Visible light crosslinkable human hair keratin hydrogels

Abstract

Keratins extracted from human hair have emerged as a promising biomaterial for various biomedical applications, partly due to their wide availability, low cost, minimal immune response, and the potential to engineer autologous tissue constructs. However, the fabrication of keratin‐based scaffolds typically relies on limited crosslinking mechanisms, such as via physical interactions or disulfide bond formation, which are time‐consuming and result in relatively poor mechanical strength and stability. Here, we report the preparation of photocrosslinkable keratin‐polyethylene glycol (PEG) hydrogels via the thiol‐norbornene “click” reaction, which can be formed within one minute upon irradiation of visible light. The resulting keratin‐PEG hydrogels showed highly tunable mechanical properties of up to 45 kPa in compressive modulus, and long‐term stability in buffer solutions and cell culture media. These keratin‐based hydrogels were tested as cell culture substrates in both two‐dimensional surface seeding and three‐dimensional cell encapsulation, demonstrating excellent cytocompatibility to support the attachment, spreading, and proliferation of fibroblast cells. Moreover, the photocrosslinking mechanism makes keratin‐based hydrogel suitable for various microfabrication techniques, such as micropatterning and wet spinning, to fabricate cell‐laden tissue constructs with different architectures. We believe that the unique features of this photocrosslinkable human hair keratin hydrogel promise new opportunities for their future biomedical applications.

Hydrogels in the clinic

“…Due to this high water content, hydrogels exhibit favorable biocompatibility and as such have been developed for and used in a variety of medical applications 1‐3 . Since hydrogel properties can be tuned through a variety of chemical approaches, their rational design and engineering has enabled new modalities for delivery of small molecules, 4‐7 proteins, 8‐12 and cells 13,14 and as tissue engineering scaffolds for directing cell fate/lineage, 15,16 stem cell expansion, 17‐20 and tissue regeneration 21‐25 . Research efforts to develop hydrogels for biomedical applications represents one of the most studied areas at the interface of engineering and medicine 26 .…”

Advances in osteobiologic materials for bone substitutes

“…By adding cells into a hydrogel precursor prior to gelling process, cells can be distributed homogeneously within the hydrogel scaffold. In general, hydrogels from natural sources are derived from polymers such as collagen, gelatin, keratin, hyaluronic acid, fibrin, alginate, agarose, chitosan, or synthetic hydrogels such as Poloxamer 4007, polyethylene glycol, or combination of natural and synthetic hydrogels such as gelatin methacrylate (Drury & Mooney, ; Yue et al, ).…”

Metal‐Free and Heterogeneous Photocatalytic Reduction of 4‐Nitroaniline by a Poly(Ethylene Glycol)‐Supported Eosin Dye under Visible‐Light Exposure

“…The reaction is done under visible‐light irradiation, at room temperature, by employing a photocrosslinked PEG‐based photocatalyst support containing eosin Y. The advantages of our process are: 1) the rapidity of synthesis of the photocatalytic support, 2) the use of a non‐toxic poly(ethylene glycol) diacrylate (DAPEG) matrix 3) the application of eosin Y, approved by Food and Drug Administration, which does not reveal any toxicological or environmental problems, and can be used as an efficient photocatalyst and 4) eosin Y is not released from the PEG‐based photocatalyst support due to the highly cross‐linked polymer matrix. To the best of our knowledge, such a combination between eosin Y and PEG‐based photocatalyst support without any metal catalyst, has never been reported in the literature for the heterogeneous photocatalytic reductions of 4‐nitroaniline.…”