A Bioinspired Strategy Toward UV Absorption Enhancement of Melaninlike Polymers for Sun Protection

Due to the complexity of the structure within melanin and synthetic polymers(i.e.,polydopamine,PDA),it is a challenge to regulate the ultraviolet(UV)absorption.In nature,melanocytes can biosynthesize more pheomelanins than eumelanins via protein and gene overexpression for photoprotection when the UV irradiation is enhanced.During this biosynthetic pathway,L-cystine,transported by xCT gene,can be involved to form a new monomer structure incorporating a benzothiazole group,finally resulting in the formation of UV absorption-enhanced pheomelanin.Inspired by this,we have proposed a facile strategy to regulate the UV absorption of PDA by introducing the benzimidazole(BI)unit through the thiol-Michael addition reaction during the polymerization process.It was further found that the introduction of BI units not only significantly increased the content of chromophores and auxochromes,but also effectively restricted the red-shift of the absorption spectrum via interrupting the conjugated microstructure within PDA,both of which contribute to UV absorption enhancement.These UV absorption-enhanced PDA nanoparticles could be used to fabricate bio-inspired sunscreens for efficient sun protection.This work will provide a facile strategy to regulate UV absorption of melanin-like materials and open new horizons for the design and construction of bioinspired sunscreens.

Carrier-Free Deferoxamine Nanoparticles against Iron Overload in Brain

Although considerable progress has been achieved in treating iron-overload diseases with deferoxamine(DFO)-based biomaterials,high DFO loading and multifunctional integration in one system are still grand challenges.Herein,a series of carrier-free,high DFO-loading(∼80%),uniform spherical nanoparticles(NPs)assisted by polyphenols have been facilely developed with both efficient iron and reactive oxygen species-scavenging properties.Interestingly,those DFO-based NPs have demonstrated excellent scavenging performance in iron-overloaded cell model and energetically exhibited brain cell protection in vivo in intracerebral hemorrhage animal models.This study could provide a promising strategy to significantly improve the curative effect of DFO delivery systems for iron-overload diseases.

Superabsorbent poly(acrylic acid) and antioxidant poly(ester amide) hybrid hydrogel for enhanced wound healing

Wound healing dressing is increasingly needed in clinical owing to the large quantity of skin damage annually.Excessive reactive oxygen species(ROS)produced through internal or external environmental influences can lead to lipid peroxidation,protein denaturation,and even DNA damage,and ultimately have harmful effects on cells.Aiming to sufficiently contact with the wound microenvironment and scavenge ROS,superabsorbent poly(acrylic acid)and antioxidant poly(ester amide)(PAA/PEA)hybrid hydrogel has been developed to enhance wound healing.The physical and chemical properties of hybrid hydrogels were studied by Fourier-transform infrared(FTIR)absorption spectrum,compression,swelling,degradation,etc.Besides,the antioxidant properties of hybrid hydrogels can be investigated through the free radical scavenging experiment,and corresponding antioxidant indicators have been tested at the cellular level.Hybrid hydrogel scaffolds supported the proliferation of human umbilical vein endothelial cells and fibroblasts,as well as accelerated angiogenesis and skin regeneration in wounds.The healing properties of wounds in vivo were further assessed on mouse skin wounds.Results showed that PAA/PEA hybrid hydrogel scaffolds significantly accelerated the wound healing process through enhancing granulation formation and re-epithelialization.In summary,these superabsorbent and antioxidative hybrid hydrogels could be served as an excellent wound dressing for full-thickness wound healing.

Propolis inspired sunscreens for efficient UV-protection and skin barrier maintenance

The direct use of naturally occurring,small molecular ingredients in bioinspired sunscreens has raised several concerns due to the instability,photocytotoxicity,and potential blood toxicity of those ingredients.In this work,we have employed natural ultraviolet(UV)-blocking molecule caffeic acid phenethyl ester(CAPE)from propolis to prepare poly(CAPE)nanoparticles(NPs)as the main bioactive ingredient to fabricate propolis-inspired hydrogel sunscreens.Compared with small molecular CAPE,poly(CAPE)NPs exhibited better dispersion and stability in water,as well as lower physiological toxicity and skin permeability.And the resulting composite hydrogels demonstrated promising properties including water-resistant whereas can be easily erased by warm water as well as safety when interacting with skin.More importantly,the hydrogel sunscreens showed excellent UV protection properties both in vitro and in vivo,and the positive effects in maintaining skin barrier functions.This work provides new strategies towards the facile construction of nature-inspired robust sunscreens in the future.