“…Its peaks indicating C=O asymmetric bonds (1590 cm −1 ), as well as symmetric (1405 cm −1 ) stretching vibration are clearly visible. Additionally, peaks at 1300 cm −1 and 1020 cm −1 , which are known to relate to the C-O stretching vibration of the carboxyl groups, are present in the spectrum at 1296 cm −1 and 1028 cm −1 , respectively [ 35 ]. In comparison to pure ADA, additional peaks can be found in the ADA-GEL spectrum.…”
A hydrogel system based on oxidized alginate covalently crosslinked with gelatin (ADA-GEL) has been utilized for different biofabrication approaches to design constructs, in which cell growth, proliferation and migration have been observed. However, cell–bioink interactions are not completely understood and the potential effects of free aldehyde groups on the living cells have not been investigated. In this study, alginate, ADA and ADA-GEL were characterized via FTIR and NMR, and their effect on cell viability was investigated. In the tested cell lines, there was a concentration-dependent effect of oxidation degree on cell viability, with the strongest cytotoxicity observed after 72 h of culture. Subsequently, primary human cells, namely fibroblasts and endothelial cells (ECs) were grown in ADA and ADA-GEL hydrogels to investigate the molecular effects of oxidized material. In ADA, an extremely strong ROS generation resulting in a rapid depletion of cellular thiols was observed in ECs, leading to rapid necrotic cell death. In contrast, less pronounced cytotoxic effects of ADA were noted on human fibroblasts. Human fibroblasts had higher cellular thiol content than primary ECs and entered apoptosis under strong oxidative stress. The presence of gelatin in the hydrogel improved the primary cell survival, likely by reducing the oxidative stress via binding to the CHO groups. Consequently, ADA-GEL was better tolerated than ADA alone. Fibroblasts were able to survive the oxidative stress in ADA-GEL and re-entered the proliferative phase. To the best of our knowledge, this is the first report that shows in detail the relationship between oxidative stress-induced intracellular processes and alginate di-aldehyde-based bioinks.
“…Its peaks indicating C=O asymmetric bonds (1590 cm −1 ), as well as symmetric (1405 cm −1 ) stretching vibration are clearly visible. Additionally, peaks at 1300 cm −1 and 1020 cm −1 , which are known to relate to the C-O stretching vibration of the carboxyl groups, are present in the spectrum at 1296 cm −1 and 1028 cm −1 , respectively [ 35 ]. In comparison to pure ADA, additional peaks can be found in the ADA-GEL spectrum.…”
A hydrogel system based on oxidized alginate covalently crosslinked with gelatin (ADA-GEL) has been utilized for different biofabrication approaches to design constructs, in which cell growth, proliferation and migration have been observed. However, cell–bioink interactions are not completely understood and the potential effects of free aldehyde groups on the living cells have not been investigated. In this study, alginate, ADA and ADA-GEL were characterized via FTIR and NMR, and their effect on cell viability was investigated. In the tested cell lines, there was a concentration-dependent effect of oxidation degree on cell viability, with the strongest cytotoxicity observed after 72 h of culture. Subsequently, primary human cells, namely fibroblasts and endothelial cells (ECs) were grown in ADA and ADA-GEL hydrogels to investigate the molecular effects of oxidized material. In ADA, an extremely strong ROS generation resulting in a rapid depletion of cellular thiols was observed in ECs, leading to rapid necrotic cell death. In contrast, less pronounced cytotoxic effects of ADA were noted on human fibroblasts. Human fibroblasts had higher cellular thiol content than primary ECs and entered apoptosis under strong oxidative stress. The presence of gelatin in the hydrogel improved the primary cell survival, likely by reducing the oxidative stress via binding to the CHO groups. Consequently, ADA-GEL was better tolerated than ADA alone. Fibroblasts were able to survive the oxidative stress in ADA-GEL and re-entered the proliferative phase. To the best of our knowledge, this is the first report that shows in detail the relationship between oxidative stress-induced intracellular processes and alginate di-aldehyde-based bioinks.
