Cartilage-Inspired Hydrogel with Mechanical Adaptability, Controllable Lubrication, and Inflammation Regulation Abilities

Abstract

Cartilage is a key component in joints because of its load-bearing and lubricating abilities. However, osteoarthritis often leads to afunction of load-bearing/lubrication and occurrence of inflammation with overexpressed reactive oxygen species (ROS) and nitric oxide (NO). To address these issues, we fabricated a novel polyanionic hydrogel with abundant carboxylates/sulfonates ("CS" hydrogel), inspired by normal cartilage rich in anionic hyaluronate/sulfonate glycosaminoglycan/lubricin, and crosslinked it tightly by Fe 3+ ("CS-Fe" hydrogel). The "CS-Fe" hydrogel displayed mechanical adaptability and shear resistance. A low coefficient of friction (∼0.02) appeared when a loose hydrogel layer was generated because of the photoreduction of Fe 3+ to Fe 2+ by UV irradiation. This biocompatible "CS-Fe" hydrogel suppressed the overexpressed hydroxyl radical (•OH) and NO in macrophages and protected chondrocytes/fibroblasts from aggressive inflammation. Moreover, the layered "CS-Fe" hydrogel avoided cell death of chondrocytes in sliding tests. The results demonstrate that this cartilage-inspired hydrogel is a promising candidate material in cartilage tissue engineering to especially address inflammation.

Al3+ Cofactor Evoking Iron Porphyrin-AuNP Hybrids as Oxidase-Mimicking Nanozymes with Prominent Catalytic Efficiency in a Broad pH Range

“…Expectedly, the addition of ascorbic acid (a reducing agent) to the Fe II -TCPP-AuNP/Al 3+ system treated with potassium permanganate restores the oxidase-mimicking activity (Figure D). KMnO 4 oxidizes the ferrous ion in the Fe II -TCPP-AuNP/Al 3+ system, and the addition of AA partially reduces the ferric Fe II -TCPP to ferrous Fe II -TCPP. − This reversible regulation process further confirms that ferrous Fe II -TCPP plays an important role in the oxidase-mimicking activity of the Fe II -TCPP-AuNP/Al 3+ system, which is consistent with natural oxygenases. Fe 3+ is reduced to Fe 2+ after FeTCPP binding on the AuNP surface, which has been demonstrated by the above XPS and UV–vis spectroscopy results.…”

Articular Cartilage-Inspired Hybrid Double-Network Hydrogels with a Layered Structure and Low Friction Properties

“…Yu et al developed a layered "CS-Fe" hydrogel that displayed mechanical adaptability and shear resistance by UV-triggered photoreduction. 28 Their result show that the COF value decreased under the increasing loading conditions, but the anti-wearing property still was not mentioned here. There are challenges for high-strength hydrogels that resist loads while still maintaining low friction and wear resistance under high loads.…”

“…However, when the applied loads increased, the COF increased significantly. Yu et al developed a layered “CS-Fe” hydrogel that displayed mechanical adaptability and shear resistance by UV-triggered photoreduction . Their result show that the COF value decreased under the increasing loading conditions, but the anti-wearing property still was not mentioned here.…”

A pH-responsive metal-organic framework for the co-delivery of HIF-2α siRNA and curcumin for enhanced therapy of osteoarthritis

“…Though various biochemical factors contribute to the development of OA, its underlying mechanisms remain unclear [3][4][5]. Typically, this disease is characterized by a greatly reduced lubrication, causing cartilage damage and successive joint inflammations [6,7]. Specifically, the continuous inflammatory response and excessive matrix metalloproteinases (MMPs) stimulated by up-regulated inflammatory cytokines degrade the extracellular matrix (ECM) and reduce chondrocyte activity.…”