Burns are a common medical problem globally, and wound infection is one of the major causes of inducing related complications. Although antibiotics effectively prevent wound infections, the misuse of antibiotics has created a new problem of superbugs. Herein, we propose a new strategy to obtain pH-responsive antimicrobial P-ZIF (ZIF: zeolitic imidazolate framework) by loading polyhexamethylenebiguanide (PHMB) into the framework of ZIF-8 nanoparticles. This will enable PHMB to be released in the weak acid environment of an infected wound. To address burn infections, P-ZIF nanoparticles were loaded into a hydrogel system made of sodium alginate (SA) and 3-aminophenylboronic acid modified human-like collagen (H-A) through borate ester bonds. The resulting H-A/SA/P-ZIF (HASPZ) hydrogel dressing not only possesses antibacterial and wound healing properties but also has dual pH responsiveness to prevent the overuse of medication while effectively treat deep second-degree burns. Therefore, P-ZIF nanoparticles and the corresponding HASPZ hydrogel dressing are considered of significant importance in antimicrobial, drug delivery, and wound repair.

The therapy of bone defects based on advanced biological scaffolds offers the most promising therapeutic strategy for bone reconstruction. It is still challenging to develop scaffolds with the mechanical, osteogenic, angiogenic, and antibacterial properties required for bone defect reconstruction. Here, a novel organic/inorganic composite scaffold (zinc-whitlockite (ZnWH)/G/H) was synthesized using gellan gum (GG), human-like collagen (HLC), and ZnWH nanoparticles. The scaffold had excellent mechanical properties, adjustable swelling ratio, and interconnected pore structure. In addition to its excellent biocompatibility, it could promote osteogenic differentiation by releasing ZnWH nanoparticles to stimulate human bone marrow mesenchymal stem cells (hBMSCs) to upregulate the levels of alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In addition, this study showed that ZnWH nanoparticles could also promote angiogenesis by upregulating the paracrine secretion of vascular endothelial growth factor (VEGF) in hBMSCs. At the same time, the scaffold could inhibit the proliferation of bacteria. After 12 weeks of treatment in the rabbit femoral defect model, the ZnWH/G/H scaffold significantly accelerated the process of bone reconstruction. Therefore, these results demonstrate that the prepared novel nanocomposite scaffold, ZnWH/G/H, offers a promising candidate for bone regeneration.