Chapter 3 - Characterization of nanoparticles

Versatile aerosol concentration enrichment system (VACES) for simultaneous in vivo and in vitro evaluation of toxic effects of ultrafine, fine and coarse ambient particles Part II: Field evaluation

Silver nanoparticles with a narrow size distribution were synthesized over the surface of two differentcommercial TiO2 particles using a simple aqueous reduction method. The reducing agent used wasNaBH4; differentmolar ratios TiO2:Ag were also used. The nanocomposites thus prepared were characterized usingtransmission electron microscopy (TEM), scanning transmission electron microscopy(STEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-rayphotoelectron spectroscopy (XPS), x-ray diffraction (XRD), dynamic light scattering(DLS) and UV–visible (UV–vis) absorption spectroscopy; the antibacterial activity wasassessed using the standard microdilution method, determining the minimuminhibitory concentration (MIC) according to the National Committee for ClinicalLaboratory Standards. From the microscopy studies (TEM and STEM) we observedthat the silver nanoparticles are homogeneously distributed over the surface ofTiO2 particlesand that the TiO2:Ag molar ratio plays an important role. We used three differentTiO2Ag molar ratios and the size of the silver nanoparticles is 10, 20 and 80 nm,respectively. It was found that the antibacterial activity of the nanocompositesincreases considerably comparing with separated silver nanoparticles andTiO2 particles.

Atmospheric aerosol is an omnipresent component of the Earth atmosphere. Aerosol particle of diameters < 100 nm or > 1 μm defines ultrafine or coarse aerosol particles, respectively. Aerosol particle concentrations within the planetary boundary layer - PBL are measured at the ground level while their vertical profiles in the PBL are usually estimated by modelling. The aim of this study was to construct vertical concentration profiles of ultrafine and coarse aerosol particles from airborne and ground measurements conducted in an urban airshed. Airborne measurements were done by an unmanned airship, remotely controlled with GPS 10 Hz position tracking, and electrically powered with propulsion vectoring, which allows average cruising speed of 6 m.s-1. The airship carried three aerosol monitors and a temperature sensor. The monitors acquired 1 Hz data on mass concentration of coarse and number concentration of ultrafine particles. Four flight sequences were conducted on the 2nd of March 2014 above Plesna village, up-wind suburb of Ostrava in the Moravian-Silesian region of the Czech Republic. The region is a European air pollution hot-spot. Repeated flights were carried out in several height levels up to 570 m above ground level - a.g.l. Early morning flight revealed a temperature inversion in the PBL up to 70 m a.g.l. This lead to coarse particle concentrations of 50 μgm-3 below the inversion layer and 10 μgm-3 above it. Concurrently, air masses at 90-120 m a.g.l. were enriched with ultrafine particles up to 2.5x104 cm-3, which may indicate a fanning plume from a distant emission source with high emission height. During the course of the day, concentrations of ultrafine and coarse particle gradually decreased. Nevertheless, a sudden increase of ultrafine particle concentrations up to 3.7x104 cm-3 was registered at 400 m a.g.l. at noon and also after a lag of 20 min at the ground. This may indicate formation of new aerosol particles at higher altitudes, which are then transported downward by evolved convective mixing. Detailed information acquired by the airship measurements allow us to better understand processes resulting in the increase of aerosol particle concentrations at ground level in urban air.

Zinc Oxide nanoparticles (ZnO) being biocompatible and chemically stable have great potential for bio-medical applications that includes anti-bacterial and mold prevention, air ventilation and purification, water purification, self cleaning and photosynthesis, and disease detection. Also ZnO is a wide band gap semiconductor and exhibits piezoelectric and pyroelectric properties, which makes it a perfect candidate for building electrochemically coupled sensors and transducers. With all these unique properties, ZnO has the potential to be very important nanomaterial in material research area. Therefore, research, development, and production of ZnO nanoparticles would make notable contributions to the field of nanotechnology. In this paper we report a novel approach for the fabrication of ZnO nanoparticles suspension in deionized water at room temperature using pulsed laser deposition (PLD) technique. Particle size was controlled by the number of shots of the laser beam used. Characterization of the nanoparticles has been done using UV-Visible spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). UV-Visible study confirmed the existence of ZnO nanoparticles showing a peak at around 300 nm which is consistent with the absorption spectra of standard ZnO nanoparticles. Presence of ZnO was reconfirmed by the excitation and emission spectra obtained from fluorescence spectroscopy. The excitation and emission peaks were found at 305 nm and 410 nm respectively, strongly suggesting the characteristic peaks for ZnO nanoparticles. Transmission electron microscope (TEM) photographs established that we have successfully prepared ZnO nanoparticles suspension with particle size ranging from 6 nm to 90 nm.

Decision letter: Dynamic Na+/H+ exchanger 1 (NHE1) – calmodulin complexes of varying stoichiometry and structure regulate Ca2+-dependent NHE1 activation

Black phosphorus (BP) is a newly discovered two-dimensional material that has promising applications from bioelectronics to biomedicine. However, facile oxidation of BP leads to changes in surface ...

