Hydrogel-Inducing Graphene-Oxide-Derived Core-Shell Fiber Composite for Antibacterial Wound Dressing.

The study reveals the polymer-crosslinker interactions and functionality of hydrophilic nanofibers for antibacterial wound coatings. Coaxial electrospinning leverages a drug encapsulation protocol for a core-shell fiber composite with a core derived from polyvinyl alcohol and polyethylene glycol with amorphous silica (PVA-PEG-SiO2), and a shell originating from polyvinyl alcohol and graphene oxide (PVA-GO). Crosslinking with GO and SiO2 initiates the hydrogel transition for the fiber composite upon contact with moisture, which aims to optimize the drug release. The effect of hydrogel-inducing additives on the drug kinetics is evaluated in the case of chlorhexidine digluconate (CHX) encapsulation in the core of core-shell fiber composite PVA-PEG-SiO2-1x-CHX@PVA-GO. The release rate is assessed with the zero, first-order, Higuchi, and Korsmeyer-Peppas kinetic models, where the inclusion of crosslinking silica provides a longer degradation and release rate. CHX medicated core-shell composite provides sustainable antibacterial activity against Staphylococcus aureus.

Design of an Artificial Opal/Photonic Crystal Interface for Alcohol Intoxication Assessment: Capillary Condensation in Pores and Photonic Materials Work Together.

Alcohol intoxication has a dangerous effect on human health and is often associated with a risk of catastrophic injuries and alcohol-related crimes. A demand to address this problem adheres to the design of new sensor systems for the real-time monitoring of exhaled breath. We introduce a new sensor system based on a porous hydrophilic layer of submicron silica particles (SiO2 SMPs) placed on a one-dimensional photonic crystal made of Ta2O5/SiO2 dielectric layers whose operation relies on detecting changes in the position of surface wave resonance during capillary condensation in pores. To make the active layer of SiO2 SMPs, we examine the influence of electrostatic interactions of media, particles, and the surface of the crystal influenced by buoyancy, gravity force, and Stokes drag force in the frame of the dip-coating preparation method. We evaluate the sensing performance toward biomarkers such as acetone, ammonia, ethanol, and isopropanol and test sensor system capabilities for alcohol intoxication assessment. We have found this sensor to respond to all tested analytes in a broad range of concentrations. By processing the sensor signals by principal component analysis, we selectively determined the analytes. We demonstrated the excellent performance of our device for alcohol intoxication assessment in real-time.

Plasma modification of carbon nanowalls induces transition from superhydrophobic to superhydrophilic.

Graphene-based materials play an essential role in a wide range of modern technologies due to their surface properties such as adsorption capacity and controllable wettability, which depend on the production methods. For practical applications, it is crucial to control the surface properties to achieve the desired wetting characteristics, which can be described with the contact angle (CA). Here, we experimentally investigate the wettability properties of the carbon nanowalls and show how to manage a wetting transition from superhydrophobic to superhydrophilic states. A CA of 170° was reached with direct plasma synthesis, while an angle smaller than 20° was achieved during the atmosphere plasma modification. Combining the formation of the surface groups due to the plasma treatment results and the macroscale wetting behavior in terms of the Cassie-Baxter model, we qualitatively explain how the observed wetting enhancement is induced by both controlled chemical and geometrical surface-heterogeneity.

Photoluminescence of Two-Dimensional MoS2 Nanosheets Produced by Liquid Exfoliation.

Extraordinary properties of two-dimensional materials make them attractive for applications in different fields. One of the prospective niches is optical applications, where such types of materials demonstrate extremely sensitive performance and can be used for labeling. However, the optical properties of liquid-exfoliated 2D materials need to be analyzed. The purpose of this work is to study the absorption and luminescent properties of MoS2 exfoliated in the presence of sodium cholate, which is the most often used surfactant. Ultrasound bath and mixer-assisted exfoliation in water and dimethyl sulfoxide were used. The best quality of MoS2 nanosheets was achieved using shear-assisted liquid-phase exfoliation as a production method and sodium cholate (SC) as a surfactant. The photoluminescent properties of MoS2 nanosheets varied slightly when changing the surfactant concentrations in the range C(SC) = 0.5-2.5 mg/mL. This work is of high practical importance for further enhancement of MoS2 photoluminescent properties via chemical functionalization.

The Impact of Commercially Available Dry Mouth Products on the Corrosion Resistance of Common Dental Alloys.

