Instytut Podstawowych Problemów Techniki

Streszczenie:

A novel metal matrix composites (MMC) with Mg matrix reinforced with natural filler in the form of Didymosphenia geminata frustules (algae with distinctive siliceous shells) are presented in this work. Pulse plasma sintering (PPS) was used to manufacture Mg-based composites with 1, 5 and 10 vol.% ceramic filler. As a reference, pure Mg was sintered. The results show that the addition of 1 vol.% Didymosphenia geminata frustules to the Mg matrix increases its corrosion resistance by supporting passivation reactions, and do not affect the morphology of L929 fibroblasts. Addition of 5 vol.% the filler does not cause cytotoxic effects, but it supports microgalvanic reactions leading to the greater corrosion rate. Higher content than 5 vol.% the filler causes significant microgalvanic corrosion, as well as increases cytotoxicity due to the greater micro-galvanic effect of the composites containing 10 and 15 vol.% diatoms. The results of contact angle measurements show the hydrophilic character of the investigated materials, with slightly increase in numerical values with addition of amount of ceramic reinforcement. The addition of Didymosphenia geminata frustules causes changes in a thermo-elastic properties such as mean apparent value of coefficient of thermal expansion (CTE) and thermal conductivity (λ). The addition of siliceous reinforcement resulted in a linear decrease of CTE and reduction in thermal conductivity over the entire temperature range. With the increasing addition of Didymosphenia geminata frustules, an increase in strength with a decrease in compressive strain is observed. In all composites an increase in microhardness was attained.
The results clearly indicate that filler in the form of Didymosphenia geminata frustules may significantly change the most important properties of pure Mg, indicating its wide potential in the application of Mg-based composites with a special focus on biomedical use.

Słowa kluczowe:

Metal-matrix composites (MMCs),Pulse plasma sintering (PPS),Ceramic filler,Microstructure,Properties

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Multifunctional composite biomaterials (3b-PU/CH_M) consisting of chitosan microspheres (CH-M) that provide drug release functionality and crosslinked polyester-urethane (3b-PU) matrix responsible for shape memory properties were designed. A series of 3b-PU/CH_M bio-composites with varying weight fraction of CH-M (2.5, 5, and 10 wt %) embedded into 3b-PU matrix were synthesized. The ATR-FTIR confirmed the presence of covalent bonds between 3b-PU matrix and CH-M as well as enhanced hydrogen bonds interaction within bio-composites matrix in comparison to neat 3b-PU. It was found that CH-M had not impaired the shape memory properties of 3b-PU matrix and even slightly improved the shape recovery (Rr %). The Rr value increased to 100% for 3b-PU/CH 2.5% M and 3b-PU/CH 5% M after the third thermo-mechanical cycle. Moreover, the transition temperature (Ttrans) of shape recovery tailored to 30 °C by the chemical composition of the 3b-PU network was not affected by CH-M. Effectiveness of the application of the composites as a controlled drug delivery system at various pH conditions was confirmed in an in vitro release study of ciprofloxacin hydrochloride (Cpx-HCl) used as a model drug. In vitro biocompatibility studies revealed that the materials do not alter the cells' ability to proliferate and differentiate.

Słowa kluczowe:

multifunctional composites, smart materials, shape memory behavior, multifunctional properties, drug release

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Fused Deposition Modelling (FDM) technique has been widely utilized in fabrication of 3D porous scaffolds for tissue engineering (TE) applications. Surprisingly, although there are many publications devoted to the architectural features of the 3D scaffolds fabricated by the FDM, none of them give us evident information about the impact of the diameter of the fibres on material properties. Therefore, the aim of this study was to investigate, for the first time, the effect of the diameter of 3D-printed PCL fibres on variations in their microstructure and resulting mechanical behaviour. The fibres made of poly(ε-caprolactone) (PCL) were extruded through commonly used types of nozzles (inner diameter ranging from 0.18 mm to 1.07 mm) by means of FDM technique. Static tensile test and atomic force microscopy working in force spectroscopy mode revealed strong decrease in the Young's modulus and yield strength with increasing fibre diameter in the investigated range. To explain this phenomenon, we conducted differential scanning calorimetry, wide-angle X-ray-scattering, Fourier-transform infrared spectroscopy, infrared and polarized light microscopy imaging. The obtained results clearly showed that the most prominent effect on the obtained microstructures and mechanical properties had different cooling and shear rates during fabrication process causing changes in supramolecular interactions of PCL. The observed fibre size-dependent formation of hydrogen bonds affected the crystalline structure and its stability. Summarising, this study clearly demonstrates that the diameter of 3D-printed fibres has a strong effect on obtained microstructure and mechanical properties, therefore should be taken into consideration during design of the 3D TE scaffolds.

