Into the Tissues: Extracellular Matrix and Its Artificial Substitutes: Cell Signalling Mechanisms

The existence of orderly structures, such as tissues and organs is made possible by cell adhesion, i.e., the process by which cells attach to neighbouring cells and a supporting substance in the form of the extracellular matrix. The extracellular matrix is a three-dimensional structure composed of collagens, elastin, and various proteoglycans and glycoproteins. It is a storehouse for multiple signalling factors. Cells are informed of their correct connection to the matrix via receptors. Tissue disruption often prevents the natural reconstitution of the matrix. The use of appropriate implants is then required. This review is a compilation of crucial information on the structural and functional features of the extracellular matrix and the complex mechanisms of cell–cell connectivity. The possibilities of regenerating damaged tissues using an artificial matrix substitute are described, detailing the host response to the implant. An important issue is the surface properties of such an implant and the possibilities of their modification

Biomimetic scaffolds based on chitosan in bone regeneration. A review

Chitosan (CS) is a polysaccharide readily used in tissue engineering due to its properties: similarity to the glycosaminoglycans present in the body, biocompatibility, non-toxicity, antibacterial character and owing to the fact that its degradation that may occur under the influence of human enzymes generates non-toxic products. Applications in tissue engineering include using CS to produce artificial scaffolds for bone regeneration that provide an attachment site for cells during regeneration processes. Chitosan can be used to prepare scaffolds exclusively from this polysaccharide, composites or polyelectrolyte complexes. A popular solution for improving the surface properties and, as a result enhancing cell-biomaterial interactions, is to coat the scaffold with layers of chitosan. The article focuses on a polysaccharide of natural origin – chitosan (CS) and its application in scaffolds in tissue engineering. The last part of the review focuses on bone tissue and interactions between cells and chitosan after implantation of a scaffold and how chitosan’s structure affects bone cell adhesion and life processes

Rapid and Efficient Optimization of Poly(1,2-Ethanediol Citrate) Synthesis Based on Magic Squares’ Various Methods

New biomaterials among aliphatic polyesters are in demand due to their potential applications in tissue engineering. There is a challenge not only to design scaffolds to regenerate defects in load-bearing tissues but also to ensure a proper blood supply to the reconstructed tissues. Poly-(1,2-ethanediol citrate) is one of the novel citrate-based polymers that could have the desired properties for cell scaffold fabrication and for enhancing cell adhesion. Both citric acid and 1,2-ethanediol are used in medicine and are fully resorbable by cells. This work aimed to synthesize poly(1,2-ethanediol citrate) in a catalyzed reaction with water removed by the Dean–Stark apparatus. The polyester structure was characterized by FTIR and NMR spectroscopy, and the HMBC experiment was performed to support the theory of successful polymer synthesis. The molecular weight was determined for the products obtained at 140 °C. The process was described via non-linear mathematical models. The influence of temperature and catalyst content on the degree of esterification and the conversion of acid groups in citric acid is described. The optimal process parameters are determined at 140 °C and 3.6% of p-toluenesulfonic acid content. The presented results are the starting point for scaffold design and scaling-up the process

Manufacturing of substitutes for spongy bone with increased absorbability

Composite scaffolds with increased hydrophilicity were prepared for cancellous bone regeneration by the freeze-extraction method. As a construction material, a poly–L–lactide (PLLA) was applied. As a hydrophilic, modifying agent a methacrylic acid copolymer, trade name Eudragit, was used. Apreliminary investigation and optimization of the processwere performed. For the obtained scaffolds, regression equations determining the effect of: EudragitE100/PLLA weight ratio; volume ratio of methanol (porophore)/PLLA solution in dioxane on interconnected porosity and mass absorbability of obtained implants were calculated

Kinetics of PTSA-Catalysed Polycondensation of Citric Acid with 1,3-Propanediol

Recent years have seen the intensive development of novel therapies based on stem cells and advanced materials. Among the latter, polymers, especially polyesters, occupy a special place and are being investigated for use as substrates for cell differentiation and culture. Increasing application requirements are driving demand for such materials. This study aims to obtain a new material with potential biomedical applications, poly(1,3-propanediol citrate). A spectral analysis of the obtained product was carried out. The reaction kinetics of the polycondensation of citric acid and 1,3-propanediol in the presence of a catalyst, p-toluenesulphonic acid (PTSA), are described. The basis for determining the polycondensation kinetics was the assumption of non-equivalence of the carboxyl groups in citric acid. Elementary reaction rate constants and activation energy values were determined. Based on the data obtained, the course of the gelation points of the reaction mixture was estimated in its dependence on the temperature and reaction time. Kinetic research will facilitate the scale-up of the process

