Monolayers of transition metal dichalcogenides (TMD) are direct bandgap semiconductors in which optical and spin properties are dominated by the formation of bound electron-hole pairs, excitons. Alloys of TDMS have emerged as materials with tunable electronic structures, effective masses of carriers, and valley polarization with various alloy compositions. In this work we investigate the low-temperature photoluminescence spectra of WSSe monolayer embedded in hexagonal boron nitride (hBN) layers using external magnetic fields. On this basis we extract g-factors which help us to distinguish excitonic complexes. Additionally, we study PL spectra in the function of laser power and temperature. Based on these experiments we identify emissions due to bright (exciton and trion) transitions and dark (negative trion) transition. WSSe is comparable to WS2 and WSe2 so-called „darkish” materials, in which the excitonic ground state is optically inactive. The energy range of emission lines which correspond to excitionic complexes apparent in WSSe is similar to WS2 and WSe2. These two materials are known for their excellent valley polarisation due to the strong spin−orbit coupling and WSSe is expected to be the same.

With the development of energy storage devices, the demand for flexible energy storage devices is increasing. In this study, flexible carbon nanotubes (CNTs) film is used as the substrate, flexible Ni-BTA@CNTs composite film is fabricated by a hydrothermal method and investigated as a cathode material for Zinc ion battery. Ni-BTA is formed by active organic ligands and metal ions through coordinate bonds. Its porous structure and high electrical conductivity are beneficial to the rapid transport of Zinc ions. In addition, CNTs film provides flexibility and long-range conductivity. Based on this, flexible Ni-BTA@CNTs composite film possesses a high specific capacity (203.8 mAh g^-1 at 0.1 A g^-1) and long cycle durability (after 600 cycles with a capacity retention of 78 %), and indicates the application potential in flexible Zinc ion storage devices.

Novel fluorescent nanocomposites (NCs) were generated using ions of Au(III), Ag(I), Fe(II) in conjunction with bovine serum albumin (BSA). BSA served as a template and simultaneously as a reducing agent. Au(III) was selected for the formation of fluorescent AuNCs in the presence of BSA (1); Ag(I) was employed in order to enhanced fluorescence intensity of NCs (2); and Fe ions were chosen as precursors for the formation of a contrast agent being employed in ¹H magnetic resonance imaging (MRI) (3). Two molar ratios of Au and Ag ions used in the course of the synthesis of NCs substantially influenced NCs fluorescence intensity, as well as the characteristic fluorescence peak position. On the other hand, it was revealed that Fe ions did not affect position of fluorescence peak maximum and had only a slightly negative effect on the fluorescence intensity of NCs with metal cations molar ratio of 5-1-1 (whereas no iron ions effect on fluorescence intensity was observed for the ratio of 5-2-2). At sufficiently elevated Fe ions concentrations, these novel NCs can be used for MRI without significant fluorescence signal quenching.

Acknowledgement:

This research was funded by Grant Agency of the Czech Republic, grant number 19-03207S, and Internal Grant Agency of Palacky University, grant number IGA_PrF_2021_017.

References:

(1) Xie, J.; Zheng, Y.; Ying, J. Y.; Protein-directed Synthesis of Highly Fluorescent Gold Nanoclusters. J. Am. Chem. Soc. 2009, 131,888−889

(2) Ganguly M.; Jana J.; Pal A.; Pal T.; Synergism of gold and silver invites enhanced fluorescence for practical applications.; RSC Adv., 2016, 6, 17683–17703

(3) An L.; Yan Ch.; Mu X.; Tao Ch.; Tian Q.; Lin J.; Yang S.; Paclitaxel-Induced Ultrasmall Gallic Acid-Fe@BSA Self-Assembly with Enhanced MRI Performance and Tumor Accumulation for Cancer Theranostics.; ACS Appl. Mater. Interfaces 2018, 10, 28483−28493

