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Abstract:
In recent years, one of the main goals of cartilage tissue engineering has been to find appropriate scaffolds for hyaline cartilage regeneration, which could serve as a matrix for chondrocytes or stem cell cultures. The study presents three types of scaffolds obtained from a blend of polyethersulfone (PES) and polyurethane (PUR) by a combination of wet-phase inversion and salt-leaching methods. The nonwovens made of gelatin and sodium chloride (NaCl) were used as precursors of macropores. Thus, obtained membranes were characterized by a suitable structure. The top layers were perforated, with pores over 20 µm, which allows cells to enter the membrane. The use of a nonwoven made it possible to develop a three-dimensional network of interconnected macropores that is required for cell activity and mobility. Examination of wettability (contact angle, swelling ratio) showed a hydrophilic nature of scaffolds. The mechanical test showed that the scaffolds were suitable for knee joint applications (stress above 10 MPa). Next, the scaffolds underwent a degradation study in simulated body fluid (SBF). Weight loss after four weeks and changes in structure were assessed using scanning electron microscopy (SEM) and MeMoExplorer Software, a program that estimates the size of pores. The porosity measurements after degradation confirmed an increase in pore size, as expected. Hydrolysis was confirmed by Fourier-transform infrared spectroscopy (FT-IR) analysis, where the disappearance of ester bonds at about 1730 cm −1 wavelength is noticeable after degradation. The obtained results showed that the scaffolds meet the requirements for cartilage tissue engineering membranes and should undergo further testing on an animal model.

Keywords:
articular cartilage, cartilage tissue engineering, hydrolysis process, materials for scaffolds, partly degradable scaffolds, polyethersulfone–polyurethane scaffolds, polyurethane degradation, regenerative medicine, scaffold requirements, tissue engineering

Abstract:
An innovative approach to treating bone defects is using synthetic bone substitutes made of biomaterials. The proposed method to obtain polylactide scaffolds using the phase inversion technique with a freeze extraction variant enables the production of substitutes with morphology similar to cancellous bone (pore size 100–400 µm, open porosity 94%). The high absorbability of the implants will enable their use as platelet-rich plasma (PRP) carriers in future medical devices. Surface modification by dipping enabled the deposition of the hydrophilic chitosan (CS) layer, maintaining good bone tissue properties and high absorbability (850% dry weight). Introducing CS increases surface roughness and causes local changes in surface free energy, promoting bone cell adhesion. Through this research, we have developed a new and original method of low-temperature modification of PLA substitutes with chitosan. This method uses non-toxic reagents that do not cause changes in the structure of the PLA matrix. The obtained bone substitutes are characterised by exceptionally high hydrophilicity and morphology similar to spongy bone. In vitro studies were performed to analyse the effect of morphology and chitosan on cellular viability. Substitutes with properties similar to those of cancellous bone and which promote bone cell growth were obtained.

Keywords:
chitosan, polylactide, bone substitute, tissue regeneration

Abstract:
The cartilage tissue is neither supplied with blood nor innervated, so it cannot heal by itself. Thus, its reconstruction is highly challenging and requires external support. Cartilage diseases are becoming more common due to the aging population and obesity. Among young people, it is usually a post-traumatic complication. Slight cartilage damage leads to the spontaneous formation of fibrous tissue, not resistant to abrasion and stress, resulting in cartilage degradation and the progression of the disease. For these reasons, cartilage regeneration requires further research, including use of new type of biomaterials for scaffolds. This paper shows cartilage characteristics within its most frequent problems and treatment strategies, including a promising method that combines scaffolds and human cells. Structure and material requirements, manufacturing methods, and commercially available scaffolds were described. Also, the comparison of poly(L-lactide) (PLLA) and polyethersulfone (PES) 3D membranes obtained by a phase inversion method using nonwovens as a pore-forming additives were reported. The scaffolds' structure and the growth ability of human chondrocytes were compared. Scaffolds' structure, cells morphology, and protein presence in the membranes were examined with a scanning electron microscope. The metabolic activity of cells was tested with the MTT assay. The structure of the scaffolds and the growth capacity of human chondrocytes were compared. Obtained results showed higher cell activity and protein content for PES scaffolds than for PLLA. The PES membrane had better mechanical properties (e.g. ripping), greater chondrocytes proliferation, and thus a better secretion of proteins which build up the cartilage structure.

