Publikacje 2017

Three-dimensional scaffolds are often used to support healing process for bone defects reconstruction.Unfortunately a common occurrence of post-implantation infections results in their high failure rate.Thus we propose new TiO2 scaffolds that combine mechanical support and controlled antibiotics release to assure bactericidal properties. Poly(L-lactide-co-glycolide) microparticles containing vancomycin were successfully immobilized on the scaffolds pore walls with the use of cross-linked sodium alginate. Prolonged drug release was achieved from such systems with initial burst release of 22% within 8 h,which falls within ‘‘decisive period” after surgical procedures of effective infection control.Antimicrobial properties of drug released from the systems against Staphylococcus spp. as well as cytocompatibility in contact with osteoblast-like cells (MG-63) were proven. Hence such scaffolds maybe promising for infection prevention and bone tissue defects treatment.

The  aim  of  this  work  was  to  examine  composite  membranes  obtained  by  means  of  phase  inversion  from  a  synthetic  stable  polymer  –  polyvinylidene  difluoride  (PVDF).  The  piezoelectric  polymer  was  modified with 0.5-1wt% addition of commercial carbon fillers: graphite oxide (GO, 1wt%), multiwalled carbon nanotubes  (CNT,  1wt%)  and  functionalized  nanotu-bes  (CNT-COOH,  0.5wt%).  The  membranes  were  obtained by solidification of nanocomposite solutions in  coagulation  bath  (CH3OH).  The  obtained  series  of  materials  differed  in  surface  porosity  (P),  electric  conductivity (σ) and surface free energy (SFE). It was proved that presence of carbon nanoadditive influen-ced microstructure of the membranes: the mean size of pores in the membrane rose in the following order: GO→CNT→CNT-COOH. The very same system de-picted the influence of the filler on the membrane stru-cture: the increase in membrane crystallinity (λ) and the β phase share (FT Raman). From all the examined nanocomposite  systems,  the  PVDF  modified  with  0.5wt% CNT-COOH displayed the most advantageous electric properties. These nanocomposite membrane (PVDF/CNT-COOH) could be used as a low-voltage electrodes in biomedical application. Yet, taking into account the other physicochemical, mechanical and structural  properties,  the  membranes  modified  with  1wt% CNT and 1wt% GO were also interesting.

Coating the material of choice with a layer of well-adhered carbon nanotubes is a subject of interest in many fields of materials science and industry. Electrophoretic deposition is one of the methods to handle this challenging task. In this process, careful designing of the deposition parameters is crucial in obtaining the product of strictly desired properties. This study was aimed to identify the influence of the diluent on the physicochemical ad electrochemical qualities of the final product. By analyzing the properties of the suspensions being used, we were able to hypothesize on the mechanisms of carbon nanotubes—liquid interactions and their outcome on the thickness, homogeneity, chemical and structural composition and electrical conductivity of the metal substrate covered with a layer of carbon nanotubes. We obtained a materials, composed of metal and a layer of CNTs, with conductivity that is superior to an unmodified metal. This types of materials may find numerous applications in fabrication of novel electronic devices, including the implantable electrodes for biomedicine—as reported in our previous studies, these types of coating are biocompatible.

The aim of this study was to evaluate the impact of multi-walled carbon nanotubes (MWCNTs) after chemical  surface  functionalization  on  the  interaction  with  a  titanium surface. Two kinds of MWCNTs differing in terms of concentration of functional groups were deposited on the Ti surface using the electrophoretic deposition method (EPD). The  study  has  shown  the  detailed  analysis  of  the  physicochemical  properties  of  this  form  of  carbon  nanomaterial  and  received  on  their  base  coatings  using  various  tech-niques, such as scanning electron microscopy (SEM), con-focal microscopy, X-ray photoelectron spectroscopy (XPS) and  Raman  spectroscopy.  The  adhesion  of  the  MWCNTs  coatings  to  the  Ti  surface  was  determined  using  the  shear  test   method,   according   to   standard   ASTM   F-1044-05.   These results indicated that one type of MWCNTs characterized  by  a  higher  concentration  of  functional  groups  has  better  adhesion  to  the  metal  surface  than  the  second  type.  Analysis  of  the  MWCNT–metal  interface  using  Raman  spectroscopy  and  SEM  and  STEM  indicates  the  presence  of phase built of MWCNT and  TiO2. This phase could be a type of nanocomposite that affects the improvement of the adhesion of MWCNT to the Ti surface.

