Preparation of silver iodide nanoparticles using laser ablation in liquid for antibacterial applications

In this study, the authors reported the first synthesis process of silver iodide (AgI) nanoparticles (NPs) by pulsed laser ablation of the AgI target in deionised distilled water. The optical and structural properties of AgI NPs were investigated by using UV–vis absorption, X‐ray diffraction, scanning electron microscope (SEM), energy dispersive X‐ray, Fourier transform infrared spectroscopy, and transmission electron microscope (TEM). The optical data showed the presence of plasmon peak at 434 nm and the optical bandgap was found to be 2.6 eV at room temperature. SEM results confirm the agglomeration and aggregation of synthesised AgI NPs. TEM investigation showed that AgI NPs have a spherical shape and the average particle size was around 20 nm. The particle size distribution was the Gaussian type. The results showed that the synthesised AgI NPs have antibacterial activities against both bacterial strains and the activities were more potent against gram‐negative bacteria.Inspec keywords: antibacterial activity, nanoparticles, X‐ray chemical analysis, particle size, transmission electron microscopy, X‐ray diffraction, nanofabrication, scanning electron microscopy, visible spectra, ultraviolet spectra, silver compounds, pulsed laser deposition, Fourier transform infrared spectra, optical constants, energy gap, aggregationOther keywords: synthesis process, pulsed laser ablation, AgI target, deionised distilled water, optical properties, structural properties, UV–vis absorption, X‐ray diffraction, transmission electron microscope, optical data, optical bandgap, antibacterial activities, silver iodide nanoparticles, energy dispersive X‐ray analysis, SEM, wavelength 434.0 nm, temperature 293 K to 298 K, AgI     

Preparation and characterization of dendritic silver nanoparticles

Dendritic silver nanoparticles have been prepared by a soft solution technique from the aqueous solution of silver nitrate and poly (vinyl pyrrolidone) (PVP) in the presence of ethanol used as a reducing agent. The resultant silver nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive analyses of X-ray (EDX), and UV-Visible absorption spectroscopy. It was found that the well-defined dendritic silver nanoparticles which had the length 0.5–1 m and the width of 100–200 nm.     

纳米纤维素/银纳米粒子的制备和表征

以纳米纤维素(NCC)为分散剂,硼氢化钠为还原剂还原硝酸银,化学还原法制备纳米纤维素/银纳米粒子。m(Ag)/m(NCC)=5%制备的纳米纤维素/银纳米粒子,X射线衍射分析结果表明,纳米纤维素/银纳米粒子中NCC和银纳米粒子相互混合并未改变各自的晶型,纳米纤维素/银纳米粒子中银纳米粒子的晶粒尺寸为11.87nm,与透射电子显微镜(TEM)所测银纳米粒子直径(10nm)相近;热重分析结果表明,纳米纤维素/银纳米粒子的热稳定性较纳米纤维素稍有下降。透射电子显微镜(TEM)分析、紫外光谱分析、固含量分析、机理分析和抑菌活性分析结果表明,m(Ag)/m(NCC)=3%时制备的纳米纤维素/银纳米粒子对大肠杆菌和金黄色葡萄球菌均有抑制作用,且银纳米粒子在纳米纤维素/银纳米粒子中分散较均匀。     

Synthesis and optical characterization of copper nanoparticles prepared by laser ablation

The remarkable size-tunable properties of nanoparticles (NPs) make them a hot research topic with applications in a wide range of fields. Hence, copper (Cu) colloidal NPs were prepared using laser ablation (Nd:YAG, 1064 nm, 7 ns, 10 Hz, 6000 pulses) of a copper metal plate at different laser fluences (LFs) in the range of 1–2.5 J cm^?2 in ethylene glycol (EG), at room temperature. Analysis of NPs was carried using different independent techniques such as ultraviolet–visible (UV–vis) spectroscopy; transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. TEM analysis showed that the NPs were spherical with a bimodal distribution and an average particle size of 5 and 16 nm influence of 1.2 J cms^?2, and 9 and 22 nm at 2 J cm^?2. The UV–vis spectra of colloidal NPs revealed the maximum absorbance at around 584 nm, indicating the formation of Cu NPs, which supported using FTIR spectra. Furthermore, the absorption spectra confirmed the metallic nature of Cu NPs. FTIR spectroscopy was utilized to verify information about the NPs surface state and chemical bonds constructed in the atom groups apparent on their surface.     