Dental implants are thought to be implanted for life, but throughout their lifespan, they function in aggressive oral environment, resulting in corrosion of the material itself as well as possible inflammation of adjacent tissues. Therefore, materials and oral products for people with metallic intraoral appliances must be chosen carefully. The purpose of this study was to investigate the corrosion behavior of common titanium and cobalt-chromium alloys in interaction with various dry mouth products using electrochemical impedance spectroscopy (EIS). The study showed that different dry mouth products lead to different open circuit potentials, corrosion voltages, and currents. The corrosion potentials of Ti64 and CoCr ranged from -0.3 to 0 V and -0.67 to 0.7 V, respectively. In contrast to titanium, pitting corrosion was observed for the cobalt-chromium alloy, leading to the release of Co and Cr ions. Based on the results, it can be argued that the commercially available dry mouth remedies are more favorable for dental alloys in terms of corrosion compared to Fusayama Meyer's artificial saliva. Thus, to prevent undesirable interactions, the individual characteristics of not only the composition of each patient's tooth and jaw structure, but also the materials already used in their oral cavity and oral hygiene products, must be taken into account.

Thermal and Electrical Properties of Additively Manufactured Polymer-Boron Nitride Composite.

The efficiency of electronic microchip-based devices increases with advancements in technology, while their size decreases. This miniaturization leads to significant overheating of various electronic components, such as power transistors, processors, and power diodes, leading to a reduction in their lifespan and reliability. To address this issue, researchers are exploring the use of materials that offer efficient heat dissipation. One promising material is a polymer-boron nitride composite. This paper focuses on 3D printing using digital light processing of a model of a composite radiator with different boron nitride fillings. The measured absolute values of the thermal conductivity of such a composite in the temperature range of 3-300 K strongly depend on the concentration of boron nitride. Filling the photopolymer with boron nitride leads to a change in the behavior of the volt-current curves, which may be associated with the occurrence of percolation currents during the deposition of boron nitride. The ab initio calculations show the behavior and spatial orientation of BN flakes under the influence of an external electric field at the atomic level. These results demonstrate the potential use of photopolymer-based composite materials filled with boron nitride, which are manufactured using additive techniques, in modern electronics.

Effect of Graphene Oxide and Nanosilica Modifications on Electrospun Core-Shell PVA-PEG-SiO2@PVA-GO Fiber Mats.

Electrospinning is a well-established method for the fabrication of polymer biomaterials, including those with core-shell nanofibers. The variability of structures presents a great range of opportunities in tissue engineering and drug delivery by incorporating biologically active molecules such as drugs, proteins, and growth factors and subsequent control of their release into the target microenvironment to achieve therapeutic effect. The object of study is non-woven core-shell PVA-PEG-SiO2@PVA-GO fiber mats assembled by the technology of coaxial electrospinning. The task of the core-shell fiber development was set to regulate the degradation process under external factors. The dual structure was modified with silica nanoparticles and graphene oxide to ensure the fiber integrity and stability. The influence of the nano additives and crosslinking conditions for the composite was investigated as a function of fiber diameter, hydrolysis, and mechanical properties. Tensile mechanical tests and water degradation tests were used to reveal the fracture and dissolution behavior of the fiber mats and bundles. The obtained fibers were visualized by confocal fluorescence microscopy to confirm the continuous core-shell structure and encapsulation feasibility for biologically active components, selectively in the fiber core and shell. The results provide a firm basis to draw the conclusion that electrospun core-shell fiber mats have tremendous potential for biomedical applications as drug carriers, photocatalysts, and wound dressings.

Sulfonimide-Based Dendrimers: Progress in Synthesis, Characterization, and Potential Applications.

There are more than 50 families of dendrimers, and some of which, such as polyamidoamine PAMAM, are well studied, and some are just starting to attract the attention of researchers. One promising type of dendrimers is sulfonimide-based dendrimers (SBDs). To date, SBDs are used in organic synthesis as starting reagents for the convergent synthesis of higher generations dendrimers, in materials science as alternative electrolyte solutions for fuel cells, and in medicinal chemistry as potential substances for drug transfer procedures. Despite the fact that most dendrimers are amorphous substances among the SBDs, several structures are distinguished that are prone to the formation of crystalline solids with melting points in the range of 120-250 °C. Similar to those of other dendrimers, the chemical and physical properties of SBDs depend on their outer shell, which is formed by functional groups. To date, SBDs decorated with end groups such as naphthyl, nitro, methyl, and methoxy have been successfully synthesized, and each of these groups gives the dendrimers specific properties. Analysis of the structure of SBD, their synthesis methods, and applications currently available in the literature reveals that these dendrimers have not yet been fully explored.