Additive effects of guanidinium [C(NH₂)₃, GA] iodide, formamidinium [CH(NH₂)₂, FA] iodide, and guanidinium chloride to CH₃NH₃PbI₃-based photovoltaic devices were investigated. Short-circuit current densities, open-circuit voltages, series resistances and shunt resistances were improved by the GA addition. The short-circuit current densities were increased by FA addition with GA, and the external quantum efficiencies increased, which results from the suppression of pin-holes in perovskite layers by GA addition. X-ray diffraction showed that the lattice constants of the perovskite crystals increased by the GA and FA addition, and that the GA substituted partially at the CH₃NH₃-site.

Influence of alkali metals (Na, K) and transition metals (Co, Cr, Cu, and Y) incorporated into perovskite crystal on the electronic structures, spectroscopic and magnetic properties, and thermodynamic properties was investigated by first-principles calculation using density functional theory. Incorporation of 12.5% Na or K into the perovskite crystal generated 3s, 3p, 4s, and 4p orbitals of Na or K above the conduction band, which promoted the charge transfer from alkali metal to the conduction band, accelerating the electron diffusion related to the photovoltaic properties. For the Cr, Cu and Y-incorporated FAPbI₃ perovskite crystals, the electron density distribution of d-p hybrid orbital on the transition metal and iodine halogen ligand were delocalized at the frontier orbital.

A microwave method was used for the synthesis of TiO₂-ZnO oxide systems. A detailed investigation was made of the effect of the molar ratio of components (TiO₂:ZnO=9:1, 7:3, 5:5, 3:7, 1:9) on the crystalline structure and morphology. Based on the TEM pictures, confirmed the presence of octahedral and rod-shaped titania particles and sheet zinc oxide particles. Moreover, the synthesized materials were analyzed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), and two crystalline forms - anatase and wurtzite were detected. Based on the adsorption-desorption N₂ isotherms confirmed mesoporous characters of the analyzed binary materials, also the parameters of the porous structure have been defined. The key element of the work was to determine the photocatalytic activity of the obtained TiO₂-ZnO oxide systems in the degradation of phenol. Photo-oxidation tests proved that the binary oxide materials (especially the (9)TiO₂-(1)ZnO and (7)TiO₂-(3)ZnO samples) demonstrate high photocatalytic activity in the decomposition of phenol (95% after 80 min irradiation) compared with the reference titania sample. Furthermore, it was also pointed out that the dye-sensitized solar cells can be a second application for the synthesized TiO₂-ZnO materials. The best photovoltaic parameters have been found in the case of the (9)TiO₂-(1)ZnO material, which was characterized by an efficiency of 8.84%. The improvement effect is caused by introducing a material (ZnO) with a higher conductivity band into the TiO₂-ZnO oxide system, additionally improving the transport of electrons inside the semiconductor layer.

Single-molecule magnets (SMMs) are the new class of nanoscale materials with unique magnetic properties of purely molecular origin, which are particularly interesting in terms of applications in nanoelectronics. The realization of highly-performance nanoelectronic devices based on the manipulation of SMMs requires surface deposition of such entities. The organization of individual bistable magnetic molecules on the surface, however, demands the precise chemical method and searching of proper supporting material, since any changes at structure may influence on the magnetic properties. Moreover, for practical application it is important to follow the changes of SMMs magnetic performance with the time.

In such study we present a possibility for deposition of Mn₁₂-based SMMs on the surface of silica nanostructures with preservation of its structure and magnetic properties. The procedure was based on anchoring the individual SMMs onto the silica support using propyl carbonic acid groups. The performed spectroscopy analysis confirm correct anchoring of molecules on the surface while magnetic measurements show retaining of magnetic hysteresis and slow relaxation process after surface deposition. In order to analyze how the characteristics of such material change over long time period the aging effect was investigated. The aging studies revealed significant decrease in basic magnetic parameters (coercivity and remanence) and change in magnetic relaxation behavior. The Raman spectroscopy measurements revealed gradual degradation of the compound over time, which explain the observed magnetic changes. Also, the aged samples were compared with the as-synthesized material after thermal decomposition to check, if the structural modifications caused by the temperature, affect the similar way as aging process.

In the presented work, we would like to present a new concept of a 2D solid solvent. This is a material, capable of selective ion or molecules capturing thanks to its developed surface, which is treated as a deposited on a substrate (usually spherical nano-silica or mesoporous silica) 2D bi- or multi-component layer. The latter one consists out of two main components – active anchoring units and passive spacers that are surface analogues of solute and solvent in an ordinary solution. The role of spacer units in this system is to separate active anchoring units to avoid their self-interactions and to create the required environment or ensure hydrophobicity/hydrophilicity of the entire system. The role of anchoring molecules, in turn, is to capture ions or molecules via the corresponding reactions, which can be treated as analogues of the occupation of free cites in the interstitial solid solutions. Whereas silica substrate, anchoring units and spacers are connected and act cooperatively for one final goal we consider to describe them as one part – solid solvent.