Słowa kluczowe:

fused deposition modelling, polycaprolactone, mechanical properties, hydrogen bonds, microstructure

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Liquid-crystal-based biomaterials provide promising platforms for the development of dynamic and responsive interfaces for tissue engineering. Cholesteryl ester liquid crystals (CLCs) are particularly well suited for these applications, due to their roles in cellular homeostasis and their intrinsic ability to organize into supramolecular helicoidal structures on the mesoscale. Here, we developed a nonwoven CLC electrospun scaffold by dispersing three cholesteryl ester-based mesogens within polycaprolactone (PCL). We tuned the ratio of our mesogens so that the CLC would be in the mesophase at the cell culture incubator temperature of 37°C. In these scaffolds, the PCL polymer provided an elastic bulk matrix while the homogeneously dispersed CLC established a viscoelastic fluidlike interface. Atomic force microscopy revealed that the 50% (w/v) cholesteryl ester liquid crystal scaffold (CLC-S) exhibited a mesophase with topographic striations typical of liquid crystals. Additionally, the CLC-S favorable wettability and ultrasoft fiber mechanics enhanced cellular attachment and proliferation. Increasing the CLC concentration within the composites enhanced myoblast adhesion strength promoted myofibril formationin vitrowith mouse myoblast cell lines.

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Reproducing the advanced complexity of native tissue by means of the 3D multi-functional construct is a promising tissue engineering approach to osteochondral tissue regeneration. In this study, we present a porous 3D construct composed of three zones responsible for the regeneration of non-calcified cartilage, calcified cartilage and subchondral bone. These three zones of the hybrid were composed of modified biopolymers: (i) alginate (Alg) reinforced by short polylactide (PLA) fibres, (ii) alginate and gelatine methacrylate (GelMA) combined with ß-tricalcium phosphate particles (TCP), (iii) 3D printed polycaprolactone scaffold subsequently modified with the use of an innovative solvent treatment method based on acetone and ultrasound stimulation, respectively. Combining the advanced deposition systems based on: (i) 3D printing coupled with a spray crosslinking system, (ii) an innovative deposition system based on a coaxial-needle extruder, (iii) fused deposition modelling (FDM) connected with post-fabrication treatment, allows us to fabricate the triphasic construct that emulates the structure and properties of the native osteochondral tissue. The aim of the study was to investigate the mechanical properties of the fabricated hybrid and its individual zones. Our results demonstrate the load-bearing capabilities of TC, but nevertheless it should be implanted below the surface line of host cartilage to protect it from strong stresses, at the same time allowing native host tissues to grow into it.

Słowa kluczowe:

Triphasic scaffold, Osteochondral tissue engineering, Mechanical properties, Hydrogel with nanofillers, Modified PCL

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Fiber-based approaches hold great promise for tendon tissue engineering enabling the possibility of manufacturing aligned hydrogel filaments that can guide collagen fiber orientation, thereby providing a biomimetic micro-environment for cell attachment, orientation, migration, and proliferation. In this study, a 3D system composed of cell-laden, highly aligned hydrogel yarns is designed and obtained via wet spinning in order to reproduce the morphology and structure of tendon fascicles. A bioink composed of alginate and gelatin methacryloyl (GelMA) is optimized for spinning and loaded with human bone morrow mesenchymal stem cells (hBM-MSCs). The produced scaffolds are subjected to mechanical stretching to recapitulate the strains occurring in native tendon tissue. Stem cell differentiation is promoted by addition of bone morphogenetic protein 12 (BMP-12) in the culture medium. The aligned orientation of the fibers combined with mechanical stimulation results in highly preferential longitudinal cell orientation and demonstrates enhanced collagen type I and III expression. Additionally, the combination of biochemical and mechanical stimulations promotes the expression of specific tenogenic markers, signatures of efficient cell differentiation towards tendon. The obtained results suggest that the proposed 3D cell-laden aligned system can be used for engineering of scaffolds for tendon regeneration.

