Modifying surface resistivity and liquid moisture management property of keratin fibers through thiol-ene click reactions

Current Understanding of the Applications of Photocrosslinked Hydrogels in Biomedical Engineering

Hydrogel materials have great application value in biomedical engineering. Among them, photocrosslinked hydrogels have attracted much attention due to their variety and simple convenient preparation methods. Here, we provide a systematic review of the biomedical-engineering applications of photocrosslinked hydrogels. First, we introduce the types of photocrosslinked hydrogel monomers, and the methods for preparation of photocrosslinked hydrogels with different morphologies are summarized. Subsequently, various biomedical applications of photocrosslinked hydrogels are reviewed. Finally, some shortcomings and development directions for photocrosslinked hydrogels are considered and proposed. This paper is designed to give researchers in related fields a systematic understanding of photocrosslinked hydrogels and provide inspiration to seek new development directions for studies of photocrosslinked hydrogels or related materials.

Polycaprolactone strengthening keratin/bioactive glass composite scaffolds with double cross-linking networks for potential application in bone repair

In this study, we aimed at constructing polycaprolactone (PCL) reinforced keratin/bioactive glass composite scaffolds with a double cross-linking network structure for potential bone repair application. Thus, the PCL-keratin-BG composite scaffold was prepared by using keratin extracted from wool as main organic component and bioactive glass (BG) as main inorganic component, through both cross-linking systems, such as the thiol-ene click reaction between abundant sulfhydryl groups of keratin and the unsaturated double bond of 3-methacryloxy propyltrimethoxy silane (MPTS), and the amino-epoxy reaction between amino groups of keratin and the epoxy group in (3-glycidoxymethyl) methyldiethoxysilane (GPTMS) molecule, along with introduction of PCL as a reinforcing agent. The success of the thiol-ene reaction was verified by the FTIR and 1H-NMR analyses. And the structure of keratin-BG and PCL-keratin-BG composite scaffolds were studied and compared by the FTIR and XRD characterization, which indicated the successful preparation of the PCL-keratin-BG composite scaffold. In addition, the SEM observation, and contact angle and water absorption rate measurements demonstrated that the PCL-keratin-BG composite scaffold has interconnected porous structure, appropriate pore size and good hydrophilicity, which is helpful to cell adhesion, differentiation and proliferation. Importantly, compression experiments showed that, when compared with the keratin-BG composite scaffold, the PCL-keratin-BG composite scaffold increased greatly from 0.91 ± 0.06 MPa and 7.25 ± 1.7 MPa to 1.58 ± 0.21 MPa and 14.14 ± 1.95 MPa, respectively, which suggesting the strong reinforcement of polycaprolactone. In addition, the biomineralization experiment and MTT assay indicated that the PCL-keratin-BG scaffold has good mineralization ability and no-cytotoxicity, which can promote cell adhesion, proliferation and growth. Therefore, the results suggested that the PCL-keratin-BG composite scaffold has the potential as a candidate for application in bone regeneration field.

Graphical Abstract

Thiol-ene photoclick reaction: An eco-friendly and facile approach for preparation of MPEG-g-keratin biomaterial

Wool keratin is a natural material with excellent properties, which is considered as scaffold biomaterial for tissue engineering. Polyethylene glycol can improve the mechanical properties of keratin materials because of its excellent biocompatibility and plasticity. In the present work, poly (ethylene glycol) methyl ether methacrylate (MPEGMA) was grafted onto keratin by thiol-ene photoclick reaction. The results of FTIR and SDS-PAGE verified the successful reaction between MPEGMA and keratin. Compared with the keratin, circular dichroism and XRD results showed that the β-sheet ratio increased in MPEG-g-keratin. Additionally, it can be found that the exposure of keratin hydrophobic amino acids increased quickly and the micelle size became larger due to the introduction of MPEG from the results of fluorescence spectroscopy and particle size analysis. The MPEG-g- keratin was formed into a membrane to further study the application of the modified keratin. Compared with the keratin membrane, the flexibility and biocompatibility of modified keratin have been improved. This work provides an eco-friendly and facile approach for preparation of the keratin biomaterials.

