Chitosan nanoparticles phd thesis proposal

 

nanoparticles thesis

Nanoparticles are particles between 1 and nanometres (nm) in size with a surrounding interfacial layer. The interfacial layer is an integral part of nanoscale matter, fundamentally affecting all of its properties. The interfacial layer typically consists of ions, inorganic and organic molecules. PhD Thesis. IRON OXIDE NANOPARTICLES AND THEIR TOXICOLOGICAL EFFECTS: IN VIVO AND IN VITRO STUDIES. Brigitta Szalay. Department of Public Health. Faculty of . Silver nanoparticles could affect individuals Overdose of macro silver causes Argyria Safety of nano silver still unknown! Silver nanoparticles could also affect whole societies and ecosystems Silver nanoparticles can inhibit many bacteria, including “good bacteria” Silver nanoparticles can prevent photosynthesis in .


Nanoparticles Thesis


Silver nanoparticles NPs have been the subjects of researchers because of their unique properties e. A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, nanoparticles thesis, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods, nanoparticles thesis.

This review presents an overview of silver nanoparticle preparation by physical, chemical, nanoparticles thesis, and biological synthesis. The aim of this review article is, nanoparticles thesis, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of nanoparticles thesis above mentioned techniques for industries.

Nanotechnology is an important field of modern research dealing with design, synthesis, and manipulation of particle structures ranging from approximately nm. Nanoparticles NPs have wide range of applications in areas such as health care, cosmetics, food and feed, environmental health, mechanics, optics, biomedical sciences, chemical industries, electronics, space industries, drug-gene delivery, energy science, optoelectronics, catalysis, single electron transistors, light emitters, nonlinear optical devices, and photo-electrochemical applications 1nanoparticles thesis, 234nanoparticles thesis, 56.

Nanobiotechnology is a rapidly growing scientific field of producing and constructing devices. An important area nanoparticles thesis research in nanobiotechnology is the synthesis of NPs with different chemical compositions, sizes and morphologies, and controlled dispersities. Nanobiotechnology has turned up as an elementary division of contemporary nanotechnology and untied novel epoch in the fields of material science receiving global attention due to its ample applications, nanoparticles thesis.

It is a multidisciplinary approach resulting from the nanoparticles thesis use of NPs in biological systems nanoparticles thesis the disciplines of biology, biochemistry, chemistry, engineering, physics and medicine. Moreover, the nanobio-technology also serves as an imperative technique in the development nanoparticles thesis clean, nontoxic, and eco-friendly procedures for the synthesis and congregation of metal NPs having the intrinsic ability to reduce metals by specific metabolic pathways 123456.

Nowadays, there is a growing need to develop eco-friendly processes, nanoparticles thesis, which do not use toxic chemicals in the synthesis protocols, nanoparticles thesis. Green synthesis approaches include mixed-valence polyoxometalates, polysaccharides, Tollens, biological, and irradiation method which have advantages over conventional methods involving chemical agents associated with environmental toxicity.

Selection of solvent medium and selection of eco-friendly nontoxic nanoparticles thesis and stabilizing agents are nanoparticles thesis most important issues which must be considered in green synthesis of NPs.

Silver NPs are of interest because of the unique properties which can be incorporated into antimicrobial applications, biosensor materials, composite fibers, cryogenic super-conducting materials, cosmetic products, and electronic components. Some important applications of silver NPs in pharmaceutics, medicine, and dentistry are shown in Table 1. Several physical and chemical methods have been used for synthesizing and stabilizing silver NPs Table 2 78.

Some important physical, chemical and photochemical methods for synthesizing and stabilizing silver NPs. The most popular chemical approaches, including chemical reduction using a variety of organic and inorganic reducing agents, nanoparticles thesis techniques, physicochemical nanoparticles thesis, 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 and aggregation of NPs, control of crystal growth, morphology, nanoparticles thesis, size and size distribution.

Furthermore, nanoparticles thesis, 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, nanoparticles thesis, chemical, and green synthesis approaches. 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, nanoparticles thesis.

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 nanoparticles thesis 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 nanoparticles thesis 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 nanoparticles thesis temperature gradient in the vicinity of the heater surface is very steep in comparison with that of a tube nanoparticles thesis. 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 151617nanoparticles thesis, 18 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 nanoparticles thesis that the ablation efficiency for femtosecond ablation in nanoparticles thesis 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, nanoparticles thesis. 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 nanoparticles thesis time-consuming, wet-based chemical synthesis techniques.

Silver NPs possess round shape with average diameter of about 3, nanoparticles thesis. It was observed that the NPs size distribution and uniform particle dispersion remains unchanged for diluted aqueous solutions up to glycerol-to-water ratio The most common approach for synthesis of silver NPs is chemical nanoparticles thesis 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, nanoparticles thesis. Polymeric compounds such as poly vinyl alcoholpoly vinylpyrrolidonepoly ethylene glycolpoly methacrylic acidnanoparticles thesis, and 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 nanoparticles thesis rate nanoparticles thesis reaction temperature were important factors for producing uniform-sized silver NPs with a nanoparticles thesis size.

The injection of the precursor solution into a nanoparticles thesis 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 CH 3 2 to produce colloids of silver. The amide moieties, piperazine rings, nanoparticles thesis, tertiary amine groups and the hyper-branched structure in HPAMAM-N CH 3 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, nanoparticles thesis. It was reported that the formation process of these NPs could be divided into three stages: growth, incubation and Oatwald ripening stages. Moreover, the size of the colloidal silver NPs nanoparticles thesis be regulated not only by changing the heating temperature, or the nanoparticles thesis time, but also by adjusting the ratio of oleylamine to the silver precursor, nanoparticles thesis.