The study was conducted to synthesize self-healing polyurethanes (PUs) in thepresence of multiwalled carbon nanotubes (CNTs). Measurements of the self-healing ability of PUs synthesized from N3300 isocyanate and polytetrahydro-furan with various contents of CNTs were taken. The mechanical and thermalproperties were studied to analyse healing efficiency in experimentally dam-aged composite samples. The addition of CNTs results in a slight decrease in theself-healing efficiency of nanocomposites as compared to pure PUs. PU samplescontaining 40% content of soft segments self-healed much better than thesamples with 50% content of soft segments. Functionalized carbon nanotubesCNT-OH due to presence of surface functional groups interact with PU chains,which results in an increase in the healing efficiency of mechanical strength andthermal conductivity of nanocomposites.

Titanium alloys varying in the silver content (3.5 at.%; 5 at.%; 10 at.% or 20 at.%) were produced by means of powder metallurgy. The alloys displayed different phase structure. In alloys with the silver content of 3.5 at.% and 5 at.% the solid solution α-Ti was identified. In alloys with the higher silver content, i.e. 10 and 20 at.%, both the solid solution and the equilibrium phase Ti2Ag were observed, whereas in alloys with the highest silver content of 20 at.% there were also the equilibrium phase TiAg and fine silver identified. The Ti-20%Ag alloy had 80% lower compressive stress and 30% lower hardness compared to the Ti-10%Ag alloy. The alloy with 10% silver showed the best mechanical properties as well as the best surface wettability.

This study presents a detailed evaluation of the impact of carbon fibrous materials on the physicochemical properties of polysulphone (PSU) membranes and their preliminary osteoblast-like cells response in vitro. Multi-walled carbon nanotubes (MWCNTs) and short carbon fibres (SCFs) were incorporated into PSU and membranes were produced by the phase inversion method. Then, the physicochemical properties of the membranes’ surface were investigated. Scanning electron microscopy (SEM) was used to evaluate microstructure and porosity. Surface properties such as roughness, wettability and surface energy were evaluated using atomic force microscopy (AFM),contact profilometry and a goniometer, respectively. The presence of carbon fibrous additives in the PSU matrix improved its hydrophilicity. Porosity and topography of the PSU membranes were also changed upon incorporation of carbon additives. The mechanical properties of the PSU membranes were improved after SCF addition. All physicochemical properties of the obtained composite membranes had significant impact on the osteoblast-like cells response. Preliminary viability tests indicated biocompatibility of all membranes.

Recent approaches in tissue regeneration focus on combining innovative achievements of stem cell biology and biomaterial sciences to develop novel therapeutic strategies for patients. Growing recent evidence indicates that mesenchymal stem cells harvested from human umbilical cord Wharton's jelly (hUC-MSCs) are a new valuable source of cells for autologous as well as allogeneic therapies in humans. hUC-MSCs are multipotent, highly pro- liferating cells with prominent immunoregulatory activity. In this study, we evaluated the impact of widely used FDA approved poly(α-esters) including polylactide (PLA) and polycaprolactone (PCL) on selected biological properties of hUC-MSCs in vitro. We found that both polymers can be used as non-toxic substrates for ex vivo propagation of hUC-MSCs as shown by no major impact on cell proliferation or viability. Moreover, PCL significantly enhanced the migratory capacity of hUC-MSCs. Importantly, genetic analysis indicated that both polymers promoted the angiogenic differentiation potential of hUC-MSCs with no additional chemical stimulation. These results indicate that PLA and PCL enhance selected biological properties of hUC-MSCs essential for their re- generative capacity including migratory and proangiogenic potential, which are required for effective vascular repair in vivo. Thus, PLA and PCL-based scaffolds combined with hUC-MSCs may be potentially employed as future novel grafts in tissue regeneration such as blood vessel reconstruction.

