Dissolution of copper mineral phases in biological fluids and the controlled release of copper ions from mineralized alginate hydrogels

Cupric-polymeric nanoreactors integrate into copper metabolism to promote chronic diabetic wounds healing

Given multifunction of copper (Cu) contributing to all stages of the physiology of wound healing, Cu-based compounds have great therapeutic potentials to accelerate the wound healing, but they must be limited to a very low concentration range to avoid detrimental accumulation. Additionally, the cellular mechanism of Cu-based compounds participating the healing process remains elusive. In this study, copper oxide nanoparticles (CuONPs) were synthesized to mimic the multiple natural enzymes and trapped into PEG-b-PCL polymersomes (PS) to construct cupric-polymeric nanoreactors (CuO@PS) via a direct hydration method, thus allowing to compartmentalize Cu-based catalytic reactions in an isolated space to improve the efficiency, selectivity, recyclability as well as biocompatibility. While nanoreactors trafficked to lysosomes following endocytosis, the released Cu-based compounds in lysosomal lumen drove a cytosolic Cu+ influx to mobilize Cu metabolism mostly via Atox1-ATP7a/b-Lox axis, thereby activating the phosphorylation of mitogen-activated protein kinase 1 and 2 (MEK1/2) to initiate downstream signaling events associated with cell proliferation, migration and angiogenesis. Moreover, to facilitate to lay on wounds, cupric-polymeric nanoreactors were finely dispersed into a thermosensitive Pluronic F127 hydrogel to form a composite hydrogel sheet that promoted the healing of chronic wounds in diabetic rat models. Hence, cupric-polymeric nanoreactors represented an attractive translational strategy to harness cellular Cu metabolism for chronic wounds healing.

Advances in Copper-Based Biomaterials With Antibacterial and Osteogenic Properties for Bone Tissue Engineering

Treating bone defects coupled with pathogen infections poses a formidable challenge to clinical medicine. Thus, there is an urgent need to develop orthopedic implants that provide excellent antibacterial and osteogenic properties. Of the various types, copper-based biomaterials capable of both regenerating bone and fighting infections are an effective therapeutic strategy for bone tissue engineering and therefore have attracted significant research interest. This review examines the advantages of copper-based biomaterials for biological functions and introduces these materials’ antibacterial mechanisms. We summarize current knowledge about the application of copper-based biomaterials with antimicrobial and osteogenic properties in the prevention and treatment of bone infection and discuss their potential uses in the field of orthopedics. By examining both broad and in-depth research, this review functions as a practical guide to developing copper-based biomaterials and offers directions for possible future work.

Metal alginates for polyphenol delivery systems: Studies on crosslinking ions and easy-to-use patches for release of protective flavonoids in skin

Incorporation of bioactive natural compounds like polyphenols is an attractive approach for enhanced functionalities of biomaterials. In particular flavonoids have important pharmacological activities, and controlled release systems may be instrumental to realize the full potential of these phytochemicals. Alginate presents interesting attributes for dermal and other biomaterial applications, and studies were carried here to support the development of polyphenol-loaded alginate systems. Studies of capillary viscosity indicated that ionic medium is an effective strategy to modulate the polyelectrolyte effect and viscosity properties of alginates. On gelation, considerable differences were observed between alginate gels produced with Ca2+, Ba2+, Cu2+, Fe2+, Fe3+ and Zn2+ as crosslinkers, especially concerning shrinkage and morphological regularity. Stability assays with different polyphenols in the presence of alginate-gelling cations pointed to the choice of calcium, barium and zinc as safer crosslinkers. Alginate-based films loaded with epicatechin were prepared and the kinetics of release of the flavonoid investigated. The results with calcium, barium and zinc alginate matrices indicated that the release dynamics is dependent on film thicknesses, but also on the crosslinking metal used. On these grounds, an alginate-based system of convenient use was devised, so that flavonoids can be easily loaded at simple point-of-care conditions before dermal application. This epicatechin-loaded patch was tested on an ex-vivo skin model and demonstrated capacity to deliver therapeutically relevant concentrations on skin surface. Moreover, the flavonoid released was not modified and retained full antioxidant bioactivity. The alginate-based system proposed offers a multifunctional approach for flavonoid controllable delivery and protection of skin injured or under risk.