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Because of the abuse of antibiotics and threats of antibiotic resistance, bacterial infection is still one of the most difficult issues to be resolved. Thus, it is of great significance to explore novel antibacterial agents. In this paper, we investigated a type of silica-coated gold–silver nanocages (Au–Ag@SiO2 NCs) as antibacterial candidates. Their intrinsic characteristics of photothermal property and sustained release of Ag ions were fully exploited for near-infrared (NIR)-induced combined anti-infective therapy. The broad-spectrum antibacterial property of the as-prepared Au–Ag@SiO2 NCs was confirmed in vitro against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). In addition, Au–Ag@SiO2 NCs exhibit effective treatment of the S. aureus biofilm with the assistance of NIR irradiation. More importantly, we assessed the in vivo antibacterial efficacy of Au–Ag@SiO2 NCs against S. aureus, which demonstrated sustainably enhanced therapeutic effects on a rat model with wound infection.

Responsive multifunctional organic/inorganic nanohybrids are promising for effective and precise imaging-guided therapy of cancer. In this work, a near-infrared (NIR)-triggered multifunctional nanoplatform comprising Au nanorods (Au NRs), mesoporous silica, quantum dots (QDs), and two-armed ethanolamine-modified poly(glycidyl methacrylate) with cyclodextrin cores (denoted as CD-PGEA) has been successfully fabricated for multimodal imaging-guided triple-combination treatment of cancer. A hierarchical hetero-structure is first constructed via integration of Au NRs with QDs through a mesoporous silica intermediate layer. The X-ray opacity and photoacoustic (PA) property of Au NRs are utilized for tomography (CT) and PA imaging, and the imaging sensitivity is further enhanced by the fluorescent QDs. The mesoporous feature of silica allows the loading of a typical antitumor drug, doxorubicin (DOX), which are sealed by the polycationic gatekeepers, low toxic hydroxyl-rich CD-PGEA/pDNA complexes, realizing the co-delivery of drug and gene. The photothermal effect of Au NRs is utilized for photothermal therapy (PTT). More interestingly, such photothermal effect also induces a cascade of NIR-triggered release of DOX through the facilitated detachment of CD-PGEA gatekeepers for controlled chemotherapy. The resultant chemotherapy and gene therapy for glioma tumors are complementary for the efficiency of PTT. This work presents a novel responsive multifunctional imaging-guided therapy platform, which combines fluorescent/PA/CT imaging and gene/chemo/photothermal therapy into one nanostructure.

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