Excessive inflammation caused by bacterial infection is the primary cause of implant failure. Antibiotic treatment often fails to prevent peri-implant infection and may induce unexpected drug resistance. Herein, a non-antibiotic strategy based on the synergy of silver ion release and macrophage reprogramming is proposed for preventing infection and bacteria-induced inflammation suppression by the organic-inorganic hybridization of silver nanoparticle (AgNP) and quercetin (Que) into a polydopamine (PDA)-based coating on the 3D framework of porous titanium (SQPdFT). Once the planktonic bacteria (e.g., Escherichia coli, Staphylococcus aureus) reach the surface of SQPdFT, released Que disrupts the bacterial membrane. Then, AgNP can penetrate the invading bacterium and kill them, which further inhibits the biofilm formation. Simultaneously, released Que can regulate macrophage polarization homeostasis via the peroxisome proliferators-activated receptors gamma (PPARγ)-mediated nuclear factor kappa-B (NF-κB) pathway, thereby terminating excessive inflammatory responses. These advantages facilitate the adhesion and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs), concomitantly suppressing osteoclast maturation, and eventually conferring superior mechanical stability to SQPdFT within the medullary cavity. In summary, owing to its excellent antibacterial effect, immune remodeling function, and pro-osteointegration ability, SQPdFT is a promising protective coating for titanium-based implants used in orthopedic replacement surgery.
Current cancer immunotherapies exhibit low response rates attributed to suppressive tumor immune microenvironments (TIMEs). To address these unfavorable TIMEs, supplementation with tumor-associated antigens and stimulation of immune cells at target sites are indispensable for eliciting anti-tumoral immune responses. Previous research has explored the induction of immunotherapy through multiple injections and implants; however, these approaches lack consideration for patient convenience and the implementation of finely tunable immune response control systems to mitigate the side effects of over-inflammatory responses, such as cytokine storms. In this context, we describe a patient-centric nano-gel-nano system capable of sustained generation of tumor-associated antigens and release of adjuvants. This is achieved through the specific delivery of drugs to cancer cells and antigens/adjuvants to immune cells over the long term, maintaining proper concentrations within the tumor site with a single injection. This system demonstrates local immunity against tumors with a single injection, enhances the therapeutic efficacy of immune checkpoint blockades, and induces systemic and memory T cell responses, thus minimizing systemic side effects.