This class of material has great applicative potential in such areas as nanophotonics, electronics, catalysis and medicine, to name a few. In our work, we will clarify a definition of solid solvents as well as show some examples of them and their properties.

The endohedral chemical functionalization of single-walled carbon nanotubes (SWCNTs) allows tuning their electronic properties toward applications. It was demonstrated that the SWCNTs can be filled with elementary substances, chemical compounds and molecules [1].

In this work, we performed the filling of SWCNTs with metal halogenide (cobalt iodide, CoI₂) and metal carbide (nickel carbide, Ni₃C). The filling of SWCNTs with CoI₂ was conducted by the melt method. The filling of SWCNTs with Ni₃C was performed by the thermal treatment of nickelocene-filled nanotubes. The filled SWCNTs were investigated by high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The HRTEM data prove the encapsulation of compounds inside the SWCNTs. By combining the Raman spectroscopy and XPS data, it was shown that the encapsulated CoI₂ causes p-doping of nanotubes accompanied by the downshift of the Fermi level of nanotubes. The embedded Ni₃C leads to n-doping of SWCNTs with upshifting of the Fermi level of nanotubes. The obtained results allow applying the filled SWCNTs in the range of fields such as nanoelectronics, energy storage, sensors, catalysis and biomedicine.

[1] M. V. Kharlamova. Advances in tailoring the electronic properties of single-walled carbon nanotubes. Progress in Materials Science 2016, 77, 125-211.

Nanoparticles of gold and silver are commonly used in making sensors, probes, conducting inks, optical spectroscopies, diagnostic catalysts etc. Nanoparticles of these noble metals are also used as an antibacterial agent. Wound healing property and rate of wound healing using metals nanoparticles are under investigation and it has become frontier research area of current times. To explore the tissue growth property of these nanoparticles, the scratch assay has been performed on various metal nanoparticles under similar conditions of concentration and time duration. Biological synthesis route is used to synthesized metal nanoparticles. Nanoparticles of silver and gold were prepared using aloe vera (A) and turmeric (T) extract and for comparison purpose, these were also synthesized using chemicals in the same size range.

DMEM medium along with embryonic serum was used for the culture in standard culture Petri-dishes. The growth of the cells has been measured in terms of the area retrieved from scratch. Area of the empty portion is measured at the time the scratch is made (Day 0). Different nanoparticles were inoculated in these Petri-dishes and the area recovered via cell growth is measured after one day (Day 1) and two days (Day 2) later. It is observed that silver nanoparticles prepared using aloe vera and turmeric extracts is giving continuous cell growth under the entire duration of the study. However, for other agents used there is an initial growth and then a deterioration was observed. We also carried out the scratch test by varying the concentration of the agents used for inoculations. The results obtained using various nanoparticles were compared with the distilled water and known anti-hemorrhagic and antiseptic agents.

Nanomedicines inability to penetrate throughout the entire tumor volume due to heterogeneous distribution within the tumor mass remains a crucial limiting factor for a vast range of theranostic applications, including image-guided radiation therapy. Despite innumerable studies conducted on the topic have shown efficacy and biocompatibility of colloidal gold nanoparticles (GNPs), the biological effects of GNPs in the tumor microenvironment, including the particle-protein interaction and the consequent impact on cellular pathways and contrast enhancement remain unclear. In this regard, further investigations on how GNP surface passivation effects X-ray attenuation as well as in vivo biodistribution will clarify several aspects still under discussion from the scientific community, which so far have limited the clinical translation of their applications cancer-related.

We aim to evaluate the influence of protein surface adsorption on the GNP biodistribution in Lewis Lung Carcinoma (LLC) tumor-bearing mice using high resolution Computed Tomography (CT) preclinical imaging. We hypothesize that by controlling the adsorption of proteins on the GNP surface, we can influence the intratumoral distribution and retention of the particles.

GNPs approximately 34 nm in diameter are synthesized with a surface plasmon peak at ~530 nm, surface passivated with Bovine Serum Albumin (BSA) to reduce opsonization and improve colloidal stability, and characterized with standard methods. Modulation of BSA adsorption on the GNPs is observed by tuning the pH of the immobilization medium from acidic to alkaline, which we quantify using Langmuir isotherms. CT phantom imaging is used to determine X-ray attenuation as a function of GNP concentration and surface functionalization. The in vitro study for evaluating the uptake of GNPs by Lewis Lung Carcinoma cells highlighted a difference in the internalization depending on the surface functionalization. In both cases, macropinocytosis is the trafficking mechanism, but while endosomes with citrate-GNPs can be found in different stages of maturation, cells treated with BSA-GNPs presented larger vesicles up to 1μm in diameter. The in vivo study is performed by injecting intratumorally, concentrated GNPs into Lewis Lung Carcinoma (LLC) solid tumors grown on the right flank of 6-week old female C57BL/6 mice. Ten days post-injection, follow-up assessments with CT imaging show the distribution and retention of the particles in the tumor. CT attenuation quantification based on bioimaging analysis for each time point is conducted.