Słowa kluczowe:

hydrogel fibers, static mechanical stretching, stem cell alignment, tenogenic differentiation, wet spinning

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Tendon injuries are frequent and occur in the elderly, young, and athletic populations. The inadequate number of donors combined with many challenges associated with autografts, allografts, xenografts, and prosthetic devices have added to the value of engineering biological substitutes, which can be implanted to repair the damaged tendons. Electrospun scaffolds have the potential to mimic the native tissue structure along with desired mechanical properties and, thus, have attracted noticeable attention. In order to improve the biological responses of these fibrous structures, we designed and fabricated 3D multilayered composite scaffolds, where an electrospun nanofibrous substrate was coated with a thin layer of cell-laden hydrogel. The whole construct composition was optimized to achieve adequate mechanical and physical properties as well as cell viability and proliferation. Mesenchymal stem cells (MSCs) were differentiated by the addition of bone morphogenetic protein 12 (BMP-12). To mimic the natural function of tendons, the cell-laden scaffolds were mechanically stimulated using a custom-built bioreactor. The synergistic effect of mechanical and biochemical stimulation was observed in terms of enhanced cell viability, proliferation, alignment, and tenogenic differentiation. The results suggested that the proposed constructs can be used for engineering functional tendons.

Słowa kluczowe:

tendon tissue engineering, composite scaffolds, nanofibrous materials, mechanical stimulation, stem cell differentiation

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One promising strategy to reconstruct bone defects relies on 3D printed porous structures. In spite of several studies having been carried out to fabricate controlled, interconnected porous constructs, the control over surface features at, or below, the microscopic scale remains elusive for 3D polymeric scaffolds. In this study, we developed and refined a methodology which can be applied to homogeneously and reproducibly modify the surface of polymeric 3D printed scaffolds. We have demonstrated that the combination of a polymer solvent and the utilization of ultrasound was essential for achieving appropriate surface modification without damaging the structural integrity of the construct. The modification created on the scaffold profoundly affected the macroscopic and microscopic properties of the scaffold with an increased roughness, greater surface area, and reduced hydrophobicity. Furthermore, to assess the performance of such materials in bone tissue engineering, human mesenchymal stem cells (hMSC) were cultured in vitro on the scaffolds for up to 7 days. Our results demonstrate a stronger commitment toward early osteogenic differentiation of hMSC. Finally, we demonstrated that the increased in the specific surface area of the scaffold did not necessarily correlate with improved adsorption of protein and that other factors, such as surface chemistry and hydrophilicity, may also play a major role.

Słowa kluczowe:

surface modification, solvent treatment, polycaprolactone, BMP-2 adsorption

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One promising strategy to reconstruct osteochondral defects relies on 3D bioprinted three-zonal structures comprised of hyaline cartilage, calcified cartilage, and subchondral bone. So far, several studies have pursued the regeneration of either hyaline cartilage or bone in vitro while—despite its key role in the osteochondral region—only few of them have targeted the calcified layer. In this work, we present a 3D biomimetic hydrogel scaffold containing β-tricalcium phosphate (TCP) for engineering calcified cartilage through a co-axial needle system implemented in extrusion-based bioprinting process. After a thorough bioink optimization, we showed that 0.5% w/v TCP is the optimal concentration forming stable scaffolds with high shape fidelity and endowed with biological properties relevant for the development of calcified cartilage. In particular, we investigate the effect induced by ceramic nano-particles over the differentiation capacity of bioprinted bone marrow-derived human mesenchymal stem cells in hydrogel scaffolds cultured up to 21 d in chondrogenic media. To confirm the potential of the presented approach to generate a functional in vitro model of calcified cartilage tissue, we evaluated quantitatively gene expression of relevant chondrogenic (COL1, COL2, COL10A1, ACAN) and osteogenic (ALPL, BGLAP) gene markers by means of RT-qPCR and qualitatively by means of fluorescence immunocytochemistry.

Słowa kluczowe:

alginate, gelatin methacrylate, ß-tricalcium phosphate TCP, bioprinting, coaxial needle, calcified cartilage

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Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients.

