Controlling the Chemistry of Nanoclusters: From Atomic Precision to Controlled Assembly

Metal nanoclusters have gained prominence in nanomaterials sciences, owing to their atomic precision, structural regularity, and unique chemical composition. Additionally, the ligands stabilizing the clusters provide great opportunities for linking the clusters in higher order dimensions, eventually leading to the formation of a repertoire of nanoarchitectures. This makes the chemistry of atomic clusters worth exploring. In this mini review, we aim to focus on the chemistry of nanoclusters. Firstly, we summarize the important strategies developed so far for the synthesis of atomic clusters. For each synthetic strategy, we highlight the chemistry governing the formation of nanoclusters. Next, we discuss the key techniques in the purification and separation of nanoclusters, as the chemical purity of clusters is deemed important for their further chemical processing. Thereafter which we provide an account of the chemical reactions of nanoclusters. Then, we summarize the chemical routes to the spatial organization of atomic clusters, highlighting the importance of assembly formation from an application point of view. Finally, we raise some fundamentally important questions with regard to the chemistry of atomic clusters, which, if addressed, may broaden the scope of research pertaining to atomic clusters.

Synthesis and study of some properties of colloidal quantum dots of indium antimonide

Colloidal quantum dots of indium antimonide have been synthesized by a known technique. The shape and average diameters of quantum dots have been investigated by transmission electron microscopy using a transmission microscope. Controlling the size and shape of colloidal QDs provides information on the formation of the crystal structure of nanoparticles and their possible physical and optical properties. It has been found that InSb quantum dots are characterized by a polygonal shape. The results obtained for QDs correspond to the crystal lattice system of a semiconductor with a cubic crystal lattice structure. Elemental analysis of nanoparticles has been monitored by X-ray microanalysis. The experimental determination error was no more than one percent. The percentages of indium and antimony in QDs according to X-ray microanalysis data corresponded to the theoretical stoichiometry In: Sb = 1:1. Impurities of other elements constituted the level of trace amounts, which confirmed the chemical purity of the synthesized InSb QDs. The fluorescent properties of indium antimonide nanoparticles have been studied. It has been found that the luminescence intensity of InSb nanoparticles at room temperature is insignificant, which is in agreement with the literature data. The quantum yield does not exceed 1%, and the luminescence maximum lies in the range of 1040 nm.

Preparation of silicon and alumosilicic aerogels based on the decomposition of nepheline with an alcoholic solution of sulfuric acid

The results of studies on the production of silicon and aluminum-silicon aerogels from nepheline are presented. The morphology of the obtained samples was studied. Their chemical purity was proved by the method of X-ray elemental analysis. The structural and surface properties of the resulting aerogel are presented, such as: specific surface area (843.62 и 503.99 m2/g) and pore volume (0.396 и 0.237 cm3/g), average pore size (1.870 nm). Data on the skeletal density of the obtained samples are given

Cyclotron production and radiochemical purification of terbium-155 for SPECT imaging

