Surface Testing of Dental Biomaterials—Determination of Contact Angle and Surface Free Energy

The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens–Wendt, van Oss–Chaudhury–Good and Zisman’s methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m²), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m²). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.     

Characteristics of Cr-B Coatings Produced on Vanadis® 6 Tool Steel Using Laser Processing

The paper presents the results of a study of the microstructure, chemical composition, microhardness and corrosion resistance of Cr-B coatings produced on Vanadis 6 tool steel. In this study, chromium and boron were added to the steel surface using a laser alloying process. The main purpose of the study was to determine the impact of those chemical elements on surface properties. Chromium and boron as well as their mixtures were prepared in various proportions and then were applied on steel substrate in the form of precoat of 100 µm thickness. Depending on the type of precoat used and laser processing parameters, changes in microstructure and properties were observed. Coatings produced using precoat containing chromium and boron mixture were characterized by high microhardness (900 HV0.05–1300 HV0.005) while maintaining good corrosion resistance. It was also found that too low laser beam power contributed to the formation of cracks and porosity.     

Formation and Investigation of Physicochemical,Biological and Bacteriostatic Properties of Nanocomposite Foils Containing Silver Nanoparticles and Graphene Oxide in Hyaluronic Acid Matrix

Natural polysaccharides, including hyaluronic acid, find a wide range of applications in biomedical sciences. There is a growing interest in nanocomposites containing hyaluronic acid and nanoparticles such as nanometals or graphene. In this study, we prepared foils of pure sodium hyaluronate and sodium hyaluronate containing nanosilver, graphene oxide, nanosilver/graphene oxide and characterized their properties. UV-vis spectroscopy and scanning electron microscopy (SEM) confirmed the formation of 10–20 nm silver nanoparticles. The structural changes were investigated using Fourier transforms infrared (FTIR) spectra and size exclusion chromatography. The obtained results suggest changes in molecular weights in the samples containing nanoparticles, which was highest in a sample containing nanosilver/graphene oxide. We also assessed the mechanical properties of the foils (thickness, tensile strength and elongation at break) and their wettability. The foils containing nanosilver and nanosilver/graphene oxide presented bacteriostatic activity against E. coli, Staphylococcus spp. and Bacillus spp., which was not observed in the control and sample containing graphene oxide. The composites containing graphene oxide and nanosilver/graphene oxide exhibited a cytotoxic effect on human melanoma WM266-4 cell lines (ATCC, Manassas, VA, USA).     

Probing nanoparticle translocation across the permeable endothelium in experimental atherosclerosis