Słowa kluczowe:

graded scaffolds, rapid prototyping, bioinspired, microfluidic, gradient characterization, cartilage, bone

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Chronic, non-healing wounds place a significant burden on patients and healthcare systems, resulting in impaired mobility, limb amputation, or even death. Chronic wounds result from a disruption in the highly orchestrated cascade of events involved in wound closure. Significant advances in our understanding of the pathophysiology of chronic wounds have resulted in the development of drugs designed to target different aspects of the impaired processes. However, the hostility of the wound environment rich in degradative enzymes and its elevated pH, combined with differences in the time scales of different physiological processes involved in tissue regeneration require the use of effective drug delivery systems. In this review, we will first discuss the pathophysiology of chronic wounds and then the materials used for engineering drug delivery systems. Different passive and active drug delivery systems used in wound care will be reviewed. In addition, the architecture of the delivery platform and its ability to modulate drug delivery are discussed. Emerging technologies and the opportunities for engineering more effective wound care devices are also highlighted.

Słowa kluczowe:

Wound healing, Drug delivery, Transdermal delivery, Microtechnologies, Nanotechnologies

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Injection of cell‐laden scaffolds in the form of mesoscopic particles directly to the site of treatment is one of the most promising approaches to tissue regeneration. Here, a novel and highly efficient method is presented for preparation of porous microbeads of tailorable dimensions (in the range ≈300–1500 mm) and with a uniform and fully interconnected internal porous texture. The method starts with generation of a monodisperse oil‐in‐water emulsion inside a flow‐focusing microfluidic device. This emulsion is later broken‐up, with the use of electric field, into mesoscopic double droplets, that in turn serve as a template for the porous microbeads. By tuning the amplitude and frequency of the electric pulses, the template droplets and the resulting porous bead scaffolds are precisely produced. Furthermore, a model of pulsed electrodripping is proposed that predicts the size of the template droplets as a function of the applied voltage. To prove the potential of the porous microbeads as cell carries, they are tested with human mesenchymal stem cells and hepatic cells, with their viability and degree of microbead colonization being monitored. Finally, the presented porous microbeads are benchmarked against conventional microparticles with nonhomogenous internal texture, revealing their superior performance.

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The degradation in vivo and its effect on the supermolecular structure of poly(caprolactone) was examined. Poly(caprolactone) (PCL) samples were prepared in the form of porous scaffolds implanted into rat calvarial defects. The degradation was investigated by means of gel permeation chromatography, wide angle X-ray scattering (WAXS), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The study showed that the observed decrease of PCL crystallinity during degradation is accompanied by reduction of crystal size and/or perfection. The observed phenomenon could be explained by the presence of the high content of the low mobile fraction of investigated polymer, consisting not only almost 50% of crystal fraction but also most probably relatively high fraction of s.c. rigid amorphous fraction (RAF). Considering the type of structure characterized by the dominance of low mobile fraction, it is expected that the degradation will mainly concern these fractions, which in turn will lead to a decrease in the degree of crystallinity as well as crystal size and/or perfection.

Słowa kluczowe:

PCL degradation, In-vivo conditions, Crystallinity, Rigid amorphous fraction

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Physical and chemical factors resulting from the sterilization methods may affect the structure and properties of the materials which undergo this procedure. Poly(l-lactide-co-glicolide) (PLGA) is commonly used for medical applications, but, due to its inadequate mechanical properties, it is not recommended for load-bearing applications. One of the methods for improving PLGA mechanical properties is addition of hydroxyapatite nanoparticles (nHAp). The aim of this study was to evaluate the effect of nanoparticles addition on PLGA structure and properties after gamma radiation. According to our results, reduction of the molecular mass caused by gamma radiation was lower for PLGA with nHAp addition. Differential scanning calorimetry (DSC) analysis indicates an increase of crystallinity caused both by nHAp and gamma radiation. The first phenomenon can be explained by heteronucleation, while the second one is most probably related to higher molecular mobility of degrading polymer. Moreover, addition of nanoparticles increases thermal stability and affects the Young's modulus changes after gamma radiation.

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Electrospun nanofibrous scaffolds are willingly used in tissue engineering applications due to their tunable mechanical, chemical and physical properties. Additionally, their complex openworked architecture is similar to the native extracellular matrix of living tissue. After implantation such scaffolds should provide sufficient mechanical support for cells. Moreover, it is of crucial importance to ensure sterility and hydrophilicity of the scaffold. For this purpose, a low temperature surface plasma treatment can be applied. In this paper, we report physico-mechanical evaluation of stiffness and adhesive properties of electrospun mats after their exposition to low temperature plasma. Complex morphological and mechanical studies performed with an atomic force microscope were followed by scanning electron microscope imaging and a wettability assessment. The results suggest that plasma treatment can be a useful method for the modification of the surface of polymeric scaffolds in a desirable manner. Plasma treatment improves wettability of the polymeric mats without changing their morphology.

