Bacterial biofilm‐associated infections (BAIs) are the leading cause of prosthetic implant failure. The dense biofilm structure prevents antibiotic penetration, while the highly acidic and H2O2‐rich biofilm microenvironment (BME) dampens the immunological response of antimicrobial macrophages. Conventional treatments that fail to consistently suppress escaping planktonic bacteria from biofilm result in refractory recolonization, allowing BAIs to persist. Herein, a BME‐responsive copper‐doped polyoxometalate clusters (Cu‐POM) combination with mild photothermal therapy (PTT) and macrophage immune re‐rousing for BAI eradication at all stages is proposed. The self‐assembly of Cu‐POM in BME converts endogenous H2O2 to toxic ·OH through chemodynamic therapy (CDT) and generates a mild PTT effect to induce bacterial metabolic exuberance, resulting in loosening the membrane structure of the bacteria, enhancing copper transporter activity and increasing intracellular Cu‐POM flux. Metabolomics reveals that intracellular Cu‐POM overload restricts the TCA cycle and peroxide accumulation, promoting bacterial cuproptosis‐like death. CDT re‐rousing macrophages scavenge planktonic bacteria escaping biofilm disintegration through enhanced chemotaxis and phagocytosis. Overall, BME‐responsive Cu‐POM promotes bacterial cuproptosis‐like death via metabolic interference, while also re‐rousing macrophage immune response for further planktonic bacteria elimination, resulting in all‐stage BAI clearance and providing a new reference for future clinical application.

Biofilms are colonies of bacteria embedded inside a complicated self-generating intercellular. The formation and scatter of a biofilm is an extremely complex and progressive process in constant cycles. Once formed, it can protect the inside bacteria to exist and reproduce under hostile conditions by establishing tolerance and resistance to antibiotics as well as immunological responses. In this article, we reviewed a series of innovative studies focused on inhibiting the development of biofilm and summarized a range of corresponding therapeutic methods for biological evolving stages of biofilm. Traditionally, there are four stages in the biofilm formation, while we systematize the therapeutic strategies into three main periods precisely:(i) period of preventing biofilm formation: interfering the colony effect, mass transport, chemical bonds and signaling pathway of plankton in the initial adhesion stage; (ii) period of curbing biofilm formation:targeting several pivotal molecules, for instance, polysaccharides, proteins, and extracellular DNA (eDNA) via polysaccharide hydrolases, proteases, and DNases respectively in the second stage before developing into irreversible biofilm; (iii) period of eliminating biofilm formation: applying novel multifunctional composite drugs or nanoparticle materials cooperated with ultrasonic (US), photodynamic, photothermal and even immune therapy, such as adaptive immune activated by stimulated dendritic cells (DCs), neutrophils and even immunological memory aroused by plasmocytes. The multitargeted or combinational therapies aim to prevent it from developing to the stage of maturation and dispersion and eliminate biofilms and planktonic bacteria simultaneously.

The recurrence of biofilm‐associated infections (BAIs) remains high after implant‐associated surgery. Biofilms on the implant surface reportedly shelter bacteria from antibiotics and evade innate immune defenses. Moreover, little is currently known about eliminating residual bacteria that can induce biofilm reinfection. Herein, novel “interference‐regulation strategy” based on bovine serum albumin–iridium oxide nanoparticles (BIONPs) as biofilm homeostasis interrupter and immunomodulator via singlet oxygen (1O2)‐sensitized mild hyperthermia for combating BAIs is reported. The catalase‐like BIONPs convert abundant H2O2 inside the biofilm‐microenvironment (BME) to sufficient oxygen gas (O2), which can efficiently enhance the generation of 1O2 under near‐infrared irradiation. The 1O2‐induced biofilm homeostasis disturbance (e.g., sigB, groEL, agr‐A, icaD, eDNA) can disrupt the sophisticated defense system of biofilm, further enhancing the sensitivity of biofilms to mild hyperthermia. Moreover, the mild hyperthermia‐induced bacterial membrane disintegration results in protein leakage and 1O2 penetration to kill bacteria inside the biofilm. Subsequently, BIONPs‐induced immunosuppressive microenvironment re‐rousing successfully re‐polarizes macrophages to pro‐inflammatory M1 phenotype in vivo to devour residual biofilm and prevent biofilm reconstruction. Collectively, this 1O2‐sensitized mild hyperthermia can yield great refractory BAIs treatment via biofilm homeostasis interference, mild‐hyperthermia, and immunotherapy, providing a novel and effective anti‐biofilm strategy.

Over the past decade, a proliferation of research has used nanoparticles to deliver gaseous signaling molecules for medical purposes. The discovery and revelation of the role of gaseous signaling molecules have been accompanied by nanoparticle therapies for their local delivery. While most of them have been applied in oncology, recent advances have demonstrated their considerable potential in diagnosing and treating orthopedic diseases. Three of the currently recognized gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are highlighted in this review along with their distinctive biological functions and roles in orthopedic diseases. Moreover, this review summarizes the progress in therapeutic development over the past ten years with a deeper discussion of unresolved issues and potential clinical applications.