In vivo results show significant heterogeneity in the intratumoral biodistribution of GNPs dependent on surface passivation. BSA-GNPs perfuse predominately along the tumor periphery with few depositions throughout the entire tumor volume. This response can be explained by the abnormal and heterogeneous vascular structure of the LLC tumor, suggesting perfusion rather than permeability as the limiting factor for tumor accumulation of the GNPs. Despite the perivascular cluster accumulation, the BSA-GNP distribution diverges from that obtained after unpassivated, citrate-GNP intratumoral injections.

In conclusion, our investigations have shown that surface passivation of GNPs is able to influence the mechanism of cellular uptake in vitro and their in vivo intratumoral diffusion highlighting the spatial heterogeneity of the solid tumor.

Organic-inorganic hybrid perovskite solar cells have resulted in tremendous interest in developing future generation solar cells due to high efficiency exceeding 25%. For inverted type perovskite solar cells, the hole transporting layer plays a crucial role in improving the efficiency and stability of the perovskite solar cells by modifying band alignment, electric conductivity, and interfacial recombination losses. Here, vanadium doped NiO is selected as a hole transporting layer to study the impact of V dopant on the optoelectronic properties of NiO and the photovoltaic performance. The prepared materials are characterized using XRD, SEM, TEM, and XPS. TEM micrograph confirms that p-type materials have small spherical dot structure. The V-doped NiO used as a hole-extraction layer can be prepared by the simple solvothermal decomposition method. The presence of V in the NiO layer has an influence on the conductivity of the NiO layer. In addition, synthesized p-type material can be used to fabricate relatively low processing temperature has the advantage of a wide choice of transparent conductive oxide substrate. As a result, inverted type planar perovskite solar cell incorporating of V:NiO hole-transport layer is improved power conversion efficiency. The photovoltaic property of the prepared solar cell is measured under AM 1.5 G simulated light and the results are listed in Table 1. The photo-current density is 21.09 mA/cm², open-circuit voltage is 1.04 V, and the fill factor is 0.63. As a result, the overall power conversion efficiency reaches 13.82%.

Human neuroblastoma (NB) is a pediatric tumor, which, after an initial response to therapy, usually develops resistance. Etoposide (ETO) which is a drug commonly used to clinically treat NB, exerts anticancer effects by increasing reactive oxygen species (ROS) generation [1,2]. Similarly, gallic acid (GA), although not specifically in NB treatment, exerts pro-oxidant anti-cancer effects associated to low toxicity for healthy cells. Unfortunately, low stability, poor solubility and an unfavorable pharmacokinetic negatively influence ETO and GA efficacy [1, 2]. To address GA and ETO issues, biodegradable dendrimer nanoparticles (DNPs) were prepared for entrapping ETO [2], as well as for encapsulating and covalently binding GA, obtaining the drugs-loaded dendrimers ETOD, GALD and GAD [1, 2]. The cytotoxic activity of DNPs, GA, ETOD, GALD and GAD was tested on ETO-sensitive and ETO-resistant NB cells. Unexpectedly, DNPs were able to exert per se a ROS-mediated cytotoxic activity comparable to ETO, on both cell populations. ETOD, combining DNPs and ETO, showed a synergistic action of the two molecules, a slow release of the drug and a significantly improved protracted bioactivity [2]. Free GA proved a dose-dependent ROS-mediated cytotoxicity on both cell populations, but intriguingly, when administered in dendrimer formulations, at a dose not cytotoxic for NB cells, nullified any pro-oxidant activity of DNPs [1]. Collectively, DNPs could represent a platform to develop novel devices against NB, while ETOD could be a biodegradable device for the efficient delivery of ETO into NB cells. GALD and GAD, due to the presence of GA, were inactive on NB cells, but GA resized in nanoparticles and at very low dose has shown considerable ability in counteracting ROS production induced by DNPs, thereby exerting a possible protective action for healthy cells.

1. Alfei, S.; Marengo, B.; Zuccari, G.; Turrini, F.; Domenicotti, C. Dendrimer Nanodevices and Gallic Acid as Novel Strategies to Fight Chemoresistance in Neuroblastoma Cells. Nanomaterials 2020, 10, 1243.
2. Alfei, S.; Marengo, B.; Domenicotti, C. Polyester-Based Dendrimer Nanoparticles Combined with Etoposide Have an Improved Cytotoxic and Pro-Oxidant Effect on Human Neuroblastoma Cells. Antioxidants 2020, 9, 50.