Słowa kluczowe:

Atomic force microscopy, Surface modification, Electrospun fibers, RF plasma treatment, Tissue engineering, Nanomaterial

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In this paper, the effect of the presence of L929 fibroblast cells and a cyclic load application on the kinetics of the degradation of amorphous PLGA films was examined. Complex micro and nano morphological, mechanical and physico-chemical studies were performed to assess the degradation of the tested material. For this purpose, molecular weight, glass transition temperature, specimen morphology (SEM, μCT) and topography (AFM) as well as the stiffness of the material were measured. The study showed that the presence of living cells along with a mechanical load accelerates the PLGA degradation in comparison to the degradation occurring in acellular media: PBS and DMEM. The drop in molecular weight observed was accompanied by a distinct increase in the tensile modulus and surface roughness, especially in the case of the film degradation in the presence of cells. The suspected cause of the rise in stiffness during the degradation of PLGA films is a reduction in the molecular mobility of the distinctive superficial layer resulting from severe structural changes caused by the surface degradation. In conclusion, all the micro and nanoscale properties of amorphous PLGA considered in the study are sensitive to the presence of L929 cells, as well as to a cyclic load applied during the degradation process.

Słowa kluczowe:

L929, aliphatic polyester, stiffness rise

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Tissue engineering holds great potential in the production of functional substitutes to restore, maintain or improve the functionality in defective or lost tissues. So far, a great variety of techniques and approaches for fabrication of scaffolds have been developed and evaluated, allowing researchers to tailor precisely the morphological, chemical and mechanical features of the final constructs. Electrospinning of biocompatible and biodegradable polymers is a popular method for producing homogeneous nanofibrous structures, which might reproduce the nanosized organization of the tendons. Moreover, composite scaffolds obtained by incorporating nanoparticles within electrospun fibers have been lately explored in order to enhance the properties and the functionalities of the pristine polymeric constructs. The present study is focused on the design and fabrication of biocompatible electrospun nanocomposite fibrous scaffolds for tendon regeneration. A mixture of poly(amide 6) and poly(caprolactone) is electrospun to generate constructs with mechanical properties comparable to that of native tendons. To improve the biological activity of the constructs and modify their topography, wettability, stiffness and degradation rate, we incorporated silica particles into the electrospun substrates. The use of nanosize silica particles enables us to form bead-on-fiber topography, allowing the better exposure of ceramic particles to better profit their beneficial characteristics. In vitro biocompatibility studies using L929 fibroblasts demonstrated that the presence of 20 wt% of silica nanoparticles in the engineered scaffolds enhanced cell spreading and proliferation as well as extracellular matrix deposition. The results reveal that the electrospun nanocomposite scaffold represents an interesting candidate for tendon tissue engineering.

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Periodontitis is a prevalent chronic, destructive inflammatory disease affecting tooth‐supporting tissues in humans. Guided tissue regeneration strategies are widely utilized for periodontal tissue regeneration generally by using a periodontal membrane. The main role of these membranes is to establish a mechanical barrier that prevents the apical migration of the gingival epithelium and hence allowing the growth of periodontal ligament and bone tissue to selectively repopulate the root surface. Currently available membranes have limited bioactivity and regeneration potential. To address such challenges, an osteoconductive, antibacterial, and flexible poly(caprolactone) (PCL) composite membrane containing zinc oxide (ZnO) nanoparticles is developed. The membranes are fabricated through electrospinning of PCL and ZnO particles. The physical properties, mechanical characteristics, and in vitro degradation of the engineered membrane are studied in detail. Also, the osteoconductivity and antibacterial properties of the developed membrane are analyzed in vitro. Moreover, the functionality of the membrane is evaluated with a rat periodontal defect model. The results confirmed that the engineered membrane exerts both osteoconductive and antibacterial properties, demonstrating its great potential for periodontal tissue engineering.