Optimisation of Glycerol and Itaconic Anhydride Polycondensation

Glycerol polyesters have recently become objects of interest in tissue engineering. Barely known so far is poly(glycerol itaconate) (PGItc), a biocompatible, biodegradable polyester. Due to the presence of a C=C electron-acceptor moiety, it is possible to post-modify the product by Michael additions to change the properties of PGItc. Thus, using PGItc as one of the elements of cellular scaffold crosslinked in situ for bone tissue regeneration seems to be a very attractive yet unexplored solution. This work aims to optimize the synthesis of PGItc to obtain derivatives with a double bond in the side chain with the highest conversion rates. The experiments were performed with itaconic anhydride and glycerol using mathematical planning of experiments according to the Box-Behnken plan without solvent and catalyst. The input variables of the process were the ratio of the OH/COOH, temperature, and reaction time. The optimised output variables were: the degree of esterification (EDtitr), the degree of esterification calculated from the analysis of 1H NMR spectra (EDNMR), and the degree of itaconic anhydride conversion—calculation based on 13C NMR spectra (%X13CNMR). In each of statistical models, the significance of the changed synthesis parameters was determined. Optimal conditions are when OH/COOH ratio is equal to 1.5, temperature is 140 °C and time of reaction is 5 h. The higher OH/COOH ratio, temperature and longer the experiment time, the higher the value of the degree of esterification and the degree of anhydride conversion

Kinetics of PTSA-Catalysed Polycondensation of Citric Acid with 1,3-Propanediol

Recent years have seen the intensive development of novel therapies based on stem cells and advanced materials. Among the latter, polymers, especially polyesters, occupy a special place and are being investigated for use as substrates for cell differentiation and culture. Increasing application requirements are driving demand for such materials. This study aims to obtain a new material with potential biomedical applications, poly(1,3-propanediol citrate). A spectral analysis of the obtained product was carried out. The reaction kinetics of the polycondensation of citric acid and 1,3-propanediol in the presence of a catalyst, p-toluenesulphonic acid (PTSA), are described. The basis for determining the polycondensation kinetics was the assumption of non-equivalence of the carboxyl groups in citric acid. Elementary reaction rate constants and activation energy values were determined. Based on the data obtained, the course of the gelation points of the reaction mixture was estimated in its dependence on the temperature and reaction time. Kinetic research will facilitate the scale-up of the process

Optimizing the conditions of PGSu synthesiswith simplex method

Poly(glycerol succinate) – PGSu – is one of glycerol polyesters which has focused nowadays the interestof scientists developing new biomaterials. Probably the polyester could be used as a drug carrier or asa cell scaffold in tissue engineering. Due to its potential use in medicine, it is extremely important todevelop a synthesis and then optimize it to obtain a material with desired properties. In this work oneflask two-step polycondensation of glycerol and succinic anhydride to PGSu is presented. Synthesiswas optimized with the simplex method and also described using a second-degree equation with twovariables (temperature and time) to better find the optimum conditions. PGSu was characterized byFTIR spectroscopy, NMR spectroscopy, degree of esterification was determined, and also molecularweight was calculated for each experiment using Carothers equation. A new synthesis route wasdeveloped and optimized. Temperature and time influence on molecular weight and esterificationdegree of obtained polyester are presented. Based on experiments conducted in this work, it waspossible to obtain poly(glycerol succinate) with molecular weight of 6.7 kDa

Ocena właściwości antymikrobiologicznych proleków chlorofenezyny

Spheres of prodrug of polylactide (PLA) or polycaprolactone (PCL) or a copolymer thereof with chlorphenesin (CF) were obtained. Furthermore spheres with an active substance additionally dispersed in the prodrug matrix – hybrid spheres – were prepared. The antimicrobial properties of the prodrug forms obtained were investigated towards bacteria, yeast, and filamentous fungi to verify whether the CF activity of the new formulations maintains. This research shows a wide spectrum of antimicrobiological application, especially when using CF as a preservative.Otrzymano sfery z proleku chlorofenezyny (CF) i polilaktydu (PLA), polikaprolaktonu (PCL) lub ich kopolimeru, a także sfery hybrydowe z substancją aktywną dodatkowo rozproszoną w matrycy proleku. W celu sprawdzenia, czy aktywność CF została zachowana, zbadano właściwości antymikrobiologiczne wszystkich otrzymanych form proleku wobec bakterii, drożdży i grzybów strzępkowych. Uzyskane wyniki wskazują na możliwe szerokie spektrum aplikacji tych form leku, szczególnie w charakterze konserwantu