Ilana Perelshtein

We present here a one-pot hydrothermal synthesis of fluorescent carbon dots (CDs) using olive, rosemary, sage, and thyme leaves as a carbon source. The hydrothermal reaction was conducted at 180 °C for 12 h, thereby converting biomass into water-dispersible CDs without a passivating agent. The average size of the CDs, determined by TEM, was 3–6 nm, with a spherical morphology. All synthesized CDs displayed excitation-dependent fluorescence, with emission maxima at 400–440 nm (blue) with excitation at 340–370 nm. FLIM measurements yielded similar fluorescence lifetimes of approximately 5 ns in aqueous solutions of CDs. FTIR spectra indicated surface hydroxyl and nitrogen-containing functionalities that may contribute to photoluminescence. The antibacterial activity of the as-synthesized CDs against a panel of Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Listeria innocua, Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant S. aureus (MRSA), multidrug-resistant (MDR) E. coli, and Klebsiella pneumoniae (MDR)) was investigated. It was shown that biomass-derived CDs exhibit antibacterial activity, being more effective against Gram-positive bacteria, with MIC values as low as 0.625 mg/mL for olive-, rosemary-, and thyme-derived CDs against S. aureus and MRSA. These findings suggest that the developed CDs are fluorescent materials offering viable possibilities in biomedical research, as well as antimicrobial agents.

Nanomaterials (NMs), including nanoparticles (NPs), offer promising potential in achieving the European Commission’s Green Deal goals of climate-neut

Catheter-associated urinary tract infections (CAUTI) are among the most common bacterial infections associated with prolonged hospitalization and increased healthcare expenditures. Despite recent advances in the prevention and treatment of these infections, there are still many challenges remaining, among them the creation of a durable catheter coating, which prevents bacterial biofilm formation. The current work reports on a method of protecting medical tubing endowed with antibiofilm properties. Silicone catheters coated sonochemically with ZnO nanoparticles (NPs) demonstrated excellent antibiofilm effects. Toward approval by the European Medicines Agency, it was realized that the ZnO coating would not withstand the regulatory requirements of avoiding dissolution for 14 days in artificial urine examination. Namely, after exposure to urine for 14 days, the coating amount was reduced by 90%. Additional coatings with either carbon or silica maintained antibiofilm activity against Staphylococcus aureus while resisting dissolution in artificial urine for 14 days (C- or SiO₂-protected catheters exhibited only 29% reduction). HR-SEM images of the protected catheters indicate the presence of the ZnO coating as well as the protective layer. Antibiofilm activity of all catheters was evaluated both before and after exposure to artificial urine. It was shown that before artificial urine exposure, all coated catheters showed high antibiofilm properties compared to the uncoated control. Exposure of ZnO-coated catheters, without the protective layer, to artificial urine had a significant effect exhibited by the decrease in antibiofilm activity by almost 2 orders of magnitude, compared to unexposed catheters. Toxicity studies performed using a reconstructed human epidermis demonstrated the safety of the improved coating. Exposure of the epidermis to ZnO catheter extracts in artificial urine affects tissue viability compared with control samples, which was not observed in the case of ZnO NPs coating with SiO₂ or C. We suggest that silica and carbon coatings confer some protection against zinc ions release, improving ZnO coating safety.

In this paper, the properties, mineral magnetic modification, and beneficiation of tailings from the central mining and processing plant in Kryvyi Rih, Ukraine, have been studied. Samples were investigated by X-ray diffraction, X-ray fluorescence, microscopy, and magnetization measurements. The beneficiation was conducted using magnetizing roasting with carbon monoxide followed by dry low-intensity magnetic separation. The effects of chemical, mineral, and granulometric composition on the processing of fine tailings of different sizes sampled at different points of the tailings pond were investigated. Additionally, we proposed a new approach for magnetic separation of fine magnetically modified tailings based on the combination of permanent and alternating magnetic fields. Magnetizing roasting resulted in an enhancement in mass magnetization to 11–62 Am²/kg in comparison with initial values of 0.3–1.5 Am²/kg. After magnetic separation, the magnetic concentrates consisted almost completely of magnetite (with the magnetization of 75–88 Am²/kg) and non-magnetic residues contained major quartz. The content of iron in magnetic concentrates reached 68.5–70.2 wt.% and iron recovery 77–96 wt.%, depending on size fraction. We could conclude that the tailings are represented by fine-grained liberated material that can be effectively upgraded using magnetizing roasting and magnetic separation into two valuable products, such as iron concentrate and quartz powder.