Nervous tissue regeneration represents a huge challenge in tissue engineering and therefore, numerous strategies are being investigated for this purpose. Current approaches are focused on the use of magnetic biomaterials to support nerve regeneration, since magnetic field was proved to have a beneficial effect on neuronal differentiation. Our aim was to develop and investigate the cytocompatibility and potential of natural-based materials enriched with magnetic nanoparticles (MNPs) to support the growth, viability and proliferation of neural stem cells (represented by NE-4C cell line, CRL-2925, ATCC). These composites were developed using electrospinning technique and were enriched with different concentration of MNPs (0.5% -2%, to be compared to a pure fish gelatin control material) then they were seeded with NE-4C cells and maintained in standard culture conditions for up to seven days. Cell viability and proliferation were tested using the MTT assay, while eventual cytotoxic effects were evaluated based on lactic dehydrogenase (LDH) release in culture medium. The proportion of live and dead cells in contact with MNPs-enriched scaffolds was revealed using Live/Dead assay. Investigation of changes in cytoskeleton distribution and focal adhesion assembly was observed by immunolabeling and confocal microscopy. Our results indicated that all tested scaffolds proved to be biocompatible with neural stem cells and didn’t induce any significant cytotoxic effects for up to one week of in vitro culture. MNPs concentration influenced proportionally the rate of cell growth and proliferation, while cytoskeleton immunolabeling revealed an elongated profile of actin microfilaments and emphasized focal adhesion kinase distribution, suggesting beneficial effects of MNPs-enriched composites. Thus, biomaterials embedding low concentrations of MNPs display good interaction with neural stem cells and could be used in further studies for nervous tissue regeneration. This work was supported by PN-III-P1-1.1-TE-2019-1191/MAGNIFICENT grant.

Silver nanoparticles were deposited on ZnO nanocolumns (Ag-NP@ZnO-NC) by two different laser-assisted approaches: photodecoration method were separately the Ag NPs are synthesized and then deposited over ZnO NCs under a laser-irradiated solution and photogrowthing method which the Ag NPs were simultaneously photoreduced and photodeposited over the ZnO NCs. Irradiation time ranged between 15 and 60 min were studied. Surface-Enhanced Raman spectroscopy measurements of Ag-NP@ZnO-NC substrates were evaluated with Rhodamine 6G as an analyte. The size and density of AgNPs were affected the irradiation time.For photodecorated devices, the SERS intensity increases as the deposition time increases and for photogrown substrates, a contrary behavior was observed. Substrates manufactured by photogrowthing method were found as the best SERS substrates with a 5-fold times signal enhancement compared with devices obtained by photodecoration. Under the experimental optimized conditions is obtained with a limit of detection up to 10−6 M for Rhodamine 6G (R6G).

In this work, silver nanostars were synthesized using silver nitrate, ascorbic acid and PVP, in a molar ratio of 3.6:71.5:X, respectively. Where x is the concentration of PVP which varied from 0.1 to 10 mM. The behavior of morphology and size of the nanostars was studied by scanning electron microscopy and UV-Vis absorption. In addition, SERS substrates were fabricated depositing silver nanostars over copper film in order to determine which morphology and size offer the lowest detection limit of methylene blue and crystal violet. These studies allow us to identify nanostars as an excellent nanostructure for the fabrication of ultrasensitive SERS substrates for the detection of persistent organic pollutants.

Abstract. N-(phosphonomethyl)glycine (glyphosate) represents a broad-spectrum systemic herbicide and crop desiccant. The ecological risks include potential risk to terrestrial and aquatic plants and birds, and low toxicity to honeybees. It is frequently detected at low levels in both urban and rural surface waters. Efficient technologies are currently unavailable for glyphosate removal from waters. SBA-3 mesoporous silica-based material was synthesized and studied for the glyphosate removal from water. The obtained silica material was characterized by FTIR, SEM, TG, BET surface area and pore size distribution measurements. In order to elucidate specific interactions between the mesoporous silica and glyphosate via phosphoric group, a surface functionalization with (3-aminopropyl)triethoxysilane was performed. It was observed a quantitative adsorption and a complete recovery of the adsorbent, which can be regenerated and reused with unaltered performances for at least five cycles.

Acknowledgements: The work has been funded by the Romanian Ministry of Research, Innovation and Digitalization, NUCLEU Program-Financing Contract no. 9N/2019, under Project PN 19 11 03 01 “Studies on the obtaining and improvement of the acido-basic properties of the nanoporous catalytic materials for application in wastes valorization”.