Silicon carbide nanoparticles (nSiC) have been used to modify coal tar pitch (CTP) as a carbon binder. The influence of ceramic nanoparticles on the structure and microstructure was studied. The structure of CTP-based carbon residue with various nSiC contents was analyzed by using SEM with EDAX, Raman spectroscopy, and X-ray diffraction. The effect of ceramic nanofiller on the crystallite sizes (, ) and the -axis spacing () in carbonized samples after heating from 1000 to 2800°C was analyzed. Ceramic nanofillers inhibit structural changes in carbonized samples heated to 1000°C. After heating CTP with nSiC above 2000°C, the carbon samples contained two carbon components differing in structural ordering. Ceramic nanoparticles increase carbon crystallite growth, while their impact on the -axis spacing is low.

The influence of nanohydroxyapatite on the glass transition region and its activation energy, as well as on the tribological and mechanical properties of polyoxymethylene nanocomposites, was investigated using DMA, TOPEM DSC, nanoindentation, and nondestructive ultrasonic methods. It was found that the glass transition for unmodified POM was in the lower temperature range than in POM/HAp nanocomposites. Moreover, and activation energy were larger for POM/HAp nanocomposites. Friction coefficient was higher for POM/HAp nanocomposites in comparison to both POM homopolymer and POM copolymer. Simultaneously, the indentation test results show that microhardness is also higher for POM/HAp nanocomposites than for POM. From ultrasonic investigations it was found that the highest values of both longitudinal and transverse propagation waves and Young’s and shear modulus for POM homopolymer (DH) and POM copolymer T2H and their nanocomposites can be attributed to their higher degree of crystallinity in comparison to UH copolymer. Moreover, for POM/HAp nanocomposites with 5% of HAp, ultrasonic longitudinal wave velocity was almost constant even after 1000000 mechanical loading cycles, evidencing an enhancement of mechanical properties by HAp nanoparticles.

Coal tar pitch (CTP) modified with silicon carbide nanoparticles (nSiC) was used as a carbon binder precursor for the manufacture of carbon materials. Carbon samples were prepared in the form of a composition consisting of synthetic coke, graphite and nSiC- modified CTP prior to heat treatment at temperatures from 800 °C to 2800 °C. The effect of ceramic nanofiller in CTP on oxidation resistance of carbon samples obtained at various temperatures was studied. Physical and mechanical properties of carbon samples obtained at 2000 °C and 2800 °C were analysed. nSiC presence in CTP was found to change the elevated temperature properties of carbon samples. The oxidation tests conducted at 600 °C in air showed a significant improvement of the resistance of carbon samples modified with small amount of nSiC and annealed at 2000 °C. Properties investigated included characteristics important for application of carbon materials for carbon electrode manufacturing, i.e., electrical and thermal conductivities as well as mechanical properties. Due to micro-structural changes of carbon samples in the presence of nSiC filler physical and mechanical properties improved after annealing the samples at high temperature in comparison to unmodified carbon samples.

The present work focuses on the state-of-the-art of biodegradable ceramic-polymer composites with particular emphasis on influence of various types of ceramic fillers on properties of the composites. First, the general needs to create composite materials for medical applications are briefly introduced. Second, various types of polymeric materials used as matrices of ceramic-containing composites and their properties are reviewed. Third, silica nanocomposites and their material as well as biological characteristics are presented. Fourth, different types of glass fillers including silicate, borate and phosphate glasses and their effect on a number of properties of the composites are described. Fifth, wollastonite as a composite modifier and its effect on composite characteristics are discussed. Sixth, composites containing calcium phosphate ceramics, namely hydroxyapatite, tricalcium phosphate and biphasic calcium phosphate are presented. Finally, general possibilities for control of properties of composite materials are highlighted.