In the last few decades, point-of-care (POC) sensors have become increasingly important in the detection of various targets for the early diagnostics and treatment of diseases. Diverse nanomaterials are used as building blocks for the development of smart biosensors and magnetite nanoparticles (MNPs) are among them. The intrinsic properties of MNPs, such as their large surface area, chemical stability, ease of functionalization, high saturation magnetization, and more, mean they have great potential for use in biosensors. Moreover, the unique characteristics of MNPs, such as their response to external magnetic fields, allow them to be easily manipulated (concentrated and redispersed) in fluidic media. As they are functionalized with biomolecules, MNPs bear high sensitivity and selectivity towards the detection of target biomolecules, which means they are advantageous in biosensor development and lead to a more sensitive, rapid, and accurate identification and quantification of target analytes. Due to the abovementioned properties of functionalized MNPs and their unique magnetic characteristics, they could be employed in the creation of new POC devices, molecular logic gates, and new biomolecular-based biocomputing interfaces, which would build on new ideas and principles. The current review outlines the synthesis, surface coverage, and functionalization of MNPs, as well as recent advancements in magnetite-based biosensors for POC diagnostics and some perspectives in molecular logic, and it also contains some of our own results regarding the topic, which include synthetic MNPs, their application for sample preparation, and the design of fluorescent-based molecular logic gates.

Magnetite nanoparticles with different surface coverages are of great interest for many applications due to their intrinsic magnetic properties, nanometer size, and definite surface morphology. Magnetite nanoparticles are widely used for different medical-biological applications while their usage in optics is not as widespread. In recent years, nanomagnetite suspensions, so-called magnetic ferrofluids, are applied in optics due to their magneto-optical properties. This review gives an overview of nanomagnetite synthesis and its properties. In addition, the preparation and application of magnetic nanofluids in optics, nanophotonics, and magnetic imaging are described.

This study aims to investigate the effects of a novel ZnCuO nanoparticle coating for dental implants—versus those of conventional titanium surfaces—on bacteria and host cells. A multispecies biofilm composed of Streptococcus sanguinis, Actinomyces naeslundii, Porphyromonas gingivalis, and Fusobacterium nucleatum was grown for 14 days on various titanium discs: machined, sandblasted, sandblasted and acid-etched (SLA), ZnCuO-coated, and hydroxyapatite discs. Bacterial species were quantified with qPCR, and their viability was examined via confocal microscopy. Osteoblast-like and macrophage-like cells grown on the various discs for 48 h were examined for proliferation using an XTT assay, and for activity using ALP and TNF-α assays. The CSLM revealed more dead bacteria in biofilms grown on titanium than on hydroxyapatite, and less on sandblasted than on machined and ZnCuO-coated surfaces, with the latter showing a significant decrease in all four biofilm species. The osteoblast-like cells showed increased proliferation on all of the titanium surfaces, with higher activity on the ZnCuO-coated and sandblasted discs. The macrophage-like cells showed higher proliferation on the hydroxyapatite and sandblasted discs, and lower activity on the SLA and ZnCuO-coated discs. The ZnCuO-coated titanium has anti-biofilm characteristics with desired effects on host cells, thus representing a promising candidate in the complex battle against peri-implantitis.

There is a huge demand for materials capable of simple detection or separation after conjugation with specific biologic substances when applied as a diagnostic tools. Taking into account the photoluminescence properties of C-dots and the highly magnetic properties of Fe(0), a new hybrid composite of these components was synthesized via ultrasound irradiation. The material was fully characterized by various physicochemical techniques. The main goal of the current study was to obtain a highly magnetic and intense fluorescent hybrid material. The goal was achieved. In addition, magnetic particles tended to agglomerate. The new hybrid can be suspended in ethanol, which is an additional feature of the current research. The dispersion of the hybrid nanoparticles in ethanol was achieved by utilizing the interaction of iron particles with C-dots which were decorated with functional groups on their surface. The newly formed hybrid material has potential applications in diagnostic by conjugating with specific antibodies or with any other biologic compounds. Such application may be useful in detection of various diseases such as: cancer, tuberculosis, etc.