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Collagen has shown promising potential in biomedical fields due to its high biocompatibility, abundance of resources, ease of flexible modification, and potential for active targeting. The biomedical capacity is largely influenced by their unique structure and properties. Collagen is typically extracted from tissues and organs that are commonly discarded as waste. The extraction of collagen from agricultural and sideline resources is an environmentally friendly method for utilizing byproducts and generating high-value products. The extraction methods can significantly impact the structure and composition. Collagens can be cross-linked using external reagents or techniques to enhance their strength and meet growing demands. This review will discuss the recent advancements in collagen-based biomaterials for chronic wound healing, bone regeneration, and cornea defect repair, focusing on extraction and modification strategies. We are dedicated to bridging the gap between the pretreatment of collagens in various processes and their specific applications. This will facilitate the scientific design and optimal utilization of collagen-based biomaterials for tissue regeneration. This review provides readers with a comprehensive understanding of the advancements in extraction methods, cross-linking strategies, and the biomedical applications of collagen. [ABSTRACT FROM AUTHOR]

A retro-aldol reaction of two β-hydroxy compounds in synergy with Pd-catalyzed cross-coupling of aryl halides is reported herein, which produces selectively mono-α-arylated ketones and esters in good yields. This reaction is compatible with a broad range of aryl iodides, bromides, chlorides, and triflates and can tolerate an array of functional groups on the aromatic ring. Ready scale-up of this reaction to gram level is applicable without an appreciable decrease in the reaction yield. Furthermore, concise syntheses of biologically active isocoumarin and indole derivatives have been achieved to greatly demonstrate the synthetic value of this retro-aldol reaction. Finally, the reaction mechanism has been discussed on the basis of experimental observations and DFT computational results. A regulated six-membered-ring transition structure has been located for the key retro-aldol C−C cleavage, which constitutes the rate-determining step of a full catalytic cycle. The concept of C−C activation by retro-aldol reaction may also find applications in other fundamental reactions.