Peritoneal adhesions are highly important in clinical and surgical practice because of the potential to cause sequelae such as chronic abdominal pain, infertility and bowel obstruction; thus, preventing the formation of this process becomes a challenge for surgeons. Due to biocompatibility, bioabsorption, healing and antimicrobial properties, chitosan is a polymer which has aroused interest of researchers studying the prevention of peritoneal adhesions. The objective of this research was to determine whether the intraperitoneal implantation of polypropylene mesh coated with a film of chitosan/polyethylene glycol is effective for the prevention of adhesions in rats with induced abdominal defects. We sought to further characterize the tissue reactions in acute and chronic phases of the inflammation process, and the tissue repair processes triggered by this biomaterial and the polypropylene mesh without coating. Defect of about 1cm was made in the abdominal wall, with reference to anatomical aponeurosis of the fascia of the rectus abdominis and obliquus externus abdominis muscles, followed by the implantation of polypropylene meshes coated with chitosan / polyethylene glycol (QP Group, n= 12) and uncoated polypropylene meshes (PP group, n= 12). Six animals from each group were euthanized at four and 45 days after implantation and the involvement of the mesh area by the adhesion, the type of adhesion, the inflammation process and tissue repair, and the quantification and characterization of collagen fibers were evaluated. The average of the meshes involved by adhesions in the QP and PP groups was 39.088% and 84.024%, respectively, and the structure involved in abdominal adhesions in the QP group usually consisted of the omentum around the implant, while in the PP group, adhesions were usually on the surface of the mesh. After four days of surgery, the amount of mononuclear cells was lower in QP, but the amount of polymorphonuclear cells, fibrin and collagen fibers was in greater quantity in this group; besides, the later variable showed better spatial organization. After 45 days of biomaterials implantation, there was a reduction in the amount of inflammatory cells, and spatial organization of collagen fibers in the QP group remained strong. It is concluded that the meshes coated with the film based on chitosan/polyethylene glycol did not prevent adhesion formation, but significantly minimized the seriousness of this process. In the acute phase of inflammation and tissue repair, the foreign body reaction was less intense in the group receiving the coated polypropylene mesh, but the tissue reactions caused by the studied biomaterials were similar to the chronic phase. The mesh coated with film-based chitosan/polyethylene glycol stimulated higher production and better orientation of collagen type I in the acute phase of inflammation and tissue repair, and better orientation of collagen fibers in the chronic phase of this process.

O combate à poluição gerada pela indústria da moda, assim como outros fatores sociopolíticos e económicos agregados a este problema serve de propósito para o aprofundamento da sustentabilidade neste setor. Esta crise leva a procura de soluções através da interdisciplinaridade onde incorre o desenvolvimento do biodesign. Deste é fruto o tema dos biomateriais, que se provam como uma inovação promissora na área têxtil. É com base neste propósito que se levanta a questão de investigação que recai sobre a existência de um biomaterial viável para uso na indústria têxtil. Já foram abordados vários tipos de biomateriais no contexto de moda como a kombucha, a gelatina ou o agar-agar, contudo o objetivo geral deste estudo irá incidir na exploração do alginato de sódio como um biomaterial capaz de insurgir na indústria da moda como uma alternativa a materiais que são poluentes. Através desta investigação é recolhida informação já existente sobre o alginato de sódio e de biomateriais de forma a poder entendê-los, para os poder recriar, observar, analisar, criar e manipular as suas características (cores, formas, propriedades, design têxtil, design, cheiro, toque). O culminar do projeto resulta no desenvolvimento de diversas amostras e a reprodução aumentada de uma destas para o desenvolvimento de um protótipo de bio têxtil que pode servir como alternativa viável a matérias poluentes utilizados na indústria têxtil, com a finalidade de poderem ser peças circulares, podendo decompor-se de forma a não criar desperdício.

Stereolithography is an additive technique that produces three-dimensional (3D) solid objects using a multi-layer procedure through the selective photoinitiated curing reaction of a liquid photosensitive material. Stereolithographic processes have been widely employed in Tissue Engineering for the fabrication of temporary constructs, using natural and synthetic polymers, and polymer-ceramic composites. These processes allow the fabrication of complex structures with a high accuracy and precision at physiological temperatures, incorporating cells and growth factors without significant damage or denaturation. Despite recent advances on the development of novel biomaterials and biocompatible crosslinking agents, the main limitation of these techniques are the lack number of available photocrosslinkable materials, exhibiting appropriate biocompatibility and biodegradability. This chapter gives an overview of the current state-of-art of materials and stereolithographic techniques to produce constructs for tissue regeneration, outlining challenges for future research.

