In situ hydrogels have attracted considerable attention in tissue engineering because of their minimal invasiveness and ability to match the irregular tissue defects. However, hydrous physiological environments and the high level of moisture in hydrogels severely hamper binding to the target tissue and easily cause wound infection, thereby limiting the effectiveness in wound care management. Thus, forming an intimate assembly of the hydrogel to the tissue and preventing wound infecting still remains a significant challenge. In this study, inspired by mussel adhesive protein, a biomimetic dopamine‐modified ε‐poly‐l‐lysine‐polyethylene glycol‐based hydrogel (PPD hydrogel) wound dressing is developed in situ using horseradish peroxidase cross‐linking. The biomimetic catechol–Lys residue distribution in PPD polymer provides a catechol–Lys cooperation effect, which endows the PPD hydrogels with superior wet tissue adhesion properties. It is demonstrated that the PPD hydrogel can facilely and intimately integrate with biological tissue and exhibits superior capacity of in vivo hemostatic and accelerated wound repair. In addition, the hydrogels exhibit outstanding anti‐infection property because of the inherent antibacterial ability of ε‐poly‐l‐lysine. These findings shed new light on the development of mussel‐inspired tissue‐anchored and antibacterial hydrogel materials serving as wound dressings.
Novel
sunscreen products based on bioadhesive/gel systems that
can prevent the skin penetration behaviors of UV filters have attracted
increasing attention in recent years. However, integration is very
difficult to achieve and control on the wet surface of the skin under
sweaty/dynamic physiological conditions, resulting in functional failure.
Herein, we demonstrated the fabrication of a novel dual-network hydrogel
sunscreen (DNHS) based on poly-γ-glutamic acid (γ-PGA)
and tannic acid (TA), which demonstrated prominent UV protection properties
across broad UVA and UVB regions (360–275 nm). Due to a three-dimensional
network microstructure and a highly hydrated nature that mimics the
extracellular matrix of natural skin, DNHS can perfectly match the
skin surface without irritation and sensitization. In addition, the
intermolecular hydrogen bond interactions of γ-PGA and TA provide
an important driving force for coacervation, which endows the DNHS
with remarkable self-recovery properties (within 60 s). Moreover,
due to the multiple interfacial interactions between γ-PGA/TA
and the protein-rich skin tissue surfaces, DNHS simultaneously possesses
excellent skin-integration and water-resistance capacities, and it
can be readily removed on demand. Our results highlight the potential
of the DNHS to be used in next-generation sunscreens by providing
long-term and stable UV protection functions even under sweaty/dynamic
physiological conditions.
An enzyme-induced strategy is reported to construct novel self-mending hydrogels based on ε-poly-l-lysine with both excellent self-healing properties (95%) and antibacterial capacity. Most importantly, the hydrogels are able to accelerate wound healing efficiently, which shows great potential in myriad biomedical fields, such as wound repair, artificial skin, and tissue engineering.
Under photoredox catalysis conditions,
the conventional electrophilic
reactivity of ketimines is inverted to generate nucleophilic species.
As a result, chemoselective cross-electrophile couplings between aldehydes
and ketimines are achieved via umpolung reactivity of ketimines to
furnish amino alcohols (44 examples with good to excellent yields).
To illustrate the utility of the amino alcohol products, 1,2-dihydroindol-3-one-based
fluorophores are easily synthesized using the coupling products. Finally,
a plausible reaction pathway is discussed.
In this study, novel bio-inspired in situ hydrogels as tissue adhesives and hemostatic materials were designed and prepared based on ɛ-polylysine-grafted poly(ethylene glycol) and tyramine via enzymatic cross-linking. The enzymatic cross-linked method enabled fast gelation within seconds, which facilitated its therapeutic applications. By changing the cross-linking conditions, the storage modulus of the hydrogels could be tunable and the mechanical strength influenced the tissue adhesiveness of the hydrogels. Besides, the hydrogels showed fine network structures with appropriate pore sizes, which were thought to be a contributing factor to the strong adhesiveness. Benefiting from the strong mechanical properties and fine network structures, the ɛ-polylysine-grafted poly(ethylene glycol) and tyramine hydrogels exhibited superior wound-healing and hemostatic ability compared to conventional and commercially available medical materials. Moreover, indirect cytotoxicity assessment indicated that the ɛ-polylysine-grafted poly(ethylene glycol) and tyramine hydrogels were nontoxic to the L929 cell. These results demonstrated that the enzymatic cross-linked in situ ɛ-polylysine hydrogels hold high potential for tissue sealants and hemostatic materials.
Despite the vast variety of colloidal superstructures available in soft matter photonics, it remains challenging to balance the trade‐off between their optical microstructures and material processability. By synergizing colloidal photonics and dynamic chemistry, a type of photonic “plasticine” with characteristics of uniform structural colors, high processability, and self‐healing is demonstrated. Specifically, a boronate ester bond‐based macromonomer is first prepared through complexation between the diols of polyvinyl alcohol and the boronic acid group of 3‐(acrylamido) phenylboronic acid in the presence of concentrated silica colloids. Upon photopolymerization, the dynamic photonic plasticine is formed in situ as the result of the crosslinking of the boronate ester bonded networks. The randomly packed colloids inside the plasticine compose the amorphous photonic crystals, giving rise to angle‐independent structural colors that would not compromise during subsequent processing steps; the reversible nature of the boronate ester bonds endows the plasticine with self‐adaptable and self‐healing properties. Further, the plasticine is also compatible with common shaping methods, that is, cutting, molding, and carving, and thus can be facilely processed into 3D structural colored objects, holding great potentials in fields such as bio‐encoding, optical filters, anti‐counterfeiting, etc.
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