Background Terbium-155 [T1/2 = 5.32 d, Eγ = 87 keV (32%) 105 keV (25%)] is an interesting radionuclide suitable for single photon emission computed tomography (SPECT) imaging with potential application in the diagnosis of oncological disease. It shows similar decay characteristics to the clinically established indium-111 and would be a useful substitute for the diagnosis and prospective dosimetry with biomolecules that are afterwards labeled with therapeutic radiolanthanides and pseudo-radiolanthanides, such as lutetium-177 and yttrium-90. Moreover, terbium-155 could form part of the perfect “matched pair” with the therapeutic radionuclide terbium-161, making the concept of true radiotheragnostics a reality. The aim of this study was the investigation of the production of terbium-155 via the 155Gd(p,n)155Tb and 156Gd(p,2n)155Tb nuclear reactions and its subsequent purification, in order to obtain a final product in quantity and quality sufficient for preclinical application. The 156Gd(p,2n)155Tb nuclear reaction was performed with 72 MeV protons (degraded to ~ 23 MeV), while the 155Gd(p,n)155Tb reaction was degraded further to ~ 10 MeV, as well as performed at an 18 MeV medical cyclotron, to demonstrate its feasibility of production. Result The 156Gd(p,2n)155Tb nuclear reaction demonstrated higher production yields of up to 1.7 GBq, however, lower radionuclidic purity when compared to the final product (~ 200 MBq) of the 155Gd(p,n)155Tb nuclear reaction. In particular, other radioisotopes of terbium were produced as side products. The radiochemical purification of terbium-155 from the target material was developed to provide up to 1.0 GBq product in a small volume (~ 1 mL 0.05 M HCl), suitable for radiolabeling purposes. The high chemical purity of terbium-155 was proven by radiolabeling experiments at molar activities up to 100 MBq/nmol. SPECT/CT experiments were performed in tumor-bearing mice using [155Tb]Tb-DOTATOC. Conclusion This study demonstrated two possible production routes for high activities of terbium-155 using a cyclotron, indicating that the radionuclide is more accessible than the exclusive mass-separated method previously demonstrated. The developed radiochemical purification of terbium-155 from the target material yielded [155Tb]TbCl3 in high chemical purity. As a result, initial cell uptake investigations, as well as SPECT/CT in vivo studies with [155Tb]Tb-DOTATOC, were successfully performed, indicating that the chemical separation produced a product with suitable quality for preclinical studies.

A Facile Route of Manufacturing of Silicon-Based Nanostructures with Tuned Plasmonic Properties

An environment-friendly method of pulsed laser ablation in liquids is successfully employed for structural modification of silicon nanoparticles leading to a considerable narrowing of their size distribution accompanied with a reduction of the mean size. Contamination-free conditions of synthesis ensure the chemical purity of formed nanostructures that may reduce toxicity issues. Such a laser-induced modification leads to the appearance of plasmonic properties in semiconductor-based nanomaterials. Their spectral position can easily be varied in the whole visible range. Combined in one nanoparticle properties of semiconductors and noble metals can strongly promote applications of composite laser-synthesized nanoparticles for biosensing (using their plasmonic-based surface-enhanced ability) and bioimaging (using their both optical and magnetic abilities) purposes.

GMP-Compliant Radiosynthesis of [18F]GP1, a Novel PET Tracer for the Detection of Thrombi

Thrombus formation and thromboembolic events play important roles in various cardiovascular pathologies. The key receptor involved in platelet aggregation is the fibrinogen receptor glycoprotein IIb/IIIa. [18F]GP1, a derivative of the GPIIb/IIIa antagonist elarofiban, is a specific 18F-labeled small-molecule radiotracer that binds with high affinity to GPIIb/IIIa receptors of activated platelets. An improved, robust and fully automated radiosynthesis of [18F]GP1 has been developed. [18F]GP1 has been synthesized with decay corrected radiochemical yields of 38 ± 6%, with a radiochemical concentration up to 1900 MBq/mL, molar activities of 952–9428 GBq/µmol and a radio-chemical purity >98%. After determination of the optimal reaction conditions, in particular for HPLC separation, adaption of the reaction conditions to PET center requirements, validation of the manufacturing process and the quality control methods, the synthesis of [18F]GP1 was successfully implemented to GMP standards and was available for clinical application. We describe the GMP-compliant synthesis of the novel radiotracer [18F]GP1. Moreover, we provide some proof-of-concept examples for clinical application in the cardiovascular field. PET/CT with the novel small-molecular radiotracer [18F]GP1 may serve as a novel highly sensitive tool for visualizing active platelet aggregation at the molecular level.

