Cartilage is a tension- and load-bearing tissue and has a limited capacity for intrinsic self-healing. While microfracture and arthroplasty are the conventional methods for cartilage repair, these methods are unable to completely heal the damaged tissue. The need to overcome the restrictions of these therapies for cartilage regeneration has expanded the field of cartilage tissue engineering (CTE), in which novel engineering and biological approaches are introduced to accelerate the development of new biomimetic cartilage to replace the injured tissue. Until now, a wide range of hydrogels and cell sources have been employed for CTE to either recapitulate microenvironmental cues during a new tissue growth or to compel the recovery of cartilaginous structures via manipulating biochemical and biomechanical properties of the original tissue. Towards modifying current cartilage treatments, advanced hydrogels have been designed and synthesized in recent years to improve network crosslinking and self-recovery of implanted scaffolds after damage in vivo. This review focused on the recent advances in CTE, especially self-healing hydrogels. The article firstly presents the cartilage tissue, its defects, and treatments. Subsequently, introduces CTE and summarizes the polymeric hydrogels and their advances. Furthermore, characterizations, the advantages, and disadvantages of advanced hydrogels such as multi-materials, IPNs, nanomaterials, and supramolecular are discussed. Afterward, the self-healing hydrogels in CTE, mechanisms, and the physical and chemical methods for the synthesis of such hydrogels for improving the reformation of CTE are introduced. The article then briefly describes the fabrication methods in CTE. Finally, this review presents a conclusion of prevalent challenges and future outlooks for self-healing hydrogels in CTE applications.

In this research physico-mechanical properties including tensile strength, elongation at break, hardness, resilience, abrasion resistance, and compression set of unsaturated natural rubber and styrene butadiene rubber (NR/SBR) alloy cured by sulfur curing system were investigated. Factorial design method was employed in order to formulate the sulfur curing system. Three different curing agents were used and their effects on physico-mechanical properties of the alloy were investigated. The results show that with increasing each curing agent, curing time and scorch time reduce and maximum torque increases. Tensile strength, % elongation at break, tear strength, and compression set decrease while hardness, resilience, and abrasion increase. The results show that application of factorial design significantly reduces research and development costs by decreasing the number of experimental configurations to be studied and the results are accurate. Results from factorial design procedure very well match the experimental results with accuracy in order of 2% variations.