Drug-resistant bacteria, using their dense cell membranes as strong barrier, significantly reduce the efficacy of conventional antibacterial treatments. Phototriggered 2D catalytic nanomaterials have emerged as promising candidates against drug-resistant bacteria by inducing membrane mechanical damage and generating reactive oxygen species (ROS). However, the practical antibacterial efficacy of typical 2D graphitic carbon nitride (g-C₃N₄) is severely limited due to the low ROS production. Herein, we report an interfacial band-engineered lamellar heterojunctions (MnCN LHJs) through in situ Mn₂O₃ growth on g-C₃N₄. The charges generated in g-C₃N₄ are stabilized by Mn₂O₃, minimizing electron-hole recombination and boosting ROS production. Meanwhile, the photocatalytic effect of MnCN LHJs works synergistically with photothermal effects of Mn₂O₃ to induce a robust “melee attack” against drug-resistant bacteria. High-resolution synchrotron radiation X-ray tomography directly visualized that MnCN LHJs possessed bacterial trapping capabilities, revealing their ability to induce mechanical damage to bacteria membrane for the first time. Additionally, MnCN LHJs can deplete endogenous glutathione, thereby enhancing ROS generation and weakening the bacterial antioxidant defense system. These combined effects achieve a remarkable bactericidal rate exceeding 98% against methicillin-resistant Staphylococcus aureus (MRSA). Notably, MnCN LHJs demonstrate prolonged retention at wound sites, helping to reduce inflammation and promote angiogenesis in infected wounds. This work not only advances interfacial band engineering approach to enhance the photocatalytic performance of g-C₃N₄ but also underscores the significance of nanomaterial–bacteria interaction in design of next-generation antibacterial materials.

Vaccines that are reliable and efficacious are essential in the fight against the COVID-19 pandemic. In this study, we designed a dual-adjuvant system with two pathogen-associated molecular patterns (PAMPs), MnO_x and CpG. This system can improve the retention of antigens at the injection site, facilitate pro-inflammatory cytokines secretion, further recruit and activate dendritic cells (DCs). As a result, antigens can be delivered to lymph nodes specifically, and adaptive immunity was strengthened. The immunized group showed an enhanced and broadened humoral and cellular immune response in systemic immunity and lung protection when combined with a tandem repeat-linked dimeric antigen version of the SARS-CoV-2 receptor binding domain (RBD_dimer). Remarkably, even with a significant reduction in antigen dosage (three times lower) and a decrease in injection frequencies, our nanovaccine was able to produce the highest neutralizing antibody titers against various mutants. These titers were four-fold higher for the wild-type strain and two-fold higher for both the Beta and Omicron variants in comparison with those elicited by the Alum adjuvant group. In conclusion, our dual-adjuvant formulation presents a promising protein subunit-based candidate vaccine against SARS-CoV-2.