Keywords:
3D-scaffolds, membrane structure, polyethersulfone, poly(L-lactide), chondrocyte culture, cartilage regeneration

Abstract:
The study presents two types of three-dimensional membranes made of the biodegradable copolymer. They were obtained by the wet-phase inversion method using different solvent and pore precursors. In one case, a nonwoven made of gelatin and polyvinylpyrrolidone (PVP) as precursors of macropores and small pores, respectively, were used. In the second case, PVP nonwovens and Pluronic were used properly for macro- and micro-pores. As the material, a biodegradable poly(L-lactide-co-ε-caprolactone) is composed of 30% ε-caprolactone and 70% poly(L-lactic acid) was used. Depending on the pore precursors, different membrane structures were obtained. The morphology of pores was studied using the MeMoExplorer™, an advanced software designed for computer analysis of the scanning electron microscopy images. The scaffolds were degraded in phosphate-buffered saline and Hank’s balanced salt solutions at 37°C. Moreover, the porosity of the membranes before and after hydrolysis was calculated.

Keywords:
3D scaffolds, poly(L-lactide-co-ε-caprolactone), porosity of membrane, phase inversion method, degradation of scaffolds

Abstract:
An innovative modification of the wet inversion phase method, consisting in the use of a polymer nano‐nonwoven as a nonclassic pore precursor. Mechanical properties of the obtained scaffolds were determined, their hydrophilic properties (serum absorbability) were tested, and the content of residues of materials used in the scaffold preparation was determined. Nontoxicity of the developed scaffolds toward T lymphocyte cells was proved. Cultures of primary chondrocytes were obtained successfully. It was proved that an addition of a polymer nano‐nonwoven changes the properties of the scaffolds favorably in respect of their subsequent application in tissue engineering.

Keywords:
cartilage regeneration, chondrocytes, nano-nonwoven, polyvinylpyrrolidone, T lymphocytes

Abstract:
Results of the preparation of biodegradable porous scaffolds using an original modification of a wet phase inversion method were presented. Influence of gelatin non‐woven as a non‐classic pore precursor and polyvinylpyrrolidone, Pluronic as classic pore precursors on the structure of obtained scaffolds was analyzed. It was shown that the addition of gelatin non‐wovens enables the preparation of scaffolds, which allow for the growth of cells (size, distribution, and shape of pores). Mechanical properties of the obtained cell scaffolds were determined. The influence of pore precursors on mass absorption of scaffolds against isopropanol and plasma was investigated. Interaction of scaffolds with a T‐lymphocyte line (Jurkat) and with fibroblasts (L929) was investigated. Obtained scaffolds are not cytotoxic and can be used as implants, for example, the regeneration of cartilage tissue.

Keywords:
cell cultures, cytotoxic, fibroblasts, imprinted scaffolds

Abstract:
Results of the preparation of semi-permeable membranes made of biodegradable polymers membranes were presented. Among known polyesters, polylactide was selected for research. The membranes were obtained using wet phase inversion method. The influence of polyvinylpyrrolidone and polymeric nano-non-wovens as pores precursors on the structure of obtained membranes was analysed. It was shown, that utilisation of polymeric nano-non-wovens enabled preparation of semi-permeable membranes, which could be used as wide-pore 3D-type cellular scaffolds.

Keywords:
Biodegradable polymers membranes, Biodegradable polyesters, Porous three-dimensional scaffolds, Inversion phase method

Abstract:
Three types of membrane structures with wide pores were compared in this study. One of the membranes was obtained from polyethersulfone using cellulose fibers as the macropore precursors. Two of the fibers were obtained from poly(L-lactide). As the macropore precursors olyvinylpyrrolidone (1.2 MDa) and pork gelatin non-woven were used, the influence of non-woven fibers on the structure of membranes was shown. Necessity of specific membrane structure application was explained. The hoice of polymers and co-polymers with a range of biodegradation times can determine the scaffold type suitable for the age of a patient.

Keywords:
Polysulfone membrane, Polyester membranes, Membrane structures, Biodegradable membranes, 3D scaffold