The main objective of the presented research was to synthesise biodegradable aliphatic polycarbonates containing reactive carboxyl pendant groups and to examine the influence of the copolymer chain microstructure and composition on the process of their hydrolytic degradation and cytocompatibility. The work describes copolymerization of cyclic trimethylene carbonate derivative containing benzyl-ester pendant group (benzyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate) with trimethylene carbonate. The copolymerization was conducted with the use of zinc (II) and lanthanum (III) acetylacetonates as ring-opening polymerization coordination initiators. Detailed NMR analysis allowed to define the microstructure of the obtained copolymers, which depended on the composition and type of used initiator. The final tapered chain microstructure of the obtained copolymers was related to huge differences in comonomers reactivity and evidenced low level of transesterification of the main copolymer backbone. Chosen copolymers, with unprotected carbonyl groups, were subjected to in vitro degradation test and cytocompatibility studies. It was found that high concentration of carboxyl groups resulted in copolymers which formed hydrogels and were very prone to hydrolytic degradation; they were also cytotoxic toward osteoblast-like MG 63 cells. Copolymers with lower content of carboxyl groups were found less susceptible to degradation and cytocompatible with studied cells.

Hydrogels are popular materials for tissue regeneration. Incorporation of biologically active substances, e.g. enzymes, is straightforward. Hydrogel mineralization is desirable for bone regeneration. Here, hydrogels of Gellan Gum (GG), a biocompatible polysaccharide, were mineralized biomimetically with CaCO3 using a double enzymatic approach. The enzymes urease (U) and carbonic anhydrase (CA) were incorporated in GG hydrogels. Hydrogels were incubated in a mineralization solution containing U substrate (urea) and calcium ions. U converts urea to ammonia (which raises pH) and CO2. CA catalyses the reaction of CO2with water to form HCO3−, which undergoes deprotonation to form CO32−, which react with Ca2+ to form insoluble CaCO3.

Injectable composites for tissue regeneration can be developed by dispersion of inorganicmicroparticles and cells in a hydrogel phase. In this study, multifunctional carbonate microparticles containing different amounts of calcium, magnesium and zinc were mixed with solutions of gellan gum(GG), an anionic polysaccharide, to form injectable hydrogel–microparticle composites,containing Zn, Ca and Mg. Zn and Ca were incorporated into microparticle preparations to a greater extent than Mg. Microparticle groups were heterogeneous and contained microparticles of differing shape and elemental composition. Zn-rich microparticles were‘star shaped’and appeared to consist of small crystallites, while Zn-poor, Ca- and Mg-rich microparticles were irregular in shape and appeared to contain lager crystallites. Zn-free microparticle groups exhibited the best cytocompat-ibility and, unexpectedly, Zn-free composites showed the highest antibacterial activity towards methicilin-resistant Staphylococcus aureus. Composites containing Zn-free microparticles were cytocompatible and therefore appear most suitable for applications as an injectable biomaterial. This study proves the principle of creating bi- and tri-elemental microparticles to induce the gelation of GG to create injectable hydrogel–microparticle composites.

The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli (E. coli) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d(001) as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test.

The work presents the fatigue mechanical properties of a composite material made of polyetheretherketone (PEEK) polymer and carbon fibres (CF) designed for structural biomaterials. Composite samples with various types of carbon fibre reinforcements were studied. The mechanical durability of the composite samples in simulated body solution was analysed. The samples were loaded for a predetermined number of cycles for various applied-force levels, at a frequency of 50 Hz under a bending force, and at 1 Hz under compression force. The mechanical changes were analysed taking into consideration the anisotropic structure of the composite samples made of fibre roving 1D, 2D tissue and carbon fibres in the form of braided fibre sleeves (MD). The ultrasonic method was applied to determine the changes in velocities measured in the composites. The average variations of mechanical stability of the composite samples kept in simulated body fluid were not significant after fatigue testing up to 1 * 106 cycles.