The present investigation describes the synthesis and characterization of novel biodegradable nanoparticles based on chitosan. Poly(ethylene glycol) dicarboxylic acid was used for intramolecular cross-linking of the chitosan linear chains. The condensation reaction of carboxylic groups and pendant amino groups of chitosan was performed by using water-soluble carbodiimide. The prepared nanosystems were stable in aqueous media. The structure of the products was determined by nuclear magnetic resonance (NMR) spectroscopy, and the particle size was identified by dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. It was found that biodegradable cross-linked chitosan nanoparticles experienced considerable swelling because of the length and flexibility of the cross-linking agent. The aqueous solutions or dispersions of nanoparticles were stable and clear or mildly opalescent systems depending on the ratio of cross-linking and molecular weight of chitosan, findings consistent with values of transmittance above 75%. Particle size measured by TEM varied in the range of 4-24 nm. In the swollen state, the average size of the individual particles measured by DLS was in the range of 50-120 nm depending on the molecular weight of chitosan and the ratio of cross-linking.

This research presents a methodology for obtaining ZnS nanoparticles (NZnS). Doped with transition metal ions (MnCl2) and use of rare earth EuCl3 to improve their photoluminescence properties. Semiconductor nanoparticles were synthesized using the nanoprecipitation technique. The characterization of the ZnS nanoparticles was carried out using Dynamic Light Scattering (DLS), Powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HRTEM), and Luminescence Spectroscopy (PL) technique. A cubic zinc crystalline structure could be observed considering the position and intensity of the characteristic peaks in the XRD pattern. Also, taking the width at half height of the main peak and using the Debye-Scherrer equation, it is possible to obtain the average size of the nanoparticles, which for the samples analyzed was between 2-4 nm. SEM micrograph revealed a morphology with aggregated nanoparticles. High-Resolution Transmission Electron Microscopy showed the crystalline structure of the doped nanomaterial. PL characterization showed an increase in the luminescent intensity of doped NZnS compared to NZnS doped with the lowest concentration of the coating agent. These results confirm the effectiveness of the methodology for possible application in bioimaging diagnosis of PL in nanomedicine.

Dynamic light scattering (DLS) is an essential technique for nanoparticle size analysis and has been employed extensively for decades, but despite its long history and popularity, the choice of weighting and mean of the size distribution often appears to be picked ad hoc to bring the results into agreement with other methods and expectations by any means necessary. Here, we critically discuss the application of DLS for nanoparticle characterization and provide much-needed clarification for ambiguities in the mean-value practice of commercial DLS software and documentary standards. We address the misleading way DLS size distributions are often presented, that is, as a logarithmically scaled histogram of measured relative quantities. Central values obtained incautiously from this representation often lead to significant interpretation errors. Through the measurement of monomodal nanoparticle samples having an extensive range of sizes (5 to 250 nm) and polydispersity, we similarly demonstrate that the default outputs of a frequently used DLS inversion method are ill chosen, as they are regularizer-dependent and significantly deviate from the cumulant z-average size. The resulting discrepancies are typically larger than 15% depending on the polydispersity index of the samples. We explicitly identify and validate the harmonic mean as the central value of the intensity-weighted DLS size distribution that expresses the inversion results consistently with the cumulant results. We also investigate the extent to which the DLS polydispersity descriptors are representative of the distributional quality and find them to be unreliable and misleading, both for monodisperse reference materials and broad-distribution biomedical nanoparticles. These results overall are intended to bring essential improvements and to stimulate reexamination of the metrological capabilities and role of DLS in nanoparticle characterization.

Selenium nanoparticles (SeNPs) are of significant interest due to their potential applications in biomedicine, driven by their unique properties and antioxidant activities. However, their practical use is often hindered by issues such as instability and aggregation. In this study, a polysaccharide, P2, extracted from Ononis natrix was used to stabilize SeNPs to address these limitations. P2-SeNPs were prepared through a green synthesis method involving sodium selenite, P2 and ascorbic acid, and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). P2-SeNPs exhibited smaller particle size and enhanced stability compared to unmodified SeNPs. UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrated the presence of Se–O bonds, suggesting effective stabilization by covalent bonding between SeNPs and P2. Stability tests revealed that P2-SeNPs maintained good dispersion under various conditions, with optimal stability observed at refrigerated temperatures and neutral pH. Moreover, P2-SeNPs exhibited better antioxidant activities than unmodified SeNPs, as evidenced by higher DPPH radical scavenging, ABTS radical scavenging, and metal chelation ratios. This difference is attributed to both the reduced aggregation and smaller size of P2-SeNPs. Therefore, it is concluded that P2-SeNPs exhibit significant potential as an effective antioxidant agent for biomedical applications.