Morphology and Chemical Purity of Water Suspension of Graphene Oxide FLAKES Aged for 14 Months in Ambient Conditions. A Preliminary Study

Graphene and its derivatives have attracted scientists’ interest due to their exceptional properties, making them alluring candidates for multiple applications. However, still little is known about the properties of as-obtained graphene derivatives during long-term storage. The aim of this study was to check whether or not 14 months of storage time impacts graphene oxide flakes’ suspension purity. Complementary micro and nanoscale characterization techniques (SEM, AFM, EDS, FTIR, Raman spectroscopy, and elemental combustion analysis) were implemented for a detailed description of the topography and chemical properties of graphene oxide flakes. The final step was pH evaluation of as-obtained and aged samples. Our findings show that purified flakes sustained their purity over 14 months of storage.

A New Sterilization Strategy Using TiO2 Nanotubes for Production of Free Radicals that Eliminate Viruses and Application of a Treatment Strategy to Combat Infections Caused by Emerging SARS-CoV-2 during the COVID-19 Pandemic

Synthesized titanium oxide nanoparticles (TiO2-NPs) nanotubes were used for the disinfection of new emerging corona virus-19 (SARS-CoV-2) in this study. The newly synthesized TiO2-NPs (nanotubes) were characterized by chemical spectroscopic analysis Fourier-transform infrared spectroscopy and ultraviolet FT-IR and UV. The chemical purity and Zeta potential distribution of the TiO2-NPs (nanotubes) were evaluated to confirm their nano-range, and their surface morphology was determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy dispersive X-ray analysis (EDX). The antiviral activity of the TiO2-NPs (nanotubes) against SARS-CoV-2 was evaluated using 10% (Dimethyl sulfoxide) DMSO and dist.H2O using a cytotoxicity assay and inhibitory concentration assay (to determine the cytotoxic half concentration CC50 and half maximal inhibitory concentration IC50). The current results confirmed that TiO2-NPs exhibit strong anti-SARS-CoV-2 activity at very low cytotoxic concentrations in vitro with a non-significant selectivity index (CC50/IC50 ≤ 1). The obtained results indicate that TiO2-NPs and nanotubes have potent antiviral activity at a very low concentrations (IC50 = 568.6 ng/mL), with a weak cytotoxic effect on the cellular host (CC50 = 399.1 ng/mL). Thus, we highly recommend the use of TiO2-NPs (nanotubes) in vitro and in wall coatings as a potent disinfectant to combat SARS-CoV-2 with little irritation of the cellular hosts. Furthermore, we also recommend more and excessive prospective studies on the complexation of natural active or natural compounds with TiO2-NPs (nanotubes) to minimize their cytotoxicity, enhance their antiviral activity, and increase their inhibition of SARS-CoV-2.

Matrices, based on nanostructured porous anodic alumina, for functional applications

Two-step electrochemical anodization was used for obtaining matrices based on porous anodic alumina (MPAA). Three series of experimental samples were made: 1 – PAAM with thickness 1.3–2.5 μm and 70 nm diameter, 2 – 70.0 μm thickness and 50–75 nm diameter and 3 – 13.5–60.0 μm thickness and 100–200 nm diameter. The pore filling of MPAA was realized using electrochemical deposition. As a result Ni nanopillars, Ni and multilayered Cu/CoNi nanowires were formed. The scanning electron microscopy, vibrating magnetometry, voltammetry techniques and four-probe method were used for experimental samples investigations. The magnetic characteristics of Ni nanowires showed that nanowires in MPAA have ferromagnetic properties, since the coercitivity riches up to 750 kOe and squareness ratio up to 0.65. The study of the electrochemical behavior of the Ti/Al2O3/Ni nanocomposite material in the potential range from –450 to +450 mV in 0.9 % NaCl aqueous solution demonstrated its high corrosion resistance properties. The correlation of the GMR of multilayered Cu/CoNi nanowires to the topological parameters of MPAA, the number of layers, the MPAA and partial layers thickness, and chemical purity has been determined. Thus, it has been demonstrated the prospects of use of matrices based on porous anodic alumina as a base material for the template synthesis of functional ferromagnetic nanomaterials for various practical applications.