Composite bioglass/chitosan and sol-gel glass/chitosan coatings were electrophoretically deposited (EPD) on a near-β Ti-13Nb-13Zr alloy. The influence of EPD parameters, such as chemical composition and suspension pH as well as potential difference and deposition time, on the uniformity of coatings has been studied. It was found that the pH value of the suspension and chemical composition have a significant impact on the electrokinetic properties of suspended chitosan molecules and glass particles, which in turn affect the deposition rate of EPD and the uniformity of as-deposited coatings. The thicknesses of the bioglass/chitosan and sol-gel glass/chitosan coatings were up to 2μm and 860nm, respectively. The microstructure of the coatings was characterized by scanning and transmission electron microscopy as well as X-ray diffractometry. The coating microstructure was composed of sol-gel glass particles or amorphous bioglass separate particles or agglomerates, homogeneously embedded in an amorphous chitosan matrix. The sol-gel particles consisted of hydroxyapatite (hp), CaSiO3 (tp) phases. The sol-gel glass/chitosan coating exhibited better adhesion to the titanium alloy substrate than the bioglass/chitosan coating. It was found that both types of coating improve the electrochemical corrosion resistance of the Ti-13Nb-13Zr alloy in Ringer's solution and are cytocompatible with osteoblast-like cells.

In this work, nanocomposite HA/chitosan coatings were electrophoretically deposited (EPD) on a near-β Ti-13Nb-13Zr alloy. The influence of the state of the HA particles introduced to the colloidal solution of chitosan (nc-HA-p as a nanopowder and nc-HA-s as nanoparticles suspended in ethanol), as well as the chemical composition of a multi-component HA-chitosan suspension and EPD parameters, on the homogeneity of coatings has been studied. It was established that the pH value and the chemical composition of the suspension have a substantial effect on the electrokinetic properties of suspended HA and chitosan particles. These are also influenced by the deposition kinetics of EPD and the uniformity of as-deposited coatings. The thickness of the nc-HA-p/chitosan and nc-HA-s/chitosan coatings was up to 750 nm and 1.5 μm, respectively. The nc-HA-s/chitosan coating microstructure consisted of HA nanoparticles, homogeneously embedded in an amorphous chitosan matrix. The nc-HA-p/chitosan coating microstructure was non-homogeneous, composed of HA agglomerates in a chitosan matrix. The presence of thin oxide layer was observed on the coatings/titanium alloy interface. The nc-HA-s/chitosan coating exhibited better adhesion to the titanium alloy substrate than the nc-HA-p/chitosan coating. It was found that the nc-HA-s/chitosan coating improves the electrochemical corrosion resistance of the Ti-13Nb-13Zr alloy in Ringer's solution, as well as its bioactivity and other biological properties.

The addition of an antibacterial agent to dental implants may provide the opportunity to decrease the percentage of implant failures due to peri-implantitis. For this purpose, in this study, the potential efficacy of nanosilver-doped titanium biomaterials was determined. Titanium disks were incorporated with silver nanoparticles over different time periods by Tollens reaction, which is considered to be an eco-friendly, cheap, and easy-to-perform method. The surface roughness, wettability, and silver release profile of each disc were measured. In addition, the antibacterial activity was also evaluated by using disk diffusion tests for bacteria frequently isolated from the peri-implant biofilm: Streptococcus mutans, Streptococcus mitis, Streptococcus oralis, Streptococcus sanguis, Porphyromonas gingivalis, Staphylococcus aureus, and Escherichia coli. Cytotoxicity was evaluated in vitro in a natural human osteoblasts cell culture. The addition of nanosilver significantly increased the surface roughness and decreased the wettability in a dose-dependent manner. These surfaces were significantly toxic to all the tested bacteria following a 48-hour exposure, regardless of silver doping duration. A concentration of 0.05 ppm was sufficient to inhibit Gram-positive and Gram-negative species, with the latter being significantly more susceptible to silver ions. However, after the exposure of human osteoblasts to 0.1 ppm of silver ions, a significant decrease in cell viability was observed by using ToxiLight™ BioAssay Kit after 72 hours. Data from the present study indicated that the incorporation of nanosilver may influence the surface properties that are important in the implant healing process. The presence of nanosilver on the titanium provides an antibacterial activity related to the bacteria involved in peri-implantitis. Finally, the potential toxicological considerations of nanosilver should further be investigated, as both the antibacterial and cytotoxic properties may be observed at similar concentration ranges.