“…The cavity structure inside G2 PAMAM-H allows it to be used as a physical cross-linking of the rubber molecular chain. Point, when the dendrimers interact with each other, G2 PAMAM and G2 PAMAM-H can drive the rubber molecular chain to move, and endowed CIIR with unique self-healing properties [ 38 , 39 ]. Figure 7.…”
Section: Resultsmentioning
confidence: 99%
“…The reversible multiple hydrogen bonds formed enhanced interactions between the two cutting and separated interfaces.The cavity structure inside G2 PAMAM-H allows it to be used as a physical cross-linking of the rubber molecular chain. Point, when the dendrimers interact with each other, G2 PAMAM and G2 PAMAM-H can drive the rubber molecular chain to move, and endowed CIIR with unique self-healing properties [38,39]. The cavity of G2 PAMAM-H was assumed to be spherical.…”
Section: 5self-healing Performance Of Ciir/g2 Pamam-h Nanocompositesmentioning
Based on its excellent damping properties, traditional rubber has been widely used in various industries, including aerospace, rail transit and automotive. However, the disadvantages of effective damping area, unstable damping performance, easy fatigue, and aging, greatly limited the further application of rubber materials. Thus, it is important to develop novel modified rubber damping materials. Herein, polyamidoamine dendrimers with terminal-modified phenolic hydroxyl and amine groups (G2 PAMAM-H) were designed and used as modifiers to improve the damping performance of chlorinated butyl rubber (CIIR). The results showed that the modification of G2 PAMAM by diphenolic acid can avoid its aggregation in the CIIR matrix. CIIR/G2 PAMAM-H nanocomposites exhibited high tan
δ
max
of 1.52 and wide damping temperature region of 140°C (tan
δ
> 0.55)at a very low loading (4.32 wt.%), which were strongerthan that of pure CIIR and CIIR/G2 PAMAM nanocomposites. In addition, these nanocomposites also exhibited a unique self-healing ability by multiple hydrogen bonds, which can effectively extend the life of the rubber material in actual production. Therefore, the dendrimer modification provided unique development opportunities for elastomers in certain highly engineered fields, such as vehicles, rail transit, aerospace, etc.
“…Therefore, self-repairing flexible materials with multiple repair systems emerge as the times require. [76][77][78][79][80][81] Lu and Zhang et al developed a self-healing electronic sensor with high stability and repeatability based on metal coordination and layered structure. After more than 50 000 times of bending or repeated washing, the strain sensor still has excellent mechanical properties.…”
“…Therefore, self‐repairing flexible materials with multiple repair systems emerge as the times require. [ 76–81 ] Lu and Zhang et al. developed a self‐healing electronic sensor with high stability and repeatability based on metal coordination and layered structure.…”
related operations, and destroy the operation of the whole equipment (system). Bao and his colleagues developed a novel self-healing and mechanical force-sensing flexible sensor using micro-structured elastomeric dielectrics, which served as a foundation to improve the stability and lifetime of flexible sensors. [8] Self-healing flexible materials can be divided into two categories, one is solvent-less or water-free after curing and high degree of polymerization of elastomers, such as polyamide, polyurethane, etc., the other is hydrogels, low degree of polymerization, structural cross-linking. In self-healing flexible elastomer sensors, the structure of elastomer is mostly linear structure or semi-cross-linked structure; the elastomer of cross-linked structure is poor flexibility and fragile due to its high degree of polymerization. The elasticity of semi-crosslinked structure has excellent resilience and great potential in the field of flexible flexural sensors. In the past two years, self-healing flexible hydrogels have attracted extensive attention due to their excellent stretchability and resilience, as well as outstanding performance in the preparation of sensors with high sensitivity and fast response. [9,10] Sensors with elastomers and hydrogels as flexible matrices face great difficulties in conductivity, which affects the sensitivity and stability of the sensors. Filling conductive materials is the most commonly method, in which organic conductive polymers (polyaniline, [11] polypyrrole [12]) are filled to construct conductive networks, and good interfacial compatibility results in uniform conductive polymer elastomers, but the inherent color fillers affect the transparency of flexible sensors, limiting their applications in the biomedical field. [13-17] Flexible materials filled with inorganic conductive particles (graphene, nano-silver wire) have high conductivity, but phase separation between filler and matrix usually reduces the tensile, toughness and fatigue resistance, and even affects the self-healing ability of flexible materials. Modified fillers are often required to improve affinity for flexible matrices and inhibit phase separation. However, many hydrogel matrices are intrinsically weak and cannot withstand cyclic loadings. [18] Although surface modified fillers can improve strength and toughness, it is difficult to compensate for the inherent weaknesses. For self-healing flexible elastomers, conductive flexible materials can still be endowed with conductivity by scraping or printing conductive particles on the Flexible pressure and strain sensors have great potential for applications in wearable and implantable devices, soft robots, and artificial skin. The introduction of self-healing performance has made a positive contribution to the lifetime and stability of flexible sensors. At present, many self-healing flexible sensors with high sensitivity have been developed to detect the signal of organism activity. The sensitivity, reliability, and stability of self-healing flexible sensors depend...
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