Therapeutic and diagnostic nanomaterials are being intensely studied for several diseases, including cancer and atherosclerosis. However, the exact mechanism by which nanomedicines accumulate at targeted sites remains a topic of investigation, especially in the context of atherosclerotic disease. Models to accurately predict transvascular permeation of nanomedicines are needed to aid in design optimization. Here we show that an endothelialized microchip with controllable permeability can be used to probe nanoparticle translocation across an endothelial cell layer. To validate our in vitro model, we studied nanoparticle translocation in an in vivo rabbit model of atherosclerosis using a variety of preclinical and clinical imaging methods. Our results reveal that the translocation of lipid–polymer hybrid nanoparticles across the atherosclerotic endothelium is dependent on microvascular permeability. These results were mimicked with our microfluidic chip, demonstrating the potential utility of the model system.Improving the design of nanomedicines is key for their success and ultimate clinical application (1). The accumulation of such therapeutic or diagnostic nanomaterials primarily relies on enhanced endothelial permeability of the microvasculature in diseased tissue (2). This holds true for a wide range of pathological conditions, including inflammation, atherosclerosis, and most notably, oncological disease (3–6). Although attributed to the enhanced permeability and retention (EPR) effect, the exact mechanism by which nanoparticles accumulate in tumors continues to be a topic of research (7, 8). The “leaky” vasculature of tumors, which facilitates the extravasation of nanoparticles from microvessels (9), is a heterogeneous phenomenon that varies between different tumor models and even more so in patients. Moreover, the exploitation of nanomedicines in other conditions with enhanced microvessel permeability has only recently begun to be studied in detail. For example, in the last 5 y, a small but increasing number of preclinical studies that apply nanoparticle therapy in atherosclerosis models has surfaced (10). Although several targeting mechanisms have been proposed (4), the exact mechanism by which nanoparticles accumulate in atherosclerotic plaques remains to be investigated, but is likely facilitated by highly permeable neovessels that penetrate into the plaque from the vasa vasorum (Fig. 1A), a network of microvessels that supplies the wall of larger vessels (11).Open in a separate windowFig. 1.Development of an endothelialized microfluidic device to probe nanoparticle translocation over a permeable microvessel. (A) Schematics of continuous normal capillaries surrounding the vessel wall as well as permeable capillaries that penetrate into the atherosclerotic plaque from the vasa vasorum. (B) Schematic of an endothelialized microfluidic device that consists of two-layer microfluidic channels that are separated by a porous membrane (3 μm pore) on which ECs are grown. (C) TEER was dynamically measured across the endothelial layer on the membrane between the upper and lower channels. (D) A well-established monolayer of the microvascular endothelium is formed at TEER ∼400 (Ω·cm²). (E) The monolayer becomes highly permeable when stimulated with the inflammatory mediator, TNF-α, as well as with shear stress, with disruption of intercellular junctional structures (i.e., adherens junctions) between ECs, as evidenced by patchy expression of VE–cadherin (green) in the image on the right versus the left. Blue depicts nuclei stained with DAPI. (Scale bar, 20 μm.) (F) FITC–albumin translocation through the endothelial monolayer increases when the chip is treated with TNF-α. (G) The chip with endothelium cultured in different culture media [base, +FBS, +growth factors (GFs)] for 6 h shows a decrease in TEER with increased FITC–albumin translocation. No cell indicates the membrane only. TEER was normalized to the level with no cells (membrane only). (H) Schematic and TEM image of PEGylated lipid-coated nanoparticles encapsulating PLGA-conjugated AuNCs and Cy5.5. The average size was 69.7 ± 14 nm, which was measured from TEM images. (Scale bar, 100 nm.) Details on labeling, synthesis, characterization, and large-scale production procedures can be found in Materials and Methods and Fig. S2.Advances in biomedical imaging allow the study of plaque-targeting nanoparticles in a dynamic fashion with exceptional detail (12, 13). Microchip technology has the potential to monitor nanoparticle behavior at the (sub)cellular level. Microfluidic chips in which endothelial cells (ECs) are grown in the channels can serve as unique in vitro test systems to study microvascular function and associated disorders (14–18). They allow the isolation of specific biological hallmarks relevant to nanoparticle accumulation, such as the leaky endothelium. In the current study, we validate the potential utility of our microchip technology to study nanoparticle translocation over the endothelium and combine this with in vivo and ex vivo multimodality imaging studies on a rabbit model to better understand nanoparticle targeting of atherosclerotic plaques.     

A single nucleotide polymorphism −35 kb T > C (rs9264942) is strongly associated with psoriasis vulgaris depending on HLA-Cw06

HLA class I molecules play a role both in viral infection control and in autoimmune diseases development. rs9264942T > C polymorphism in HLA-C gene was found to impact on HLA-C surface expression level and to be associated with HIV-1 control. It was found that these HLA alleles which protect against AIDS are associated with autoimmune disease e.g. psoriasis vulgaris (PsV). Whether rs9264942 SNP is associated with PsV was investigated here. rs9264942T > C was genotyped in 292 PsV patients, and 254 controls using TaqMan Genotyping Assay.     