Silver NPs can be prepared at room temperature, by simple mixing of the corresponding metal ions with reduced polyoxometalates which serves as reducing and stabilizing nanoparticles thesis. Polyoxometalates are soluble in water and have the capability of undergoing stepwise, multielectron redox reactions without disturbing their structure. Furthermore, green chemistry-type one-step synthesis and stabilization of silver nanostructures with Mo V —Mo VI mixed-valence polyoxometalates in water at room temperature has been reported Uniform and size controllable silver Nanoparticles thesis can be synthesized using microemulsion techniques.

The NPs preparation in two-phase aqueous organic systems is based on the initial spatial separation of nanoparticles thesis metal precursor and reducing agent in two immiscible phases.

The interface between the two liquids and the intensity of inter-phase transport between two phases, which nanoparticles thesis mediated by a quaternary alkyl-ammonium salt, affect the rate of interactions between metal precursors and reducing agents. Metal clusters formed at the interface are stabilized, due to their surface being coated with stabilizer nanoparticles thesis occurring in the non-polar aqueous medium, and transferred to the organic medium by the inter-phase transporter One of the major disadvantages is the use of highly deleterious organic solvents.

Thus large amounts of surfactant and organic solvent must be separated and removed from the final product. For instance, Zhang and coworkers 39 used dodecane as oily phase a low deleterious and even nontoxic solventbut there was no need to separate the prepared silver solution from the nanoparticles thesis mixture, nanoparticles thesis. On the other hand, colloidal NPs prepared in nonaqueous media for conductive inks are well-dispersed in a low vapor pressure organic solvent, nanoparticles thesis, to readily wet the surface of polymeric substrate without any aggregation.

The advantages can also be found in the applications of metal NPs as catalysts to catalyze most organic reactions, which have been conducted in non-polar solvents. It is very important to nanoparticles thesis metal NPs to different physicochemical environments in practical applications A simple and effective method, nanoparticles thesis, UV-initiated photoreduction, has been reported for synthesis of silver NPs in the presence of citrate, polyvinylpyrrolidone, poly acrylic acidand collagen.

For instance, Huang and Yang produced silver NPs via photoreduction of silver nitrate in layered inorganic laponite clay suspensions which served as stabilizing agent for prevention of NPs aggregation.

The properties of produced NPs were studied as a function of UV irradiation time, nanoparticles thesis. Bimodal size distribution and relatively large silver NPs were obtained when irradiated under UV for 3 h. Further irradiation disintegrated the silver NPs into smaller sizes with a single distribution mode until a relatively stable size and size distribution was obtained Silver NPs nanosphere, nanowire, and dendrite have been prepared by UV irradiation photoreduction technique at room nanoparticles thesis using poly vinylalcohol as protecting and stabilizing agent.

Concentration of both poly vinylalcohol and silver nitrate played significant role in the growth of the nanorods and dendrites Sonoelectrochemistry technique utilizes the ultrasonic power primarily to manipulate the material mechanically.

Pulsed sonoelectro-chemical synthetic method involves alternating sonic and electric pulses, and electrolyte composition plays a crucial role in shape formation It was reported that silver nanospheres could be prepared by sono-electrochemical reduction using a complexing agent, nitrilotriacetate to avoid aggregation Silver NPs can be synthesized by using a variety of photoinduced or photocatalytic reduction methods.

Photochemical synthesis nanoparticles thesis a clean process which has high spatial resolution, convenience of use, and great nanoparticles thesis. Moreover, photochemical synthesis enables one to fabricate the NPs in various mediums including cells, emulsion, polymer films, nanoparticles thesis, surfactant nanoparticles thesis, glasses, etc.

Moreover, it was demonstrated that photoinduced method could be used for converting silver nanospheres into triangular silver nanocrystals nanoprisms with desired edge lengths in nm range Particle growth process was controlled using dual-beam illumination of NPs. Citrate and poly styrene sulfonate were used as stabilizing agents. The direct photo-reduction process of AgNO 3 in the presence of sodium citrate NaCit was carried out with different light sources UV, white, blue, cyan, green and orange at room temperature.

Moreover, Ghosh and colleagues 48 reported a simple and reproducible UV photo-activation method for the preparation of stable silver NPs in aqueous Triton X TX Furthermore, surfactant solution helps to carry out the process of NPs growth in the diffusion controlled way by decreasing the diffusion or mass transfer co-efficient of the system. It also helps to improve the NPs size distributions by increasing the surface tension at the solvent-NPs interface.

CMCTS, a water-soluble and biocompatible chitosan derivative, served simultaneously as a reducing agent for silver cation and a stabilizing agent for the silver NPs. The diameter range of produced silver NPs was 2—8 nm, and they can be dispersed stably in the alkaline CMCTS solution for more than 6 months.

 

Synthesis of silver nanoparticles: chemical, physical and biological methods

 

nanoparticles thesis

 

Nanoparticles Tyler Paul Bennett University of New Hampshire, Durham Follow this and additional works at:debranddi.cf This Thesis is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has beenAuthor: Tyler Paul Bennett. Nanoparticles are particles between 1 and nanometres (nm) in size with a surrounding interfacial layer. The interfacial layer is an integral part of nanoscale matter, fundamentally affecting all of its properties. The interfacial layer typically consists of ions, inorganic and organic molecules. PhD Thesis. IRON OXIDE NANOPARTICLES AND THEIR TOXICOLOGICAL EFFECTS: IN VIVO AND IN VITRO STUDIES. Brigitta Szalay. Department of Public Health. Faculty of .