Maria Szymonowicz

The impact of the dibutyrylchitin molar mass on the bioactive properties of dressings used to treat soft tissue wounds

In this work, we describe a novel technique for producing biocompatible medical products with bioactive properties from the biodegradable polymer dibutyrylchitin (DBC). Materials produced by blowing out polymer solutions have excellent hemostaic properties and are easy to handle during surgery. Biocompatibility studies, encompassing hemostasis and the evaluation of post-implantation reactions, indicate that the biological properties of DBC depend on the molecular mass of the polymer. Lower molecular mass polymers are preferable for use in implanted wound dressings.

Biological Properties of Low-Toxic PLGA and PLGA/PHB Fibrous Nanocomposite Scaffolds for Osseous Tissue Regeneration. Evaluation of Potential Bioactivity

The aim of the study was to evaluate the biocompatibility and bioactivity of two new prototype implants for bone tissue regeneration made from biodegradable fibrous materials. The first is a newly developed poly(l-lactide-co-glycolide), (PLGA), and the second is a blend of PLGA with synthetic poly([R,S]-3-hydroxybutyrate) (PLGA/PHB). The implant prototypes comprise PLGA or PLGA/PHB nonwoven fabrics with designed pore structures to create the best conditions for cell proliferation. The bioactivity of the proposed implants was enhanced by introducing a hydroxyapatite material and a biologically active agent, namely, growth factor IGF1, encapsulated in calcium alginate microspheres. To assess the biocompatibility and bioactivity, allergenic tests and an assessment of the local reaction of bone tissue after implantation were performed. Comparative studies of local tissue response after implantation into trochanters for a period of 12 months were performed on New Zealand rabbits. Based on the results of the in vivo evaluation of the allergenic effects and the local tissue reaction 12 months after implantation, it was concluded that the two implant prototypes, PLGA + IGF1 and PLGA/PHB + IGF1, were characterized by high biocompatibility with the soft and bone tissues of the tested animals.

Cytotoxicity Evaluation of High-Temperature Annealed Nanohydroxyapatite in Contact with Fibroblast Cells

Biomaterials are substances manufactured for medical purposes in direct contact with the tissues of organisms. Prior to their use, they are tested to determine their usefulness and safety of application. Hydroxyapatites are used in medicine as a bony complement because of their similarity to the natural apatite therein. Thanks to their bioactivity, biocompatibility, stability and non-toxicity hydroxyapatite are the most commonly used materials in osteoimplantology. The use of materials at the nanoscale in medicine or biology may carry the risk of undesirable effects. The aim of the study was to evaluate the cytotoxic effect of high-temperature annealed nanohydroxyapatites on the L929 murine fibroblasts. Nanohydroxyapatites in powder form were obtained by the wet chemistry method: in the temperature range of 800–1000 °C and used for the study. Based on performed studies evaluating the morphology and fibroblast viability, it was found that nanohydroxyapatites show no cytotoxic effects on the L929 cell line.

Biological Properties of Low-Toxicity PLGA and PLGA/PHB Fibrous Nanocomposite Implants for Osseous Tissue Regeneration. Part I: Evaluation of Potential Biotoxicity

In response to the demand for new implant materials characterized by high biocompatibility and bioresorption, two prototypes of fibrous nanocomposite implants for osseous tissue regeneration made of a newly developed blend of poly(l-lactide-co-glycolide) (PLGA) and syntheticpoly([R,S]-3-hydroxybutyrate), PLGA/PHB, have been developed and fabricated. Afibre-forming copolymer of glycolide and l-lactide (PLGA) was obtained by a unique method of synthesis carried out in blocksusing Zr(AcAc)4 as an initiator. The prototypes of the implants are composed of three layers of PLGA or PLGA/PHB, nonwoven fabrics with a pore structure designed to provide the best conditions for the cell proliferation. The bioactivity of the proposed implants has been imparted by introducing a hydroxyapatite material and IGF1, a growth factor. The developed prototypes of implants have been subjected to a set of in vitro and in vivobiocompatibility tests: in vitro cytotoxic effect, in vitro genotoxicity and systemic toxicity. Rabbitsshowed no signs of negative reactionafter implantation of the experimental implant prototypes.

Influence of nanocrystalline structure and surface properties of TiO2 thin films on the viability of L929 cells

Abstract In this work the physicochemical and biological properties of nanocrystalline TiO2 thin films were investigated. Thin films were prepared by magnetron sputtering method. Their properties were examined by X-ray diffraction, photoelectron spectroscopy, atomic force microscopy, optical transmission method and optical profiler. Moreover, surface wettability and scratch resistance were determined. It was found that as-deposited coatings were nanocrystalline and had TiO2-anatase structure, built from crystallites in size of 24 nm. The surface of the films was homogenous, composed of closely packed grains and hydrophilic. Due to nanocrystalline structure thin films exhibited good scratch resistance. The results were correlated to the biological activity (in vitro) of thin films. Morphological changes of mouse fibroblasts (L929 cell line) after contact with the surface of TiO2 films were evaluated with the use of a contrast-phase microscope, while their viability was tested by MTT colorimetric assay. The viability of cell line upon contact with the surface of nanocrystalline TiO2 film was comparable to the control sample. L929 cells had homogenous cytoplasm and were forming a confluent monofilm, while lysis and inhibition of cell growth was not observed. Moreover, the viability in contact with surface of examined films was high. This confirms non-cytotoxic effect of TiO2 film surface on mouse fibroblasts.