In this study, the catalytic performance of Photo-Fenton and sono-Fenton processes were tested on Acibenzolar-S-methyl fungicide. UV light source and ultrasound irradiation source (20 kHz of the frequency with a maximum of 125W power output) were used for Fenton-based reaction. The sono-Fenton process is the most effective in ASM degradation with a 100% degradation rate within 20 min compared to photo-Fenton, Fenton, photolysis, and sonolysis processes that achieved only 90%, 52%, 43% and 19%, respectively. The investigation shows that ultrasound irradiation has accelerated the efficiency of the Fenton process by increasing the hydroxyl radicals •OH generation. The kinetic study was carried out under different pH conditions, ferrous ions concentration and hydrogen peroxide dosages. The result showed that the optimum condition for acibenzolar-s-methyl degradation is at acidic pH medium, low concentration of hydrogen peroxide and ferrous ions. The contaminant was monitored with high-performance liquid chromatography. A transformation mechanism pathway of the sonochemical oxidation was suggested based on gas chromatography/mass spectra analysis.

Radiotherapy (RT) is a therapeutic modality that deliver a precise dose of ionizing radiation in a specific tumour volume, promoting the irradiation of tumor cells with as minimal damage as possible in surrounding normal tissues.⁽¹⁾ Besides the evolution of equipment and technology, this therapy still has some problems related with radioresistance, which consequently increase the recurrence at 5 years.^(2,3) Over the years, gold nanoparticles (AuNP) have attracted a lot of interest in cancer therapies due their unique chemical, optical and physical properties.^(4,5)

So, it was synthetized two different types of AuNPs – spherical (AuNP_sp) and rods (AuNP_r) for treat human prostate cancer cell line (PC3) and it was observed cell behavior when treated cells were irradiated with three fractions of 2,5 Gy. AuNPs were characterized using UV-Vis and TEM to confirm their size and shape. After, cells were treated with different concentrations of AuNPs from 0 to 1.0 mM during 24h. The results showed that none of the forms of AuNPs show signals of cytotoxicity until 1.0 mM, with exception of 1mM of AuNP_r, where cells exhibit cytotoxicity around ~10%. Taken all together, AuNP_sp and AuNP_r demonstrated be effective to reduce the cell viability when associated to RT. Comparing both structures, AuNP_r demonstrated a higher dose-dependency with and without radiation and under irradiation the inhibition of cell growth is higher when compared to control (no treatment). These results demonstrate for the first time the possibility of different forms of AuNPs can be used as potential radiosensitizer for prostate cancer cells.

Air pollution is a source of exogenous oxidative stress to which we are daily exposed, leading to a local or even systemic inflammatory status. The chronic exposure to oxidants such as ozone can result in tissue damage including skin conditions. To improve the natural immune defense, counteracting disorders induced by air pollution, natural antioxidants such as mangiferin can be employed. Indeed mangiferin is a natural glucosyl xanthone possessing an antioxidant and anti-inflammatory activity, potentially suitable to prevent skin diseases exacerbation and/or development. In order to find a “green” strategy for transdermal administration of mangiferin, lipid based nanovesicular systems were produced and characterized. Particularly, a formulative study was conducted to design ethosomes. These nanosystems can be considered as a new generation of liposomes, being characterized by a similar composition, while possessing ethanol, able to improve vesicle malleability and cutaneous penetration. The effect of the addition of polysorbate 80 and/or poloxamer 407 to the ethosome composition was investigated on vesicles size distribution and morphology by photon correlation spectroscopy and transmission electron microscopy. To study the capability of ethosome formulations as delivery systems for mangiferin, encapsulation efficiency and in vitro diffusion parameters were evaluated by Franz cells. Mean diameter of vesicles was affected by phosphatidylcholine concentration and by the presence of polysorbate or poloxamer, ranging between 200 and 550 nm. A multilamellar supramolecular structure was detectable in the case of ethosome, in the presence or in the absence of polysorbate or poloxamer. The diffusion kinetic of mangiferin was faster in the case of ethosomes produced in the presence of polysorbate 80. Furthermore, 3D human skin models exposed to ozone enabled to demonstrate the antioxidant and anti-inflammatory effect of mangiferin containing ethosomes against pollutants, especially in the case of vesicles produced in the presence of polysorbate 80, suggesting their possible application to prevent and treat skin conditions associated to oxinflammatory mechanisms.