Preparation of colloidal cadmium selenide nanoparticles by pulsed laser ablation in methanol and toluene

Colloidal spherical nanoparticles (NPs) of cadmium selenide (CdSe) have been prepared by laser ablation of cadmium target in methanol and toluene solutions. The properties of CdSe nanoparticles ablated in methanol and toluene were investigated and compared. The morphology and structure of synthesised CdSe NPs were analyzed by X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscope (TEM). XRD investigation revealed that the nanoparticles are crystalline and have hexagonal structure. Optical absorption showed that the value of optical energy gap of ablated CdSe nanoparticles depends on the solution type. TEM measurements showed that CdSe NPs with diameters ranging from 25 to 35 nm were synthesised in methanol while, the nanoparticles ablated in toluene have diameters in the range of (40–50) nm.     

Synthesis and characterization of phospholipid-functionalized silver nanoparticles

Functionalizations of silver nanoparticles (AgNPs) by phospholipids (PLs) have been manifested well by means of covalent connection between AgNPs with PLs. After functionalization, the attached PLs can self-assemble into bilayer structures on the surfaces of AgNPs. TEM displays the images of pure AgNPs and functionalized AgNPs with certain thickness of the phospholipid bilayers, as a result of chemical connection existing in AgNPs-PL conjugates. UV-vis and IR spectra confirm the strong Ag-S interaction between silver and sulfur produced during the reactions. This new modification method for AgNPs offers a good opportunity to functionalize nanoparticles with biological activity.     

Synthesis and characterization of titania-coated silver nanoparticles

Silver particles of 70 +/- 10 nm mean diameter were coated with uniform layers of amorphous titania by the hydrolysis and polycondensation process using titanium(IV) n-butoxide in aqueous solution. Because of the large dielectric function of titania, a shift to the longer wavelengths was observed for the plasmon resonance maximum of coated silver nanoparticles. By changing the alkoxide to particles ratio in the reaction mixture, thickness ranging from 5 to 20 nm was obtained. Hydrothermal treatment performed on coated particles at 350 degrees C for 4 h converted amorphous titania to the anatase crystalline form. The anatase form was confirmed by X-ray powder diffraction. More red shift of the plasmon resonance was observed for the hydrothermally treated samples compared with the particles coated with amorphous titania.     

Investigation of laser ablation loading of polymers

For polyethylene and polytetrafluoroethylene targets irradiated by laser pulses with energy densities within 100–1000 J/cm², the ablation loading coefficients amount to 8–11% and 8–10%, respectively. These values satisfactorily agree with theoretical estimates of the ablation loading, which are about 6–8%.     

Metal nanoparticles generated by laser ablation

We study a new method for producing ultrafine metal particles (nanopartides) that employs Laser Ablation of Microparticles (LAM). Pulsed excimer laser radiation at 248 nm wavelength was used to ablate ~2 μm feedstock of silver, gold, andpermalloy (Ni₈₁%:Fe_19%) under both normal atmospheric conditions and in other gases and pressures. A model for nanoparticle formation by LAM is proposed that includes plasma breakdown and shock-wave propagation through the initial microparticle. Behind the shock a large fraction of the original microparticle mass is converted to nanoparticles that diffuse to silicon substrates and TEM grids for collection and analysis. Nanoparticle morphologies are spherical except for gold nanoparticles >100 nm that are generally cubes. Electron micrographs of the samples were analyzed by computer-aided image processing to determine the effect of irradiation conditions on the nanoparticle size distribution. The results showed that mean particle diameters were normally in the range from 10 to 100 nm and that the particle size distributions were generally log-normal, with dispersion (diameter/standard deviation) ranging from 0.2 to 0.5. For metallic microparticle feedstock, the mean size of the produced nanoparticles generally increased with increasing laser fluence and were smallest for fluences not too far above the breakdown threshold.     

Directly ultraviolet photochemical deposition of silver nanoparticles on silica spheres: Preparation and characterization

A simple method was developed to directly deposit silver nanoparticles on the surface of silica spheres. The photochemical reduction was carried out by ultraviolet irradiation in air atmosphere at room temperature. The [Ag(NH₃)₂]⁺was reduced to silver atoms upon ultraviolet irradiation. Silver atoms subsequently deposited on the surface of silica spheres and agglomerated into silver nanoparticles. Silica spheres with silver nanoparticles of different size and density can be simply controlled by adjusting the UV-light irradiation time. The silver nanoparticles deposited on silica spheres were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy.     