During anodization, the properties of the oxide layer depend on the chemical composition of the titanium alloy and on the parameters applied during surface treatment. The properties of the anodized surfaces influence their further functionalization. In this paper, ceramic multilayer coatings were formed on the Ti-6Al-7Nb, Ti-13Nb-13Zr, and Ti-15Mo alloys. A silica layer with wollastonite particles was formed on all the previously anodized Ti alloy samples. Using scanning electron microscopy, Raman spectroscopy, and X-ray diffractometry, respectively, the surface morphology, chemical composition and phase composition of the hybrid ceramic layers were investigated. In addition, the adhesion and hardness of the coatings were determined. The contact angle of the coatings was between 90.0 ± 0.2° and 114.3 ± 5.9°, and the surface roughness was < 2 μm. The modified surfaces were immersed in solutions containing protein-like collagen type I or lactoferrin. The coated Ti-15Mo surface exhibited the highest influence on both types of protein concentration in phosphate-buffered saline solution. However, after 1 day of culture, the adsorbed lactoferrin on the entire surface enhanced the growth of osteoblast-like MG-63 cells. Significant differences in cell culture were observed after 7 days, where the number of cells was much higher on the modified surface with lactoferrin. Collagen type I did not significantly enhance the cell behaviour; moreover, a large number of dead cells were found on these samples.

This  paper  presents  the  characteristics  of  magnesium aluminium silicate–gentamicin complexes for drug delivery systems. The work describes the results of studies on  the  successful  introduction  of  gentamicin  (an  amino-glycoside  antibiotic)  into  the  interlayers  of  smectite  clay and examines the possible use of intercalated smectite as acarrier   for   sustained   drug   release.  Characterisation   of magnesium aluminium silicate–gentamicin complexes was carried  out  by  means  of  X-ray  diffraction,  Fourier  trans-form infrared spectroscopy, thermal analysis and scanning electron microscopy with EDX analysis. The possibility of using the gentamicin intercalated smectite as a carrier for sustained   release   of   the   drug   was   investigated   during in vitro study, in which the release rate of gentamicin from the  smectite  clay  matrix  was  monitored  based  on  absorption  at  330 nm  using  a  UV–Vis  spectrometer  and  the kinetic  of  drug  release  was  evaluated  based  on  the  zero-order, first-order, Higuchi and Korsmeyer–Peppas models.The  results  confirmed  the  efficiency  of  intercalation  and indicate  the  potential  for  introducing  gentamicin  into  the interlayer   space   of   montmorillonite.   Accordingly,   the obtained  material  may  thus  be  used  as  a  drug  carrier  in modulated drug delivery systems.

AIM:

To evaluate the utility of a novel nanocomposite biomaterial consisting of poly-L/D-lactide, and hydroxyapatite bioceramics, enriched with sodium alginate in articular cartilage defect treatment.

MATERIALS AND METHODS:

The biomaterial was prepared using the method of solvent casting and particle leaching. The study was conducted on 20 New Zealand White rabbits. Experimental osteochondral defects were created in the femoral trochlear grooves and filled with biomaterials. In control groups, the defects were left to spontaneously heal. The quality of newly-formed tissue was evaluated on the basis of macroscopic and histological assessment. Additionally the level of osteogenic and cartilage degradation markers were measured.

RESULTS:

The majority of the defects from the treatment group were covered with tissue similar in structure and colour to healthy cartilage, whereas in the control group, tissue was uneven, and not integrated into the surrounding cartilage.

