CD44 and inflammatory bowel disease: The second article, published in Biomaterials by Gou et al. (2019), is titled “Multi-bioresponsive Silk Fibroin-based Nanoparticles with On-demand Cytoplasmic Drug Release Capacity for CD44-Targeted Alleviation of Ulcerative Colitis.” These two original articles introduce the biocompatibility and targeted delivery ability of nanomaterials, demonstrating that nanomedicine can improve the therapeutic efficiency of IBD by maintaining gut microbiome homeostasis and regulating the innate immune response.