Słowa kluczowe:

electrospinning, guided tissue regeneration, osteoconductive, periodontal regeneration, zinc oxide

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In this research, the effect of the presence of living cells (SaOS-2) on in vitro degradation of Mg-2.0Zn-0.98Mn (ZM21) magnesium alloy was examined by two methods simple immersion/cell culture tests and electrochemical measurements (electrochemical impedance spectroscopy and potentiodynamic polarization) under cell culture conditions. In immersion/cell culture tests, when SaOS-2 cells were cultured on ZM21 samples, pH of cell culture medium decreased, therefore weight loss and Mg2+ ion release from the samples increased. Electrochemical measurements revealed the presence of living cells increased corrosion rate (Icorr) and decreased polarization resistance (Rp) after 48 h of incubation. This acceleration of ZM21 corrosion can mainly be attributed to the decrease of medium pH due to cellular metabolic activities.

Słowa kluczowe:

biodegradable metals, biomaterials, electrochemical impedance spectroscopy, immersion, cell culture condition

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Tissue engineering (TE) aims to mimic the complex environment where organogenesis takes place using advanced materials to recapitulate the tissue niche. Cells, three-dimensional scaffolds and signaling factors are the three main and essential components of TE. Over the years, materials and processes have become more and more sophisticated, allowing researchers to precisely tailor the final chemical, mechanical, structural and biological features of the designed scaffolds. In this review, we will pose the attention on two specific classes of naturally derived polymers: fibrous proteins and glycosaminoglycans (GAGs). These materials hold great promise for advances in the field of regenerative medicine as i) they generally undergo a fast remodeling in vivo favoring neovascularization and functional cells organization and ii) they elicit a negligible immune reaction preventing severe inflammatory response, both representing critical requirements for a successful integration of engineered scaffolds with the host tissue. We will discuss the recent achievements attained in the field of regenerative medicine by using proteins and GAGs, their merits and disadvantages and the ongoing challenges to move the current concepts to practical clinical application.

Słowa kluczowe:

Natural polymers, Hydrogel scaffolds, Glycosaminoglycans (GAGs), Fibrous proteins, Regenerative medicine

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In this study, we present an innovative strategy to reinforce 3D-printed hydrogel constructs for cartilage tissue engineering by formulating composite bioinks containing alginate and short sub-micron polylactide (PLA) fibers. We demonstrate that Young's modulus obtained for pristine alginate constructs (6.9 ± 1.7 kPa) can be increased threefold (up to 25.1 ± 3.8 kPa) with the addition of PLA short fibers. Furthermore, to assess the performance of such materials in cartilage tissue engineering, we loaded the bioinks with human chondrocytes and cultured in vitro the bioprinted constructs for up to 14 days. Live/dead assays at day 0, 3, 7 and 14 of in vitro culture showed that human chondrocytes were retained and highly viable (∼80%) within the 3D deposited hydrogel filaments, thus confirming that the fabricated composites materials represent a valid solution for tissue engineering applications. Finally, we show that the embedded chondrocytes during all the in vitro culture maintain a round morphology, a key parameter for a proper deposition of neocartilage extracellular matrix.

Słowa kluczowe:

alginate, PLA, short fibers, hydrogel reinforcement, chondrocytes

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Four kinds of biodegradable polymers were employed to prepare bioresorbable coatings on Mg-2.0Zn-0.98Mn (ZM21) alloy to understand the relationship between polymer characteristics, protective effects on substrate corrosion, cytocompatibility and cell functionality. Poly-l-lactide (PLLA), poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(lactic-co-glycolic) acid (PLGA) was spin-coated on ZM21, obtaining a smooth, non-porous coating less than 0.5 μm in thickness. Polymer coating characterization, a degradation study, and biocompatibility evaluations were performed. After 4 w of immersion into cell culture medium, degradation of PLGA and PLLA coatings were confirmed by ATR-FTIR observation. The coatings of PLLA, PHB and PHBV, which have lower water permeability and slower degradation than PLGA, provide better suppression of initial ZM21 degradation and faster promotion of human osteosarcoma cell growth and differentiation.