Increased Concentration of C-Reactive Protein in Obese Patients with Type 2 Diabetes Is Associated with Obesity and Presence of Diabetes but Not with Macrovascular and Microvascular Complications or Glycemic Control

The purpose of this study was to assess the concentration of C-reactive protein (CRP) in obese type 2 diabetes mellitus (DM2) patients and its association with macrovascular and microvascular complications. The study group consisted of 80 obese DM2 patients, including 20 macrovascular, 20 microvascular, 20 both macrovascular and microvascular, and 20 with no complications patients. The control group comprised 40 normoglycemic subjects—20 obese and 20 of normal body weight. Highly sensitive CRP and metabolic control parameters were assessed. CRP levels in obese diabetes subgroups and normoglycemic obese were similar and significantly higher than those in nonobese controls. No correlation was found between CRP and diabetes control parameters. There was a strong positive correlation between CRP level and body mass index in all groups. A multivariate analysis showed that DM2 and obesity are independent factors increasing CRP levels. Increased concentration of CRP in obese DM2 patients is related to obesity and diabetes itself. The lack of association between CRP and vascular complications remains unclear.     

Study of Nano h-BN Impact on Lubricating Properties of Selected Oil Mixtures

Our experiments aimed to study the influence of layered materials with nanometric-scale particles, which are part of lubricant oils, on their tribological properties. The object of this study was a lubricant oil made using base oil PAO4, which contained nanoparticle hexagonal boron nitride (nano h-BN) and a dispersant based on succinic acid imide. Comparative tests for engine oil (CB30) were also performed. The paper presents the method of preparing the test material and the tribological test results, including wear spot diameter (wear mark), limit wear load, and seizure load. The test results obtained demonstrate that nano-hexagonal boron nitride improves the tribological properties of lubricant oils. However, oil preparation and the quantitative selection of components markedly influence the results.     

Selective and efficient catalytic and photocatalytic oxidation of diphenyl sulphide to sulfoxide and sulfone: the role of hydrogen peroxide and TiO2 polymorph

In this paper, we describe the role of anatase and rutile crystal phases on diphenyl sulphide (Ph₂S) catalytic and photocatalytic oxidation. The highly selective and efficient synthesis of diphenyl sulfoxide (Ph₂SO) and diphenyl sulfone (Ph₂SO₂) at titanium dioxide was demonstrated. Ph₂S oxidation in the presence of hydrogen peroxide at anatase-TiO₂ can take place both as a catalytic and photocatalytic reaction, while at rutile-TiO₂ only photocatalytic oxidation is possible. The reaction at anatase leads mainly to Ph₂SO₂, whereas, in the presence of rutile a complete conversion to Ph₂SO is achieved after only 15 min (nearly 100% selectivity). Studies on the mechanistic details revealed a dual role of H₂O₂. It acts as a substrate in the reaction catalysed only by anatase, but it also plays a key role in alternative photocatalytic oxidation pathways. The presented study shows the applicability of photocatalysis in efficient and selective sulfoxide and sulfone production.

Selective sulfoxide and sulfone production can be precisely controlled by choosing TiO₂ polymorph and the reaction mode (catalysis versus photocatalysis).     

Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar

The amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was to evaluate the effect of sewage sludge ash (SSA) on the hydration heat process of cement mortars. The heat of the hydration of cement mortars was monitored by the isothermal calorimetric method for 7 days at 23 °C. The analysis of chemical composition and particle size distribution was performed on the tested material. The tests carried out have shown that SSA particles have irregular grain morphology and, taking into account the chemical composition consists mainly of oxides such as CaO, P₂O₅, SiO₂ and Al₂O₃. The concentration of these compounds affects the hydration process of cement mortars doped with SSA. In turn, the content of selected heavy metals in the tested ash should not pose a threat to the environment. Calorimetric studies proved that the hydration process is influenced by the presence of SSA in cement mortars. The studies showed that the rate of heat generation decreased (especially in the initial setting period) with the increasing replacement of cement by SSA, which also reduced the amount of total heat compared to the control cement mortar. With increasing mass of the replacement of cement with SSA up to 20%, the 7-day compressive strength of the mortar samples decreases.