Joanna Mystkowska

Bactericidal activity and biocompatibility of ceragenin-coated magnetic nanoparticles

BackgroundCeragenins, synthetic mimics of endogenous antibacterial peptides, are promising candidate antimicrobial agents. However, in some settings their strong bactericidal activity is associated with toxicity towards host cells. To modulate ceragenin CSA-13 antibacterial activity and biocompatibility, CSA-13-coated magnetic nanoparticles (MNP-CSA-13) were synthesized. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize MNP-CSA-13 physicochemical properties. Bactericidal action and ability of these new compounds to prevent Pseudomonas. aeruginosa biofilm formation were assessed using a bacteria killing assay and crystal violet staining, respectively. Release of hemoglobin from human red blood cells was measured to evaluate MNP-CSA-13 hemolytic activity. In addition, we used surface activity measurements to monitor CSA-13 release from the MNP shell. Zeta potentials of P. aeruginosa cells and MNP-CSA-13 were determined to assess the interactions between the bacteria and nanoparticles. Morphology of P. aeruginosa subjected to MNP-CSA-13 treatment was evaluated using atomic force microscopy (AFM) to determine structural changes indicative of bactericidal activity.ResultsOur studies revealed that the MNP-CSA-13 nanosystem is stable and may be used as a pH control system to release CSA-13. MNP-CSA-13 exhibits strong antibacterial activity, and the ability to prevent bacteria biofilm formation in different body fluids. Additionally, a significant decrease in CSA-13 hemolytic activity was observed when the molecule was immobilized on the nanoparticle surface.ConclusionOur results demonstrate that CSA-13 retains bactericidal activity when immobilized on a MNP while biocompatibility increases when CSA-13 is covalently attached to the nanoparticle.

Magnetic nanoparticles as a drug delivery system that enhance fungicidal activity of polyene antibiotics

This study was designed to assess the antifungal/anti-biofilm and hemolytic properties of two polyene antibiotics, amphotericin B (AMF) and nystatin (NYS), attached to the surface of magnetic nanoparticles (MNP) against clinical isolates of Candida species and human red blood cells, respectively. The developed nanosystems, MNP@AMF and MNP@NYS, displayed stronger fungicidal activity than unbound AMF or NYS. Synergistic activity was observed with a combination of polyenes and MNPs against all tested Candida strains. Nanosystems were more potent than unbound agents when tested against Candida strains in the presence of pus, and as agents able to prevent Candida biofilm formation. The observed inactivation of catalase Cat1 in Candida cells upon treatment with the nanosystems suggests that disruption of the oxidation-reduction balance is a mechanism leading to inhibition of Candida growth. The significant decrease of polyenes lytic activity against host cells after their attachment to MNPs surface indicates improvement in their biocompatibility.

Biocorrosion of 316LV steel used in oral cavity due to Desulfotomaculum nigrificans bacteria.

Corrosion processes of metallic biomaterials in the oral cavity pose a significant limitation to the life and reliable functioning of dental materials. In this article, the influence of environment bacteria Desulfotomaculum nigrificans sulfate reducing bacteria on the corrosion processes of 316LV steel was assessed. After 14 and 28 days of contact of the material with the bacterial environment, the surfaces of the tested biomaterial were observed by means of confocal scanning laser microscopy, and their chemical composition was studied using X-Ray Photoelectron Spectrometry and a scanning transmission electron microscopy. Corrosive changes, the presence of sulfur (with atomic concentration of 0.5%) on the surface of the biomaterial and the presence of a thin oxide layer (thickness of ∼20 nm) under the surface of the steel were observed. This corrosion layer with significant size reduction of grains was characterized by an increased amount of oxygen (18% mas., p < 0.001) in comparison to untreated 316LV steel (where oxygen concentration - 10% mas.). Image analysis conducted using APHELION software indicated that corrosion pits took up ∼2.8% of the total tested surface. The greatest number of corrosion pits had a surface area within the range of 100-200 μm2 .

Desorption electrospray ionization-based imaging of interaction between vascular graft and human body

The desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) is known as a fast and convenient MS-based method for lipid imaging in various biological materials. Here, we applied this technique to visualize lipid distribution in a vascular graft removed from a patients body. This is a good example of the DESI system capabilities toward imaging of interaction between artificial material and living tissues. Detailed analysis allowed for visualization of the spatial distribution of selected lipids in this implanted, artificial material. Not only DESI-MSI allowed visualization of lipid distribution in the investigated material but also enabled identification of the detected molecular species using MS/MS. Here, this technique was successfully used to evaluate the saturation and spatial distribution of endogenous lipids in the artificial vascular graft. Unambiguous identification of the lipids was done with the aid of fragmentation procedure. We also showed that various lipids localize preferably in graft material or internal plaque existing inside the graft.

Tribological Properties of Selected Self-Made Solutions of Synthetic Saliva

The present paper describes the results of tests on the influence of selected self-made solutions of synthetic saliva on tribological characteristics of implant materials on the example of the Co-Cr-Mo alloy. The used saliva substitutes were prepared on the basis of gums (xanthan, guar, arabic and carob bean) dissolved in saline buffer. Analysis of the values of the coefficient of friction and the wear of the tested dental alloy in tested solutions was performed. Different values of the coefficient of friction were observed for friction pairs tested in individual solutions. Its lowest values were achieved during tests using xanthan gum with SDS (sodium dodecyl sulfate) addition, and the highest values were achieved for xanthan gum. As regards wear analysis, its lowest value was registered during lubrication with natural saliva. Among saliva substitutes, the lowest value of mass wear of dental alloy was observed in solution of xanthan gum, and the highest value was registered for carob bean gum. After friction tests, elements of the friction pair were subjected to microscope analysis using the Olympus BX61 optical microscope.