Three‐dimensional (3D) bioprinting comprises a group of biofabrication technologies for the additive manufacturing of 3D constructs by precisely printing biocompatible materials, cells and biochemicals in predesigned spatial positions. These technologies have been successfully applied to fabricate biodegradable 3D constructs with intricate architectures and heterogeneous composition, assuming a pivotal role in the field of tissue engineering. However, the full implementation of bioprinting strongly depends on the development of novel biomaterials exhibiting fast crosslinking schemes and appropriate printability, cell‐compatibility and biomechanical properties. Photocrosslinkable hydrogels are attractive materials for bioprinting as they provide fast polymerization under cell‐compatible conditions and exceptional spatiotemporal control over the gelation process. Photopolymerization can also be performed during the bioprinting to promote the instantaneous formation of hydrogel with high well‐defined architecture and structural stability. In this review paper, we summarize the most recent developments on bioprinting of photocrosslinkable biodegradable hydrogels for tissue engineering, focusing on the chemical modification strategies and the combination of photocrosslinking reactions with other gelation modalities.

The in vivo degradation processes by which scaffolds degrade and are replaced by neo-tissue are complex and may be influenced by many factors, including environmental conditions, material properties, porosity and 3D architecture. The present study is focused on the influence of design parameters, filament distance (FD) and lay-down pattern, on the degradation kinetics of Polycaprolactone (PCL) scaffolds obtained via BioExtrusion. Through the variation of design parameters it was possible to obtain two groups of scaffolds with distinct pore geometry and size. The in vitro degradation was performed in simulated body fluid (SBF) and in phosphate buffer solution (PBS) for six months. Our results highlight a more complex degradation pattern of the scaffolds in SBF than in PBS, probably related to a mineral deposition. Significant statistical differences in weight loss values at month 6, allowed us to conclude that degradation kinetics of PCL scaffolds is strongly influenced by the pore size.

The most promising strategies in tissue engineering involve the integration of a triad of biomaterials, living cells, and biologically active molecules to engineer synthetic environments that closely mimic the healing milieu present in human tissues, and that stimulate tissue repair and regeneration. To be clinically effective, these environments must replicate, as closely as possible, the main characteristics of the native extracellular matrix (ECM) on a cellular and subcellular scale. Photo-fabrication techniques have already been used to generate 3D environments with precise architectures and heterogeneous composition, through a multi-layer procedure involving the selective photocrosslinking reaction of a light-sensitive prepolymer. Cells and therapeutic molecules can be included in the initial hydrogel precursor solution, and processed into 3D constructs. Recently, photo-fabrication has also been explored to dynamically modulate hydrogel features in real time, providing enhanced control of cell fate and delivery of bioactive compounds. This paper focuses on the use of 3D photo-fabrication techniques to produce advanced constructs for tissue regeneration and drug delivery applications. State-of-the-art photo-fabrication techniques are described, with emphasis on the operating principles and biofabrication strategies to create spatially controlled patterns of cells and bioactive factors. Considering its fast processing, spatiotemporal control, high resolution, and accuracy, photo-fabrication is assuming a critical role in the design of sophisticated 3D constructs. This technology is capable of providing appropriate environments for tissue regeneration, and regulating the spatiotemporal delivery of therapeutics.

Tissue engineering, often referred to as regenerative medicine and reparative medicine, is an interdisciplinary field that necessitates the combined effort of cell biologists, engineers, material scientists, mathematicians, geneticists, and clinicians toward the development of biological substitutes that restore, maintain, or improve tissue function. It has emerged as a rapidly expanding approach to address the organ shortage problem and comprises tissue regeneration and organ substitution. Cells placed on/or within constructs is the most common strategy in tissue engineering. Successful cell seeding depends on fast attachment of cell to scaffolds, high cell survival and uniform cell distribution. The seeding time is strongly dependent on the scaffold material and architecture. Scaffolds provide an initial biochemical substrate for the novel tissue until cells can produce their own extra-cellular matrix (ECM). Thus scaffolds not only define the 3D space for the formation of new tissues, but also serve to provide tissues with appropriate functions. These scaffolds are often critical, both in vivo (within the body) or in vitro (outside the body) mimicking in vivo conditions. Additive fabrication processes represent a new group of non-conventional fabrication techniques recently introduced in the biomedical engineering field. In tissue engineering, additive fabrication processes have been used to produce scaffolds with customised external shape and predefined internal morphology, allowing good control of pore size and pore distribution. This article provides a comprehensive state-of-the-art review of the application of biomanufacturing additive processes in the field of tissue engineering. New and moving trends in biomanufacturing technologies and the concept of direct cell-printing technologies are also discussed.

