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Crystalline and porous metal–organic frameworks (MOFs) are potential candidates for different antibacterial, photocatalytic, and adsorption applications. Moreover, multiprincipal element nanoparticles are effective against multidrug‐resistant bacteria, and combining metals with carbon nanomaterials can enhance activity. Herein, a Tri‐MOF comprised of iron, zinc, cobalt and 2‐methyl imidazole is grown together with laser‐induced graphene (LIG) powder. Electron microscopy imaging shows the successful preparation and the crystalline nature of the LIG/Tri‐MOF composite. Fourier‐transform infrared and X‐Ray photoelectron spectroscopy confirm a noncovalent mixture of LIG and Tri‐MOF. Compared with the negligible activity of LIG alone, low doses (0.91–4.54 mg mL−1) of the prepared LIG/Tri‐MOF composite show excellent antibacterial activity (≥95% bacterial removal) and a MIC of 0.6 mg mL−1 for Gram‐negative bacteria, via the gradual leaching of metal ions and organic linker from the material enhanced by bacterial aggregation near the LIG/Tri‐MOF. Compared to a mixture of separately synthesized Tri‐MOF and LIG, the LIG/Tri‐MOF composite shows improved antibacterial effects. All materials show cytotoxicity for L929 mouse cell lines, the solids showing a disrupting effect on cells grown in vitro. Performance‐enhancing combinations of various materials leading to synergistic or additive antimicrobial effects are essential strategies for minimizing the possible emergence of antibiotic‐resistant strains. [ABSTRACT FROM AUTHOR]

Protein-based biomaterials are in high demand due to their high biocompatibility, non-toxicity, and biodegradability. In this study, we explore the bacterial E. coli secreted protein A (EspA), which self-assembles into long extracellular filaments, as a potential building block for new protein-based biomaterials. We investigated the morphological and mechanical properties of EspA filaments and how protein engineering can modify them. Our study include three types of filaments: natural EspA filaments, full-length recombinant EspA filaments, and truncated recombinant EspA filaments lacking a third of the original codon region. The recombinant EspA proteins formed curly, thin filaments with higher longitudinal elasticity (shorter persistence length) compared to the natural, linear filaments. Additionally, the recombinant filaments had a radial elastic modulus about an order of magnitude lower than the natural filaments. The truncated recombinant filaments had a higher radial modulus than the full-length ones, and unlike the purely elastic natural filaments, recombinant filaments were less compliant with the applied force that penetrated them. These differences underscore the potential to modulate EspA filament properties through protein sequence mutations. Our findings suggest EspA as a fundamental element for developing a new biomaterial with a hierarchical structure, enabling the fabrication of macroscopic substances from self-assembled EspA-modulated filaments., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

The type III secretion system (T3SS) is crucial for the virulence of several pathogenic Escherichia coli species as well as for other gram-negative bacterial strains. Therefore, the ability to monitor this system constitutes a valuable tool for assessing the involvement of different proteins in bacterial virulence, for identifying critical domains and specific mutations, and for evaluating the antivirulence activities of various drugs. The major advantage of the T3SS secretion assay for E. coli over assays for other gram-negative pathogens is that it does not necessarily require specific antibodies. Here, we describe how to grow enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) strains under T3SS-inducing conditions, separate the supernatant fraction from the bacterial pellet, analyze this fraction on sodium dodecyl sulfate (SDS)-polyacrylamide gels, and evaluate the level of T3SS activity. We describe a qualitative analysis using Coomassie staining and a quantitative assay using western blotting., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)