Comparative Analysis of Raman Signal Amplifying Effectiveness of Silver Nanostructures with Different Morphology

To increase the attractiveness of the practical application of molecular sensing methods, the experimental search for the optimal shape of silver nanostructures allowing to increase the Raman cross section by several orders of magnitude is of great interest. This paper presents a detailed study of spatially separated plasmon-active silver nanostructures grown in SiO2/Si template pores with crystallite, dendrite, and “sunflower-like” nanostructures shapes. Nile blue and 2-mercaptobenzothiazole were chosen as the model analytes for comparative evaluation of the Raman signal amplification efficiency using these structures. It was discussed the features of the structures for the enhancement of Raman intensity. Finally, we showed that silver crystals, dendrites, and “sunflower-like” nanostructures in SiO2/Si template could be used as the relevant materials for Raman signal amplification, but with different efficiency

Morphology and Microstructure Evolution of Gold Nanostructures in the Limited Volume Porous Matrices

The modern development of nanotechnology requires the discovery of simple approaches that ensure the controlled formation of functional nanostructures with a predetermined morphology. One of the simplest approaches is the self-assembly of nanostructures. The widespread implementation of self-assembly is limited by the complexity of controlled processes in a large volume where, due to the temperature, ion concentration, and other thermodynamics factors, local changes in diffusion-limited processes may occur, leading to unexpected nanostructure growth. The easiest ways to control the diffusion-limited processes are spatial limitation and localized growth of nanostructures in a porous matrix. In this paper, we propose to apply the method of controlled self-assembly of gold nanostructures in a limited pore volume of a silicon oxide matrix with submicron pore sizes. A detailed study of achieved gold nanostructures' morphology, microstructure, and surface composition at different formation stages is carried out to understand the peculiarities of realized nanostructures. Based on the obtained results, a mechanism for the growth of gold nanostructures in a limited volume, which can be used for the controlled formation of nanostructures with a predetermined geometry and composition, has been proposed. The results observed in the present study can be useful for the design of plasmonic-active surfaces for surface-enhanced Raman spectroscopy-based detection of ultra-low concentration of different chemical or biological analytes, where the size of the localized gold nanostructures is comparable with the spot area of the focused laser beam

Ellipsometry as an express method for determining the pore parameters of ion-track SiO2 templates on a silicon substrate

Due to the effective development of ion-track technology, it became possible to produce porous templates with large areas, which are of interest for mass production of nanostructures. Given that the template parameters often define properties of the resulting nanostructures and nanosystems, a reliable method for non-destructive testing is needed for a rapid control of template parameters. Such method could be ellipsometry, allowing for a single measurement to collect statistical information from a large area and to save time for certification. In order to adapt the ellipsometry method for controlling the parameters of ion-track patterns, the first studies of SiO2/Si templates with low porosity were carried out. Using the standard model of the interaction of a polarized light beam with a layered structure of silicon oxide on silicon, the basic parameters of the pores were determined by means of mathematical transformations and subsequently compared with the results of scanning electron microscopy

Ellipsometry as an express method for determining the pore parameters of ion-track SiO

Due to the effective development of ion-track technology, it became possible to produce porous templates with large areas, which are of interest for mass production of nanostructures. Given that the template parameters often define properties of the resulting nanostructures and nanosystems, a reliable method for non-destructive testing is needed for a rapid control of template parameters. Such method could be ellipsometry, allowing for a single measurement to collect statistical information from a large area and to save time for certification. In order to adapt the ellipsometry method for controlling the parameters of ion-track patterns, the first studies of SiO2/Si templates with low porosity were carried out. Using the standard model of the interaction of a polarized light beam with a layered structure of silicon oxide on silicon, the basic parameters of the pores were determined by means of mathematical transformations and subsequently compared with the results of scanning electron microscopy

Influence of media with different acidity on structure of FeNi nanotubes

A detailed analysis of the structure features of FeNi nanotubes exposed at environment with different acidity is carried out. It is demonstrated that the exposure of the nanostructures in the environment with high acidity causes the structure deformation, leading to sharply increasing of the presents of oxide phases and partial amorphization of nanotubes walls that determined the rate of FeNi nanotubes destruction. It was established that the evolution of the crystal structure parameters concerned with appearance of oxide phases and with formation of disorder regions as a result of oxidation processes

One-Step Synthesis of Magnetic Nanocomposite with Embedded Biologically Active Substance

Magnetic nanocomposites based on hydroxyapatite were prepared by a one-step process using the hydrothermal coprecipitation method to sinter iron oxides (Fe3O4 and γ-Fe2O3). The possibility of expanding the proposed technique for the synthesis of magnetic composite with embedded biologically active substance (BAS) of the 2-arylaminopyrimidine group was shown. The composition, morphology, structural features, and magnetic characteristics of the nanocomposites synthesized with and without BAS were studied. The introduction of BAS into the composite synthesis resulted in minor changes in the structural and physical properties. The specificity of the chemical bonds between BAS and the hydroxyapatite-magnetite core was revealed. The kinetics of the BAS release in a solution simulating the stomach environment was studied. The cytotoxicity of (HAP)FexOy and (HAP)FexOy + BAS composites was studied in vitro using the primary culture of human liver carcinoma cells HepG2. The synthesized magnetic composites with BAS have a high potential for use in the biomedical field, for example, as carriers for magnetically controlled drug delivery and materials for bone tissue engineering

Influence of media with different acidity on structure of FeNi nanotubes

A detailed analysis of the structure features of FeNi nanotubes exposed at environment with different acidity is carried out. It is demonstrated that the exposure of the nanostructures in the environment with high acidity causes the structure deformation, leading to sharply increasing of the presents of oxide phases and partial amorphization of nanotubes walls that determined the rate of FeNi nanotubes destruction. It was established that the evolution of the crystal structure parameters concerned with appearance of oxide phases and with formation of disorder regions as a result of oxidation processes