Hemostatic, Resorbable Dressing of Natural Polymers-Hemoguard

Abstract Investigations are presented for the preparation of a model hemostatic dressing that would exhibit an adequate hemostatic capacity in injuries and surgical wounds, an antibacterial activity to prevent primary and secondary infections, and offer safety in use. The Hemoguard dressing has been designed as a powder prepared from the complex chitosan/alginate Na/Ca in the form of micro- and nano-fibrids. Useful antibacterial and hemostatic properties of Hemoguard, which would qualify the material as first aid dressing and a temporary protection of injury wounds in field conditions, were assessed. Biocompatibility of the dressing was confirmed by biological in vitro examinations.

Influence of surface modifications of a nanostructured implant on osseointegration capacity – preliminary in vivo study

In response to the need for implant materials characterized by high biocompatibility a new type of nanostructured Ti6Al7Nb implants for osseous tissue regeneration have been fabricated. The nanostructured cylindrical implants were manufactured in accordance with 3D CAD data using the Selective Laser Melting (SLM) method. Implants were subjected to chemical polishing using a mixture of nitric acid and fluoride (test group) as well as cleaned in distilled water and isopropyl alcohol (control group). The structural and morphological properties of the obtained samples were determined by using XRD (X-ray powder diffraction), TEM (transmission electron microscopy) and SEM (scanning electron microscopy) techniques. The particle size was verified and calculated by Rietveld method to be in the range of 25–90 nm. In the present study, experimental in vivo tests concerning implants fabricated from a nanostructured Ti6Al7Nb alloy, which may substitute bone tissue, were discussed in detail. The control group and test group were used in the study. The animal model was New Zealand rabbit. The implants were implanted into skull fornix and observed after 1, 2 and 3 months. The results of macroscopic and microscopic analysis proved better osseointegration of chemically modified implants.

The heat risk during hardening of dental glass-ionomer cements using a light-curing

An use of a polymerization lamp to irradiate chemically hardened glass-ionomer materials may improve their properties and accelerate the setting time. However, an excessive increase in the temperature of a material poses a potential risk for the dental pulp. Maximum temperatures reported during irradiation of selected glass-ionomers have been determined in this paper for samples of sizes similar to those used in clinical practice. Three glass-ionomer materials used for filling dental cavities have been examined: GC Fuji VIII, GC Fuji Triage Pink, and GC Fuji Triage White. The LED Elipar lamp was used in the light-curing process. The temperature measurement on the outer surface of the samples was conducted with the use of the Thermovision®550 thermal imaging camera. The examined materials significantly differed in the maximum temperatures they reached, as well as the time they required to reach these temperatures. A statistically significant positive correlation of maximum temperature with the sample weight was observed for the GC Fuji Triage Pink material.

Preliminary Evaluation of Thulium Doped Fiber Laser in Pig Model of Liver Surgery

Partial liver resection is a treatment of choice for liver tumors; the range of parenchyma excision varies from a small part of the tissue surrounding the neoplasm up to 70% of the organ. One of the major concerns during liver resection is blood loss. Thulium lasers which are characterized by the length of emission wave corresponding to a peak absorption of water create a new possibility of cutting tissues efficiently with minimal thermal damage and concurrently providing a good hemostasis control. The aim of our study was to evaluate an impact of liver transection with thulium doped fiber laser on an intraoperative bleeding and histopathological changes during postoperative period in swine model. Ten animals were subjected to open surgery partial liver resection and an incision of liver tissue with an all-fiber, diode-pumped, and continuous-wave Tm3+-doped fiber laser emitting 37.4 W of output power at ~1.94 μm wavelength. The macroscopic and histopathological evaluation was performed intraoperatively as well as 7 and 14 days after surgery. Macroscopically almost no bleeding was observed during surgery and no signs of bleeding were stated after 7 and 14 days. Histopathological analysis of the transection margin revealed a thermal damage area ranging in depth from 620.23 ± 23.82 μm on the day of surgery to 1817.70 ± 211.98 μm after 7 days. In the samples taken intraoperatively and after 7 days a superficial zone of carbonization was visibly separated from the deeper changes. After 14 days one 765.35 μm deep zone characterized by a granulation was present. In conclusion, thulium doped fiber laser is efficacious in cutting with a narrow zone of thermal injury and provides a good hemostasis during liver transection, thus being a potential tool for oncotic liver surgery.

Venous insufficiency: Differences in the content of trace elements. A preliminary report

BACKGROUND Venous insufficiency is still a serious clinical problem. The exact cause and molecular mechanisms of this disease are still unknown. In this study, we try to identify whether there is a difference in the level of trace elements between healthy and pathological veins. Our results show that insufficient veins have different levels of some trace elements: magnesium, calcium, manganese, and silicon compared to control samples. This study could lead to a better understanding of the molecular causes of venous insufficiency and may help to develop better methods of treatment. OBJECTIVES Nowadays, venous diseases are a very common clinical phenomenon. Venous insufficiency is thought to be one of the most common vein diseases. The exact mechanisms of its etiology are still unknown, although from a clinical point of view some risk factors include gender, age, changing hormone levels, heredity, and standing or sitting for long periods. An imbalance in trace elements could also play a crucial role in the development and/or progression of venous insufficiency. MATERIAL AND METHODS The trace element content in varicose vein walls and in normal vein walls was measured using an inductively coupled plasma-optical emission spectrometer (ICP-OES) after sample mineralization. Statistical analysis (the Mann-Whitney U test and the Friedman ANOVA) was performed to compare insufficient veins to controls (healthy veins). RESULTS This study found statistically significant higher magnesium (Mg) ion levels in varicose veins compared to controls (p = 0.0067) and differences close to statistical significance in calcium (Ca), manganese (Mn), and silicon (Si) ion levels. CONCLUSIONS The results obtained could indicate oxidative stress occurring in chronic venous insufficiency as well as free radical neutralization pathways due to superoxide dismutase (SOD) activity with Mg, Mn and copper (Cu) ion involvement. Our results are consistent with literature data and are preliminary in nature.