The Role of Oral Cavity Biofilm on Metallic Biomaterial Surface Destruction–Corrosion and Friction Aspects

Metallic biomaterials in the oral cavity are exposed to many factors such as saliva, bacterial microflora, food, temperature fluctuations, and mechanical forces. Extreme conditions present in the oral cavity affect biomaterial exploitation and significantly reduce its biofunctionality, limiting the time of exploitation stability. We mainly refer to friction, corrosion, and biocorrosion processes. Saliva plays an important role and is responsible for lubrication and biofilm formation as a transporter of nutrients for microorganisms. The presence of metallic elements in the oral cavity may lead to the formation of electro-galvanic cells and, as a result, may induce corrosion. Transitional microorganisms such as sulfate-reducing bacteria may also be present among the metabolic microflora in the oral cavity, which can induce biological corrosion. Microorganisms that form a biofilm locally change the conditions on the surface of biomaterials and contribute to the intensification of the biocorrosion processes. These processes may enhance allergy to metals, inflammation, or cancer development. On the other hand, the presence of saliva and biofilm may significantly reduce friction and wear on enamel as well as on biomaterials. This work summarizes data on the influence of saliva and oral biofilms on the destruction of metallic biomaterials.

Biotribological properties of dentures lubricated with artificial saliva

This paper presents the results of tests on the effect of adsorbed films of saliva substitutes on the tribological characteristics of metal alloys based on the example of stainless steel 316LVM and two alloys, Co–Cr–Mo and Ti‒6Al–4V. Saliva substitutes were prepared based on animal mucin and xanthan gum dissolved in phosphate buffered saline (PBS). The adsorbed salivary films significantly reduced the coefficient of friction of the tested biomaterials. Low values of coefficient of friction have been achieved during the tests using PBS + mucin. The analysis of wear of tested materials showed lowest values in the process of friction using PBS + mucin + xanthan gum. An IR analysis of the studied surfaces confirmed the presence of wear marks on the adsorbed salivary films.

Fluoride Release and Antibacterial Activity of Self-Made Composite Materials for Dental Fillings

In the paper own prepared materials with addition fluorine sources were evaluated. The aim of the study was to assess the quality and quantity of fluoride source on fluoride ions release from composite materials. Antibacterial activity of analyzed materials in relation to four bacteria was investigated. Fluoride ions release was measured by direct potentiometry method with fluoride ion selective electrode. The measurements were carried out after 1, 4, 7, 14, 30, 60 days of storage in buffer at pH 6.8. The antibacterial activity of the materials was evaluated against standard bacterial strains using the agar diffusion test. Tests show that the highest level of fluoride ions emission was observed for composite with fluoridated glass (material A) on the seventh day of the study. Similar fluoride ions amount was released from material consisted of fluoridated glass and ytterbium fluoride (material C), but not until on the thirtieth day of the study. After 24 hours of composite bonding there was inhibition of bacterial growth by composite C, whereas composite A did not show similar activity. On the eighth day after polymerization, both materials were significantly more active towards two bacteria.

The Influence of Nano-Silica on the Wear Resistance of Ceramic – Polymer Composites Intended for Dental Fillings

Ceramic – polymer composites based on acrylic (bis–GMA) and urethane – methacrylate (UM) resins with a 60 % total volume fraction of filler consisting of micro particles of glass and nano-particles of silica were fabricated. The nano-silica contents were: 0, 10, 20 vol. %. The composite samples were subjected to wear tests using an occlusion simulator tester which applies reciprocating movement and cyclic loading on the test material. This method of testing provides some similarity to the masticatory pattern occurring in the mouth during eating. The enamel of a human tooth was used as a counter-sample. The coefficient of friction was determined and the wear resistance of the composite samples containing the various nano-silica contents was established. In addition, the relative influence of the composite composition on the rate of wear of the human tooth enamel was estimated. The results of the study indicate that the addition of nano-silica significantly improves the wear resistance of the ceramic – polymer composites and reduces the wear of enamel. It was found that the addition of nano-silica has no influence on the coefficient of friction. It was also established that composites based on UM resin show better wear resistance than those based on a mixture of bis-GMA and TEGDMA resin.

Assessment of aliphatic poly(ester-carbonate-urea-urethane)s potential as materials for biomedical application

Selected mechanical and biological properties of biodegradable elastomeric poly(ester-carbonate-urea-urethane)s (PECUUs) point towards their potential to be applied as scaffolds in tissue engineering. Here we explore their medical applicability taking into account their hemocompatibility and cytotoxicity. The influence of the ester monomer (derivatives of adipic and succinic acids), as well as diisocyanate type (IPDI and HDI) on the investigated PECUUs properties is presented. The presence of aliphatic diisocyanates, cyclic IPDI or linear HDI, governs the adhesion of Candida cells to these polymers offering the possibility to control the biofilm formation on their surface. In comparison to the linear form, cyclic diisocyanates with pentamethylene succinate or adipate fragments had two to three times lower biofilm mass formation on their surface. Reduced hemoglobin release from red blood cells observed during incubation of tested polymers with human erythrocytes suspension indicates their potential biocompatibility with human tissues. PECUUs were also able to support the growth of human keratinocytes HaCaT on their surface when coated with collagen. In effect, IPDI derivatives might possess a high potential for use in biomedical applications.