Objective: The aim of this study was to investigate the healing effect of advanced platelet-rich fibrin (A-PRF) clot membranes in palatal wounds, resulting from free gingival graft (FGG) harvesting, on the reepithelization rate and on the pain experience after surgery. Materials and Methods: Twenty-five patients requiring FGG have participated in this prospective cohort study. After FGG harvesting, the test group (n = 14) received A-PRF clot membranes at the palatal wound and the control group (n = 11) received a gelatin sponge. Epithelialization rate of the palatal wound, wound healing area, correspondent percentage of reduction, and postsurgical pain experience were assessed at 2, 7, 14, 30, and 90 days. Results: A-PRF group had higher palatal wound reduction than the control group, at 7, 14, and 30 days of follow-up. The highest difference between the groups was attained at 30 days (91.5% for A-PRF vs. 59.0% control group). At 14 days, a significant difference in the proportion of patients showing total epithelization was found: 64.3% for A-PRF versus 9.1% for the control group. At 90 days, both groups showed total recovery. The control group experienced higher pain level and discomfort until the 14th day, being notably higher on the second day. Conclusion: The results suggest that A-PRF membranes haste the healing process, and promote greater reduction along the recovery period and less painful postoperative period.

To compare the adhesive interface of eroded dentin formed by a functional dental adhesive and a gold standard strategy, by testing microtensile bond strength (μTBS), hardness/elastic modulus. Permanent sound human molars were randomly allocated to four experimental groups, all subject to artificial erosion (0.05 M citric acid; 3× daily, 5 days). Groups included control Clearfil SE Bond 2 (CFSE), and experimental group Clearfil SE Protect (CFP), at two different time points-immediate (24 h) and long term (3 months–3 M). Samples were sectioned into microspecimens for μTBS (n = 8) and into 2-mm thick slabs for nanoindentation assays (n = 3). Groups CFSE_3M and CFP_3M were stored in artificial saliva. Statistical analysis included two-way ANOVA for μTBS data, while hardness/modulus results were analyzed using Kruskal–Wallis H Test (significance level of 5%; SPSS v.27.0). Although no significant differences were found between mean μTBS values, for different adhesives and time points (p > 0.05), a positive trend, with μTBS rising in the CFP_3M group, was observed. Regarding hardness, no significant differences were seen in the hybrid layer, considering the two variables (p > 0.05), while the reduced elastic modulus rose in CFP_3M when compared to 24 h. Thus, CFP shows similar mechanical and adhesive performance to CFSE in eroded dentin, although it may comprise promising long-term results. This is advantageous in eroded substrates due to their increased enzymatic activity and need for remineralization.

The aim of this study is to compare the adhesive interface formed in dentin, using self-adhesive composites applied with different bonding strategies, by testing the microtensile bond strength (μTBS) and ultramorphology through the use of light microscopy. Permanent, sound human molars were randomly allocated to six experimental groups. The groups included a negative control group, where only etching was performed via EtchOnly; a positive control group where an adhesive was applied, OptiBondFL (OBFL); and an experimental group where a primer was applied using a co-curing strategy together with a composite (Primer_CoCuring). The samples were sectioned into microspecimens for μTBS (n = 8) and into 1-mm thick slabs for light microscopy using Masson’s trichrome staining protocol (n = 3). The statistical analysis included a two-way ANOVA for μTBS data and Tukey’s HSD was used as a post-hoc test (significance level of 5%; SPSS v. 26.0). The results of the μTBS revealed that the self-adhesive composite (F = 6.0, p < 0.018) and the bonding strategy (F = 444.1, p < 0.001) significantly affected the bond strength to dentin. However, their interactions were not significant (F = 1.2, p = 0.29). Etching dentin with no additional treatment revealed the lowest μTBS (VF_EtchOnly = 2.4 ± 0.8 MPa; CC_EtchOnly = 2.0 ± 0.4 MPa), which was significantly different from using a primer (VF_CoCu = 8.8 ± 0.8 MPa; CC_CoCu = 6.3 ± 1.0 MPa) or using the full adhesive (VF_OptiBondFL = 22.4 ± 0.3 MPa; CC_OptibondFL = 21.2 ± 0.4 MPa). Microscopy images revealed that the experimental Primer_CoCuring was the only group with no collagen fibers exposed to the dentin–composite interface. Overall, the use of a primer, within the limitations of this study, increased the bonding of the self-adhesive composite and provided sufficient infiltration of the collagen based on light-microscopic imaging.