Słowa kluczowe:

Biodegradable metal, Magnesium alloy, Biodegradable polymer, SaOS-2 differentiation, Calcification

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In vitro degradation behavior of squeeze cast (CAST) and equal channel angular pressed (ECAP) ZM21 magnesium alloy (2.0 wt% Zn-0.98 wt% Mn) was studied using immersion tests up to 4 w in three different biological environments. Hanks' Balanced Salt Solution (Hanks), Earle's Balanced Salt Solution (Earle) and Eagle minimum essential medium supplemented with 10% (v/v) fetal bovine serum (E-MEM + 10% FBS) were used to investigate the effect of carbonate buffer system, organic compounds and material processing on the degradation behavior of the ZM21 alloy samples. Corrosion rate of the samples was evaluated by their Mg2 + ion release, weight loss and volume loss. In the first 24 h, the corrosion rate sequence of the CAST samples was as following: Hanks > E-MEM + 10% FBS > Earle. However, in longer immersion periods, the corrosion rate sequence was Earle > E-MEM + 10% FBS ≥ Hanks. Strong buffering effect provided by carbonate buffer system helped to maintain the pH avoiding drastic increase of the corrosion rate of ZM21 in the initial stage of immersion. Organic compounds also contributed to maintain the pH of the fluid. Moreover, they adsorbed on the sample surface and formed an additional barrier on the insoluble salt layer, which was effective to retard the corrosion of CAST samples. In case of ECAP, however, this effect was overcome by the occurrence of strong localized corrosion due to the lower pH of the medium. Corrosion of ECAP samples was much greater than that of CAST, especially in Hanks, due to higher sensitivity of ECAP to localized corrosion and the presence of Cl−.

The present work demonstrates the importance of using an appropriate solution for a reliable estimation of the degradation rate of Mg-base degradable implants in biological environments, and concludes that the most appropriate solution for this purpose is E-MEM + 10% FBS, which has the closest chemical composition to human blood plasma.

Słowa kluczowe:

ZM21 magnesium alloy, ECAP, Simulated body fluids, In vitro degradationBicomponent nanofibers, Biodegradation, Biopolymer

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The aim of the present study was preparation, optimization, and systematic characterization of electrospun bionanocomposite fibers based on polyvinyl alcohol (PVA) as matrix and nanohydroxy apatite (nHAp) and cellulose nanofibers (CNF) as nanoreinforcements. The presence of nHAp and nHAp-CNF affected the morphology of electrospun mats and reduced fiber diameter, particularly at a higher content of nanofillers. The obtained results of FTIR, DSC, and WAXS proved the crystallinity reduction of electrospun nancomposites. Both nHAp and nHAp-CNF addition led to a significant increase of Young modulus with the highest stiffness for nanocomposite fibers at 10 wt% of nHAp and 3 wt% of CNF.

Słowa kluczowe:

Bionanocomposite, cellulose nanofibers, electrospinning, nanohydroxy apatite

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The aim of this study was to change the surface of sodium alginate hydrogel by electrostatic binding of poly-l-lysine (PLL) in order to provide more advantageous conditions for connective tissue development. Its impact on L929 mouse fibroblast adhesion, morphology and viability was investigated. Analysis of the material microstructure has shown that performed modification increased surface roughness. It also altered the swelling properties of alginate hydrogel, resulting in less rapid water absorption. Mouse fibroblasts seeded on regular alginate and alginate modified with PLL exhibited different behaviour. The presence of PLL turned out to promote cell adhesion and F-actin spreading, resulting in significantly increased number of viable cells 96 h after seeding.

Słowa kluczowe:

Alginate, Poly-l-lysine, Electrolyte membranes, Cell adhesion

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The progress in the treatment of chronic diseases of civilization that occurred in recent years, led to a significant prolongation of median survival time of the developed countries societies. Organ transplantation has revolutionized medicine as it became possible to replace an irreversibly diseased organ. However, at the moment we can observe a significant shortage of organs for transplantation, which forces doctors to accept those coming from more and more expanding criteria donors. No doubt, the number of donors, at best, will certainly not grow. Tissue engineering and regenerative medicine methods are extremely promising, in particular bioprinting of tissues and organs, which begun to develop at the beginning of the XXI century. Article highlights possible future direction of organ transplantation.

