Soft tissue losses from tumor removal, trauma, aging, and congenital malformation affect millions of people each year. Existing options for soft tissue restoration have several drawbacks: Surgical options such as the use of autologous tissue flaps lead to donor site defects, prosthetic implants are prone to foreign body response leading to fibrosis, and fat grafting and dermal fillers are limited to small-volume defects and only provide transient volume restoration. In addition, large-volume fat grafting and other tissue-engineering attempts are hampered by poor vascular ingrowth. Currently, there are no off-the-shelf materials that can fill the volume lost in soft tissue defects while promoting early angiogenesis. Here, we report a nanofiber-hydrogel composite that addresses these issues. By incorporating interfacial bonding between electrospun poly(ε-caprolactone) fibers and a hyaluronic acid hydrogel network, we generated a composite that mimics the microarchitecture and mechanical properties of soft tissue extracellular matrix. Upon subcutaneous injection in a rat model, this composite permitted infiltration of host macrophages and conditioned them into the pro-regenerative phenotype. By secreting pro-angiogenic cytokines and growth factors, these polarized macrophages enabled gradual remodeling and replacement of the composite with vascularized soft tissue. Such host cell infiltration and angiogenesis were also observed in a rabbit model for repairing a soft tissue defect filled with the composite. This injectable nanofiber-hydrogel composite augments native tissue regenerative responses, thus enabling durable soft tissue restoration outcomes.

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Cadmium (Cd) isotopes have great potential for understanding Cd geochemical cycling in soil and aquatic systems. Iron (oxyhydr)­oxides can sequester Cd via adsorption and isomorphous substitution, but how these interactions affect Cd isotope fractionation remains unknown. Here, we show that adsorption preferentially enriches lighter Cd isotopes on iron (oxyhydr)­oxide surfaces through equilibrium fractionation, with a similar fractionation magnitude (Δ114/110Cdsolid‑solution) for goethite (Goe) (−0.51 ± 0.04‰), hematite (Hem) (−0.54 ± 0.10‰), and ferrihydrite (Fh) (−0.55 ± 0.03‰). Neither the initial Cd2+ concentration or ionic strength nor the pH influence the fractionation magnitude. The enrichment of the light isotope is attributed to the adsorption of highly distorted [CdO6] on solids, as indicated by Cd K-edge extended X-ray absorption fine-structure analysis. In contrast, Cd incorporation into Goe by substitution for lattice Fe at a Cd/Fe molar ratio of 0.05 preferentially sequesters heavy Cd isotopes, with a Δ114/110Cdsolid‑solution of 0.22 ± 0.01‰. The fractionation probably occurs during the transformation of Fh into Goe via dissolution and reprecipitation. These results improve the understanding of the Cd isotope fractionation behavior being affected by iron (oxyhydr)­oxides in Earth’s critical zone and demonstrate that interactions with minerals can obscure anthropogenic and natural Cd isotope characteristics, which should be carefully considered when applying Cd isotopes as environmental tracers.

Background One‐stage reconstruction of complex soft tissue defects of the extremities is a challenging problem. Repair of complex soft tissue defects requires adequate skin tissues to cover the large surface wound and special tissues for obliterating the dead space. The chimeric flap is one of the most popular approaches for reconstruction of complex soft tissue defects. However, the problems of donor‐site morbidity and inability to repair very large defects at one‐stage remain. The purpose of this study was to present our clinical experience using sequential chimeric perforator flaps for reconstruction of complex extremity defects with primary closure of the donor site. Methods From August 2013 to March 2017, 12 patients with complex soft tissue defects underwent extremity reconstruction using sequential chimeric perforator flaps, which were composed of a chimeric anterolateral thigh perforator (ALTP) flap and an additional free perforator flap. The skin paddles were placed side‐by‐side to cover the large surface soft tissue defects, and the muscle component was used to obliterate the dead space. Of these patients, one was injured by a crushing accident, while the other 11 patients were injured in traffic accidents. Results The size of the skin paddles ranged from 26 cm × 8 cm–10 cm × 6 cm to 30 cm × 8.5 cm–29 cm × 9 cm. The muscle paddle size ranged from 2 cm × 3 cm × 4 cm to 22 cm × 4 cm × 2 cm. All‐components of the sequential chimeric flaps survived in all‐patients. Vascular compromise was observed in one case. One case suffered minor wound‐edge necrosis and was treated conservatively. Primary closure of donor‐site was successfully achieved in all‐patients, and all‐donor‐site wounds healed uneventfully. The mean follow‐up time was 15.25 months. Most of the cases showed a satisfactory contour, and only two patients presented with mildly bulky appearance that treated with a debulking procedure. Conclusions The sequential chimeric perforator flap is an alternative procedure for reconstruct complex soft tissue defects of the extremities. This approach allows for flexible design, a larger cutaneous area, and low donor site morbidity.