Preparation of Au nanoparticles by Q switched laser ablation and their application in 4-nitrophenol reduction

Clean Technologies and Environmental Policy - This work reports the fabrication of Au nanoparticles (NPs) by laser ablation of a gold metal plate immersed in water in the absence of stabilizing...     

Formation of silver nanoparticles by through thin film ablation

Well dispersed Ag nanoparticles have been formed by a process denoted Through Thin Film Ablation. The nanoparticles were deposited on room temperature substrates, had a most probable size of 1 nm, and were not agglomerated. The nanoparticle deposit produced by this process showed no evidence of the larger particles commonly observed from conventional pulsed laser ablation that uses a bulk target. Synthesis of nanoparticles by Through Thin Film Ablation should be possible for any material that can be made as a thin film target and may enable the unique properties of isolated, non-agglomerated nanoparticles to be exploited more fully.     

Synthesis and characterization of fluorophore attached silver nanoparticles

Silver nanoparticles stabilized by soluble starch were synthesized and characterized. In vivo studies in rats showed no toxicity and revealed their distribution in various tissues and permeability across BBB. This starch stabilized silver nanoparticles have good biological characteristics to act as a potential promising vector for gene/drug delivery.     

Synthesis and characterization of L-histidine capped silver nanoparticles

L-histidine capped Ag nanoparticles have been synthesized by a hydrothermal method. Spherical Ag nanoparticles with average diameter ranging from 9 to 21 nm can be obtained by tuning the reaction pH and the reactant ratio. The topography, surface and internal structures of the histidine capped Ag nanoparticles have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering, X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), Raman spectroscopy and UV–vis absorption spectroscopy. Surface enhanced Raman scattering (SERS) results revealed that the Ag colloid in present study have a structure that the imidazole moiety of histidine is bound on the Ag surface and COO^? group is exposed outward. The as-synthesized Ag colloidal solution was very stable and can be stored at room temperature at least one month. In addition, it was found that the solution color of Ag colloid can change from yellow to reddish-brown by addition of the NiCl₂ solution, which may have potential application for Ni²⁺ detection.     

Zinc nanoparticles in solution by laser ablation technique

Colloidal zinc metallic nanoparticles are synthesized using pulsed laser ablation of metal plate in an aqueous solution of suitable surfactant to prevent aggregation. UV-visible absorption, TEM, small angle X-ray diffraction and wide-angle X-ray diffraction are used for the characterization of colloidal zinc metallic nanoparticles. Colloidal nanoparticles are found highly stable for a long time.     

纳米银粒子的制备及其表征

采用聚乙烯吡咯烷酮、无水乙醇和去离子水混合溶液,利用水合肼还原硝酸银制备纳米银粒子.利用透射电子显微镜,紫外-可见吸收光谱和X射线衍射对纳米银粒子进行表征.结果表明,该法制备的纳米银粒子杂质含量低,粒度分布集中,颗粒均匀一致,形貌呈球形.     

Preparation and characterization of pyrazoline nanoparticles

Nanoparticles of 1-phenyl-3-naphthyl-5-((dimethylamino)phenyl)-2-pyrazoline ranging from tens to hundreds of nanometers were prepared by the reprecipitation method. Their excitonic transitions responsible for absorption and emission, as compared with those of dilute solution, have been investigated as a function of nanoparticle size. We found that pyrazoline nanoparticles possess a special size dependence on their optical properties. As the nanoparticle size decreased, the molecular absorption peak of pyrazoline nanoparticles was observed to shift to the high-energy side due to size effect.     

纳米碲粉体的制备及表征

利用惰性气体保护蒸发-冷凝法制备了碲（Te）纳米粉体颗粒。通过热力学计算得到碲的蒸汽压随温度的变化关系。利用X射线衍射（XRD）、透射电子显微镜（TEM）、激光粒度仪观测了碲纳米颗粒的晶体结构、形貌,并研究了粉末粒径、分布及形貌与蒸发冷凝过程中气氛压力的关系。结果表明,随着气氛压力的增加,粉末粒径分布范围变窄,粉末粒度...     

Preparation and characterization of honokiol nanoparticles

In this paper, honokiol nanoparticles were prepared by emulsion solvent evaporation method. The prepared honokiol nanoparticles were characterized by particle size distribution, morphology, zeta potential and crystallography. Results showed that the obtained honokiol nanoparticles at size of 33 nm might be amorphous, and could be well dispersed in water. Due to the great dispersibility in water, the obtained honokiol nanoparticles might have great potential in medical field.