Bacterial infections are the most serious worldwide health problems, that seriously constraints the improvement of human living standards [1,2]. As the broad-spectrum antibacterial strategy, the abuse of antibiotics leads to the emergence of a large number of super resistant bacteria [3,4]. Especially, when the infection with antibiotic-resistant bacteria occurs at the wound site, the wound healing becomes more difficult [5]. Hence, the limitations and adverse effects associated with conventional antibiotic therapy have necessitated the exploration of alternative approaches. The advancement of diagnostic and therapeutic agents targeting drug-resistant bacteria plays a significant role in addressing clinical traumas [6,7]. At present, countless number of fashionable therapeutic modalities, such as catalytic therapy [8], phototherapy [9], sonotherapy [10], gaseous therapy [11] and so forth [12], have been developed to effectively combat bacterial infections.

Proteins, which are essential constituents of life, have attracted growing interest due to the advancement of bioactive substances [13]. Which are renowned for their exceptional biocompatibility and inherent therapeutic properties, have emerged as highly promising options for a varirty of applications such as regenerative medicine [14], medical interventions [15], and tissue engineering [16]. Notably, protein-based hydrogels have potential in numerous tissue engineering applications, including wound management [17] and the regeneration of cartilage [18].

Phototherapy, including photothermal therapy (PTT), photodynamic therapy (PDT), etc., refers to the use of photo irradiation to disrupt intracellular metabolism for therapeutic purposes. Among all, PTT has garnered significant interest in fighting against drug-resistant bacterial infections and tumor invasions owing to its advantages such as non-invasive intervention, temporal and spatial controllability, and minimal adverse effects [19,20]. Thus far, most studies have focused on the innovation of photothermal responsive materials especially for near-infrared (NIR) light response. To date, some inorganic materials including transition metal nanoparticles, carbon nanomaterials, and iron oxide nanoparticles [21,22]. and organic materials including heptamethine [[23], [24], [25]], phthalocyanine [26,27], organic semiconducting materials [28] have been extensively investigated. Although these photothermal materials exhibit favorable absorption properties or stabilities, they often do not possess both therapeutic capability and biocompatibility.

In the last few years, engineered living materials have been extensively investigated through the cross development of synthetic biology and materials science because of their environmental responsiveness, sustainability [29]. By combining biological metabolism with material properties, these living materials are particularly promising for combating bacterial infections and promoting wound healing through the concept of “fighting bacteria with bacteria”. Such materials also show therapeutic capability and biocompatibility, thus are suitable for clinical applications. Meanwhile, some key signaling molecules secreted by living chassis can act as metabolite signaling molecules to regulate metabolism and intracellular cytokines, thereby reversing inflammation and wound infections. For example, Deng et al. developed an engineered bacteria-activated multifunctional material by co-embedding living lactococcus in a heparin poloxamer hydrogel to bioengineer wound microenvironment and enhance angiogenesis in a highly dynamic-temporal manner [30]. Besides, in the development of photothermal living materials, engineered photothermal bacteria is also one of the most studied living species, due to their outstanding photothermal response, especially in the NIR-II region (1000-1700 nm) [31]. It can effectively convert light into heat under near-infrared laser irradiation. Therefore, the development of advanced multifunctional photothermal living materials for combating bacterial infections and promoting wound healing has gained considerable attention.

To facilitate the therapeutic outputs for bacteria infection and to spatiotemporally restrict the infection of engineered bacteria, herein, a biocompatible, multimodal, engineered living protein hydrogel patch was developed through combining engineered photothermal bacteria with protein hydrogel platform for combined reactive oxygen species (ROS) and photothermal therapies of bacteria. Melanin-genetic engineered Escherichia coli (EM) was constructed and used for in vivo expression of melanin granules, which showed good photothermal response. Positively charged tetramethylpyridinium porphyrin (TMPyP) was adsorbed on the surface of EM (EMT) to facilitate the photo-mediated generation of highly toxic singlet oxygen (1O2) by avoiding aggregation and enhancing the quantum yield for PDT antibacterial [32] (Scheme 1a). Laccase (Lac), a copper-containing polyphenol oxidase, was introduced to catalyze the generation of toxic ROS in aerobic conditions in the presence of lignin [33,34]. Finally, the engineered EMT biohybrid and Lac enzyme (EMTL@Gel) were co-embedded in a biocompatible bovine serum albumin (BSA) hydrogel patch through crosslinking using glutaraldehyde (Scheme 1b and 1c). The EMTL@Gel patch not only reduced the diffusion of engineered EM bacteria, but also had synergistic antibacterial effects against both gram-negative and gram-positive bacteria through combined photothermal, photodynamic, and catalytic therapy in the presence of photo irradiation and lignin agent (Scheme 1d). The engineered living patch also exhibited wound-healing effects on bacteria-infected skin wounds of mouse (Scheme 1e).