In this Article, we report on the encapsulation of decyl-modified silicon nanoparticles (decyl-SiNPs) into ∼80 nm lipid nanocapsules (LNCs). The decyl-SiNPs were produced by thermal hydrosilylation of hydride-terminated SiNPs (H-SiNPs) liberated from porous silicon. Various techniques, including Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), UV-vis absorption, dynamic light scattering (DLS), and photoluminescence (PL), were used to characterize their size, shape, colloidal, and optical properties. The results indicate that these nanocapsules feature controllable size, good dispersity, high loading rate of SiNPs, colloidal stability in various media, and bright PL. The PL of decyl-SiNPs loaded LNCs was stable upon heating to 80 °C, but was sensitive to basic solutions due to proton-gated emission of the SiNPs arranged at the LNCs interface between the oil phase and the hydrophilic polyethylene glycol moieties of the surfactant. These luminescent nanocapsules are therefore promising candidates as cellular probes for fluorescence imaging. In addition, it was found that TEM imaging of small-sized decyl-SiNPs could be greatly improved by preliminary negative staining of TEM grids with phosphotungstic acid.

Moringa oleifera (M. oleifera) is globally recognized for its medicinal properties and offers high-quality, protein-rich seeds. This study aimed to explore the potential of M. oleifera seeds as a significant source of protein-based nanoparticles (PBNPs) using the ultrasonication technique after desolvation and to evaluate their cytotoxicity in the human leukemia cell line (THP-1) for the first time. The properties of the PBNPs were confirmed by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The extracted protein from moringa seed cake flour had a significant protein content of 54.20%, and the resulting PBNPs had an average size of 134.3 ± 0.47 nm with a robust zeta potential of -43.15 mV. Notably, our study revealed that PBNPs exhibited cytotoxic potential at high concentrations, especially against the THP-1 human leukemia cell line, which is widely used to study immunomodulatory properties. The inhibitory effect of PBNPs was quantitatively evidenced by a cytotoxicity assay, which showed that a concentration of 206.5 μg mL-1 (log conc. 2.315) was required to inhibit 50% of biological activity. In conclusion, our findings highlight the potential of M. oleifera seeds as a valuable resource in the innovative field of eco-friendly PBNPs by combining traditional medicinal applications with contemporary advancements in protein nanotechnology. However, further studies are required to ensure their biocompatibility.

The use of superparamagnetic iron oxide nanoparticles (SPIONs) has gained increasing attention in the scientific community with experimental success recorded in medical science through magnetic hyperthermia in cancer treatment and targeted drug delivery. Determining how the nanoparticles and their capping agents react with their surroundings is imperative to optimizing treatments as well as researching new applications for inductively heated nanoparticles. Suspensions of iron oxide nanoparticles capped with TX-100 were prepared in both deionized (DI) water and saline solutions to create a comparison study. The samples were heated via induction, followed by TEM characterization and diffraction pattern analysis for the particles removed after exposure to the high-frequency oscillating magnetic fields. Additional characterization was performed with dynamic light scattering (DLS), magnetic force microscopy (MFM), and X-ray photoelectron spectroscopy (XPS), for determining subsequent changes in their colloidal properties, magnetic interaction, and composition. The introduction of a saline environment promoted clustering, of which its appearance was unique from the DI suspension. This clustering accompanied an increased specific absorption rate for the suspension; moreover, smaller nanoparticles were also observed around the exterior of the clusters. The change in the agglomeration of the nanoparticles within the saline suspensions, and knowledge of previous research into the behavior of TX-100 in the presence of electrolytes, suggests that the addition of sodium chloride salt brought about a chemical change within the samples. MFM measurements show that the particle clusters within the saline suspensions possess higher magnetic attractive forces, and when coupled with the calorimetric measurements gathered, it can be concluded that this positively affected the nanoparticles’ heat output. Such implications and conclusions found will prove useful in optimizing nanoparticle heating for applications such as magnetic hyperthermia.

The method of Fe3O4 magnetic nanoparticle synthesis by co-precipitation, modification by 3-aminopropylsilane and conjugation with pH-(low)-insertion peptide (pHLIP) is reported. The characterization of nanoparticles by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, elemental and thermogravimetric analyses as well as dynamic light scattering and z-potential measurements is provided. The effect of nanoparticles on the viability of mouse and human peripheral blood mononuclear cells is tested by flow cytometry. The experimental details of nanoparticle administration to tumor-bearing mice, magnetic resonance imaging scanning as well as subsequent tumor sample collection and their processing for transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, histological and immunohistochemical analyses are described. Biodistribution of the nanoparticles in mice and blood serum analysis data for experimental animals are given. The data are useful for an experiment workflow design and for the development of theranostic systems based on magnetic nanoparticles.

Characterization of the interaction between peptides derived from the gp120/V3 domain of HIV-1 and the amino terminal of the chemokine receptor CCR5 by NMR spectroscopy and light scattering