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The integration and long-term functional retention of tissue implants are both strongly linked to the implant material characteristics. As a first approach, the cytocompatibility and bioactivity of such materials are evaluated using in vitro-based cell culture models. Typically, in vitro bioactivity is assessed by seeding single cells onto the test material to evaluate certain parameters such as cell adhesion, survival, proliferation, and functional differentiation. Probably, due to the reduction from three dimensional (3D) toward the two dimensional (2D) situation the data obtained from 2D culture models falls short of predicting the in vivo behavior of the biomaterial in question. In this study, a three dimensional (3D) in vitro cell culture model was applied to evaluate the bioactivity of well characterized fiber-based scaffolds using scaffold colonization as a bioactivity indicator. Cell behavior in this culture model was evaluated against a classical comparable, 2D cell culture system using polyethylene terephthalat and polyamide 6.6 fabrics. By using the 3D culture model, however, differences in cell population performance as a function of fiber diameter and mesh angle were evident. The use of 3D cell culture model clearly outperformed typical cell culture setup as means to evaluate cell population–scaffold interaction.

Słowa kluczowe:

scaffold, textile, polyamide 6.6, polyethylene terephthalat, osteoblast, fibroblast, reaggregate, 3D

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The aim of this paper is to describe the effects of wear particles, generated during articulation of the bearing surfaces of the total joint prosthesis on bone-implant interface. Submicron particles migrate into effective joint space and stimulate cells present in the fibrous tissue to release molecular signal. Cytokines activate the osteoclasts and in consequence bone loss may result. It weakens the bone-implant fixation and may cause aseptic loosening of the prosthesis.

Słowa kluczowe:

wear debris, bone–implant interface, total joint replacemtnt

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Application of a biodegradable polymer coating is one of the methods to improve the initial corrosion resistance and cytocompatibility of magnesium (Mg) alloys. However, bulging of the coating film during long term immersion has been reported. Therefore, improvement of interface strength between the coating and the substrate surface is a key for the success of this method. Combination of surface modification [silanization with 3- (glycidyloxypropyl) triethoxysilane (GPTES)] and biodegradable polymer coating [poly-L-lactide (PLLA)] were applied to a Mg- 2.0Zn-0.98Mn (ZM21) cast alloy. Results of a cell proliferation assay show that PLLA and GPTES+PLLA coating successfully improved cell growth during 7 days of incubation and suppressed Mg2+ release after 4 days of incubation. The silanization process had no impact on suppression of corrosion. Calcification was observed on all samples after 1 week of incubation with calcification medium, but the calcified area was much larger on the GPTES+PLLA coated sample than on the uncoated sample.

Słowa kluczowe:

biodegradable metal, ZM21, cytocompatibility, silane-coupling, PLLA

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The use of the ultrasonically destructible microcapsules as local drug delivery systems continues to grow. Microbubble destruction requires correct ultrasonic frequency equal to its resonance. This frequency depends on the bubble size and polymer shell stiffness. Measurements of the ultrasonic signal, backscattered from microspheres gives practical information of the bubble resonance and nonlinearity.
In experiment, the backscattered power spectrum of measured sample was recorded by an ultrasonic scanner. Radio frequency (RF) data was recorded at 2.0 – 6.6 MHz. The mean particle diameter in the measured sample was 21 μm. The resonance frequency, measured under the microscope, was 0.60 MHz for 43 μm diameter microsphere. The sample volume was 10cm³ and the mean quantity of scatterers was 6•103/cm³.
The simulated power spectrum of the ultrasonic backscattered signal was calculated from the resonance scattering theory for the gas bubbles surrounded by elastic shell.
In conclusion, the measured spectra matched those calculated from the theory. The use of the ultrasonic scanner with RF data output and the high sensitivity, wide bandwidth ultrasonic transducer allows to measure the backscattered signal from the very small quantity of resonance scatterers with satisfactory results at 40 dB signal to noise ratio.

Słowa kluczowe:

ultrasound, microcapsules, controlled drug delivery, backscattering

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The paper presents the results of experimental investigation on polymer foam with shape memory properties. The research is focused on characterization of the microstructure of the foam and understanding the mechanisms of deformation under static and dynamic loading. Up till now, selected experimental techniques have been applied. Dynamic Mechanical Analysis (DMA) allows determining the extent of the value of the glass transition temperature under different load conditions, which also reveals the transformation temperature range for the SMP foam. Scanning electron microscopy (SEM) shows the foam microstructure in various scales, while X-ray tomography gave 3D microstructure results presenting in addition mechanism of the cells deformation and changes in their geometry under 30 % and 50% strain. BOSE system enables obtaining the results on dynamic loading.

Słowa kluczowe:

Shape memory polymer foam, Dynamic mechanical analysis, Glass transition temperature, X-ray tomography

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