of energy while raising the environmental temperature around the source material, and requires a lot of time to achieve thermal stability.
Moreover, a typical tube furnace requires power consumption of more than several kilowatts and a preheating time of several tens of minutes to reach a stable operating temperature 12 It was demonstrated that silver NPs could be synthesized via a small ceramic heater with a local heating area The small ceramic heater was used to evaporate source materials.
The evaporated vapor can cool at a suitable rapid rate, because the temperature gradient in the vicinity of the heater surface is very steep in comparison with that of a tube furnace.
This makes possible the formation of small NPs in high concentration. The particle generation is very stable, because the temperature of the heater surface does not fluctuate with time. This physical method can be useful as a nanoparticle generator for long-term experiments for inhalation toxicity studies, and as a calibration device for nanoparticle measurement equipment The results showed that the geometric mean diameter, the geometric standard deviation and the total number concentration of NPs increase with heater surface temperature.
Spherical NPs without agglomeration were observed, even at high concentration with high heater surface temperature.
The geometric mean diameter and the geometric standard deviation of silver NPs were in the range of 6. Silver NPs could be synthesized by laser ablation of metallic bulk materials in solution 15161718 The ablation efficiency and the characteristics of produced nano-silver particles depend upon many parameters, including the wavelength of the laser impinging the metallic target, the duration of the laser pulses in the femto- pico- and nanosecond regimethe laser fluence, the ablation time duration and the effective liquid medium, with or without the presence of surfactants 202122 One important advantage of laser ablation technique compared to other methods for production of metal colloids is the absence of chemical reagents in solutions.
Therefore, pure and uncontaminated metal colloids for further applications can be prepared by this technique Silver nanospheroids nm were prepared by laser ablation in water with femtosecond laser pulses at nm The formation efficiency and the size of colloidal particles were compared with those of colloidal particles prepared by nanosecond laser pulses.
As a result, the formation efficiency for femtosecond pulses was significantly lower than that for nanosecond pulses. The size of colloids prepared by femtosecond pulses were less dispersed than that of colloids prepared by nanosecond pulses.
Furthermore, it was found that the ablation efficiency for femtosecond ablation in water was lower than that in air, while in the case of nanosecond pulses, the ablation efficiency was similar in both water and air.
Tien and coworkers 26 used the arc discharge method to fabricate silver NPs suspension in deionized water with no added surfactants. In this synthesis, silver wires Gredmann, Siegel and colleagues 27 demonstrated the synthesis of silver NPs by direct metal sputtering into the liquid medium.
The method, combining physical deposition of metal into propane-1,2,3-triol glycerolprovides an interesting alternative to time-consuming, wet-based chemical synthesis techniques. Silver NPs possess round shape with average diameter of about 3.
It was observed that the NPs size distribution and uniform particle dispersion remains unchanged for diluted aqueous solutions up to glycerol-to-water ratio 1: Chemical methods Chemical reduction The most common approach for synthesis of silver NPs is chemical reduction by organic and inorganic reducing agents.
These clusters eventually lead to the formation of metallic colloidal silver particles 2829 It is important to use protective agents to stabilize dispersive NPs during the course of metal nanoparticle preparation, and protect the NPs that can be absorbed on or bind onto nanoparticle surfaces, avoiding their agglomeration The presence of surfactants comprising functionalities e.
Polymeric compounds such as poly vinyl alcoholpoly vinylpyrrolidonepoly ethylene glycolpoly methacrylic acidand polymethylmethacrylate have been reported to be the effective protective agents to stabilize NPs.
They reported that small changes in synthetic factors lead to dramatic modifications in nanoparticle structure, average size, size distribution width, stability and self-assembly patterns.
Kim and colleagues 33 reported synthesis of spherical silver NPs with a controllable size and high monodispersity using the polyol process and a modified precursor injection technique. In the precursor injection method, the injection rate and reaction temperature were important factors for producing uniform-sized silver NPs with a reduced size.
The injection of the precursor solution into a hot solution is an effective means to induce rapid nucleation in a short period of time, ensuring the fabrication of silver NPs with a smaller size and a narrower size distribution. Zhang and coworkers 34 used a hyper branched poly methylene bisacrylamide aminoethyl piperazine with terminal dimethylamine groups HPAMAM-N CH3 2 to produce colloids of silver.
The amide moieties, piperazine rings, tertiary amine groups and the hyper-branched structure in HPAMAM-N CH3 2 are important to its effective stabilizing and reducing abilities. Chen and colleagues 35 have shown the formation of monodispersed silver NPs using simple oleylamine-liquid paraffin system.
It was reported that the formation process of these NPs could be divided into three stages:Without the silver nanoparticle catalyst, virtually no reaction occurs between sodium borohydride and the various dyes: methylene blue, eosin, and rose bengal.
Mesoporous aerogel – selective oxidation of benzene. Silver nanoparticles supported on aerogel are advantageous due to the higher number of active sites. Abstract—Silver nanoparticles were prepared by chemical Synthesis of silver nanoparticles by chemical reduction method and their antibacterial activity For the synthesis of silver nanoparticles, silver nitrate solution (from 1,0 mM to .
Conclusion: This is the first report on the synthesis of silver nanoparticles using D.
bulbifera tuber extract followed by an estimation of its synergistic potential for enhancement of the antibacterial activity of broad spectrum antimicrobial agents. Synthesis of silver nanoparticles Physical approach.
In physical processes, metal nanoparticles are generally synthesized by evaporation–condensation, which could be carried out using a tube furnace at atmospheric pressure. The source material within a boat centered at the furnace is vaporized into a carrier gas.
Keywords: Nanoparticle synthesis, Silver nanoparticles, Physical synthesis, Chemical synthesis, Biological synthesis INTRODUCTION Nanotechnology is an important field of modern research dealing with design, synthesis, and manipulation of particle structures ranging from approximately nm. Collaborative Lab Model Provides synthesized nanoparticles Students go to biology lab to explain synthesis process Chemistry Lab: Synthesizes silver.