CONCLUSION:

The results obtained validate the choice of biomaterial used in this study as well as the method of its application.

Objectives

This study aims at evaluating and comparing mechanical, chemical, and cytotoxicological parameters of a commercial brand name composite material against two ‘own brand label’ (OBL) composites.

Methods

Parameters included depth of cure, flexural strength, degree of conversion, polymerization shrinkage, filler particle morphology and elemental analyzes, Vickers hardness, surface roughness parameters after abrasion, monomer elution, and cytotoxicity.

Results

The conventional composite outperformed the OBLS in terms of depth of cure (p < 0.001), degree of cure at the first and last time intervals (p < 0.001), hardness (p < 0.001), and post-abrasion roughness (p < 0.05). The polymerization volumetric shrinkage ranged from 2.86% to 4.13%, with the highest shrinkage seen among the OBLs. Both Monomer elution from the OBLs was statistically significantly higher (p < 0.001). Statistically significantly higher cytotoxicity combined with altered morphology and loss of confluence was detected in the cells exposed to extracts from the OBLs.

Conclusions

The OBLs were in general outdone by the conventional composite.

Clinical significance

OBLs restorative materials have become pervasive in the dental market. Manufacturers often promise equal or better characteristics than existing brand-name composites, but at a lower price. Dentists are highly recommended to reconsider utilization of OBLs lacking sound scientific scrutiny, and our findings underscore this recommendation.

The aim of the study was to manufacture poly(lactic acid)- (PLA-) based nanofibrous nonwovens that were modified using two types of modifiers, namely, gelatin- (GEL-) based nanofibres and carbon nanotubes (CNT). Hybrid nonwovens consisting of PLA and GEL nanofibres (PLA/GEL), as well as CNT-modified PLA nanofibres with GEL nanofibres (PLA + CNT/GEL), in the form of mats, were manufactured using concurrent-electrospinning technique (co-ES). The ability of such hybrid structures as potential scaffolds for tissue engineering was studied. Both types of hybrid samples and one-component PLA and CNTs-modified PLA mats were investigated using scanning electron microscopy (SEM), water contact angle measurements, and biological and mechanical tests. The morphology, microstructure, and selected properties of the materials were analyzed. Biocompatibility and bioactivity in contact with normal human osteoblasts (NHOst) were studied. The coelectrospun PLA and GEL nanofibres retained their structures in hybrid samples. Both types of hybrid nonwovens were not cytotoxic and showed better osteoinductivity in comparison to scaffolds made from pure PLA. These samples also showed significantly reduced hydrophobicity compared to one-component PLA nonwovens. The CNT-contained PLA nanofibres improved mechanical properties of hybrid samples and such a 3D system appears to be interesting for potential application as a tissue engineering scaffold.

The aim of this study was to investigate the influence of the addition of smectite clay fillers to a polylactide matrix on the physical properties of the nanocomposites thus created, studied during the degradation process. A small amount of nanofiller (3–10 mass %) was used, and the clay was additionally modified with organic ammonium salt for better compatibility with the polymer matrix. Crystallisation, glass transition and melting temperature of the nanocomposites were investigated, and the resulting thermal, structural and mechanical properties were compared to those of a neat polylactide. The degradation process of the materials was examined during immersion in distilled water at 80 °C for 60 days using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Macroscopic changes were monitored and mechanical properties tested prior to degradation to evaluate the ability of the modified clay filler to reinforce the polymer and enhance elastic modulus, mechanical strength and Brinell hardness. The influence of the modified smectite filler on the thermal, mechanical and structural properties of the nanocomposites during degradation and its dependence on filler content were discussed and confirmed in the study. It was found that the addition of 3 mass% of the clay filler provides an increase of nearly 20 % in tensile strength, with improved stiffness. It was also found that the addition of organically modified clay to the polymer matrix significantly changes the hydrolytic degradation mechanisms of the polylactide, the crystallinity of the polymer and its degradation rate, depending on the amount of the filler.