Atomic layer deposition of Co3O4 nanocrystals on N-doped electrospun carbon nanofibers for oxygen reduction and oxygen evolution reactions

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are considered as the two crucial reactions in key renewable-energy technologies including fuel cells and water splitting. Despite promising research progress in the preparation of various non-noble metal based electrocatalysts, it is still highly challenging but desirable to develop novel fabrication strategies to synthesize highly active and cost-effective ORR/OER bifunctional electrocatalysts in a precisely controlled manner. Herein, we report atomic layer deposition (ALD) of highly monodisperse Co3O4 nanocrystals of different sizes on N-doped electrospun carbon nanofibers (nCNFs) as high performance bifunctional catalysts (Co@nCNFs) for the ORR and OER. Co@nCNFs (with an average Co3O4 particle size of ∼3 nm) show high ORR performance exhibiting an onset potential of 0.87 V with a low Tafel slope of 119 mV dec-1 approaching that of commercial Pt/C. Similarly, the Co@nCNF electrocatalyst showed remarkable catalytic activity in the OER. The turnover frequency (TOF) value determined at an overpotential of 550 mV for the Co@nCNFs is ∼0.14 s-1 which is ca. 3 and ca. 15-fold higher than those of bulk Co (∼0.05 s-1) and the standard state-of-the-art IrO x (0.0089 s-1) catalyst, respectively. This work will open new possibilities for fabrication of inexpensive non-noble metal materials in highly controlled manner for applications as bifunctional ORR/OER electrocatalysis.

An ionic liquid functionalized graphene adsorbent with multiple adsorption mechanisms for pipette-tip solid-phase extraction of auxins in soybean sprouts

A new ionic liquid functionalized graphene-pipette-tip solid-phase extraction method coupled with high-performance liquid chromatography was established for the simultaneous extraction and determination of three auxins in soybean sprouts. The graphene adsorbent, with multiple adsorption mechanisms, was first synthesized by functional modification of pentafluorobenzyl imidazolium bromide ionic liquid through thiol-ene click chemistry. The ionic liquid was applied to prevent the aggregation of graphene; it also imbued graphene with the ability for π-π interactions, ionic exchange, electrostatic interactions, as well as hydrogen bonding (which is stronger than the interaction between water and analytes), by augmenting the adsorption mechanisms between the adsorbent and analytes. Under optimized conditions, linearity was achieved in the ranges 0.03-5.00 µg/g for indole-3-acetic acid and 1-naphthaleneacetic acid and 0.09-5.00 µg/g for 2,4-dichlorophenoxyacetic acid, with a detection limit of 0.004-0.026 µg/g; this adsorbent has been successfully applied for the determination of auxins in soybean sprouts.

Multi-functional wool fabrics by graft-copolymerisation with polystyrene sulphonate: their enhanced fire retardancy, mechanical properties, and stain-resistance

pSS-Grafted wool fabrics showed enhanced fire retardancy, tensile strength and stain-resistance against an acid dye-based stain.

Visible light crosslinkable human hair keratin hydrogels

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.

Durable antibacterial finishing of cotton fabric based on thiol–epoxy click chemistry

This research proposes a method based on thiol–epoxy click chemistry to achieve durable antibacterial properties on cotton fabrics.

Preparation of a reactive flame retardant and its finishing on cotton fabrics based on click chemistry

The non-halogenated organophosphorus flame retardant dimethyl-[1,3,5-(3,5-triacryloylhexahydro)triazinyl]-3-oxopropylphosphonate (DHTP) was synthesized and immobilized on cotton fabrics for a flame retardant finishing using click chemistry.

Preparation of antibacterial keratin fabrics via UV curing and click chemistry

A clean and cost-effective surface modification method of keratin fabrics was proposed by UV curing and thiolene click reaction.

Synthesis of a gemini quaternary ammonium salt and its reaction with wool fabric using click chemistry

In this study, we have successfully synthesized a gemini quaternary ammonium salt C₂₄H₃₈O₄N₂Br₂ and applied it to wool fabric to obtain antibacterial properties.