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The lack of adequate blood/lymphatic vessels as well as low-potential articular cartilage regeneration underlines the necessity to search for alternative biomaterials. Owing to their unique features, such as reversible thermogelling behavior and tissue-like mechanical behavior, agarose-based biomaterials have played a key role in cartilage tissue repair. Accordingly, the need for fabricating novel highly efficient injectable agarose-based biomaterials as hydrogels for restoration of injured cartilage tissue has been recognized. In this review, the resources and conspicuous properties of the agarose-based biomaterials were reviewed. First, different types of signals together with their functionalities in the maintenance of cartilage homeostasis were explained. Then, various cellular signaling pathways and their significant role in cartilage tissue engineering were overviewed. Next, the molecular structure and its gelling behavior have been discussed. Eventually, the latest advancements, the lingering challenges, and future ahead of agarose derivatives from the cartilage regeneration perspective have been discussed.

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Polyetheramine (PEA)-modified epoxies with various types of PEAs were prepared and respective effects on characteristics of epoxy networks were studied. The used PEAs were polyethylene glycol diamine (PEG-amine) and polypropylene glycol diamine (PPGamine) with two different molecular weights (i.e., 200 and 400 g mol −1 ). According to mechanical tests, the structural parameters of PEAs played an important role in final properties of epoxy/amine systems. PEG 400 -amine and PPG 200 -amine had the highest and lowest effects on the properties of epoxy networks, respectively. Whereas 10 phr PEG 400 -amine increased critical stress intensity factor (K IC ) and critical strain energy release rate (G IC ) of the epoxy up to 82 and 294%, the same number of PPG 200 -amine chains caused to increase the K IC and G IC up to 11 and 34%. This discrepancy could be assigned to higher flexibility index (φ = 26.22), longer chain length (~27 atoms), and higher secondary interactions [δ = 9.69 (cal cm −3 ) 0.5 ] of PEG 400 -amine in comparison with PPG 200 -amine [with φ = 8.08,~10 atoms in chain, and δ = 8.98 (cal cm −3 ) 0.5 ]. Shear yielding as a toughening mechanism was proposed based on microscopy of the crack tips. These in-depth studies could uncover underlying structure-property relationships in a relevant class of PEA-like modifiers, shedding light on the future design of top-performing homogeneous tough polymer networks.

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