Cu–Fe bimetallic nanozyme@halloysite–sodium alginate composite hydrogels for the treatment of atopic dermatitis

Atopic dermatitis is a typical chronic inflammatory disease with pathological characteristics of persistent immune activation and oxidative stress. Combined anti-inflammatory and antioxidant treatment can effectively block the inflammatory cascade while reducing oxidative damage. Halloysite nanotubes (HNTs) are the main components of the traditional Chinese medicine "Chishizhi", which shows the medicinal functions of hemostasis and astringency. However, the efficacy of HNTs alone in treating diseases is relatively weak, and their therapeutic effect can be improved by surface modification and drug loading. Herein, CuO-Fe₃O₄ nanoparticles were synthesized on the outer surfaces of HNTs by a hydrothermal reaction. CuO-Fe₃O₄@HNTs have high SOD and CAT enzyme activities under neutral conditions. Then, the nanozyme-modified HNT powder was prepared into sprayable hydrogels by introduction of sodium alginate (SA) and aloe vera extracts. Cell experiments confirmed that the hydrogel can promote HacaT cell proliferation within 0-200 μg mL^-1 concentration. Through the mouse dermatitis model, it was seen that a CuO-Fe₃O₄@HNTs-SA composite hydrogel has a good therapeutic effect on atopic dermatitis. Compared with the positive drug halcinonide solution, the CuO-Fe₃O₄ nanozyme-incorporated hydrogel showed an enhanced therapeutic effect, which shows promising prospects for the clinical treatment of atopic dermatitis.