Self-assembling nanometer-scale structured peptide polymers and peptide dendrimers have shown promise in biomedical applications due to their versatile properties and easy availability. Herein, self-assembling peptide dendron nanoparticles (SPDNs) with potent antimicrobial activity against a range of bacteria were developed based on the nanoscale self-assembly of an arginine–proline repeat branched peptide dendron bearing a hexadecanoic acid chain. The SPDNs are biocompatible, and our most active peptide dendron nanoparticle, C16-3RP, was found to have negligible toxicity after both in vitro and in vivo studies. Furthermore, the C16-3RP nanoparticles showed excellent stability under physiological concentrations of salt ions and against serum and protease degradation, resulting in highly effective treatment in a mouse acute peritonitis model. Comprehensive analyses using a series of biofluorescence, microscopy, and transcriptome sequencing techniques revealed that C16-3RP nanoparticles kill Gram-negative bacteria by increasing bacterial membrane permeability, inducing cytoplasmic membrane depolarization and drastic membrane disruption, inhibiting ribosome biogenesis, and influencing energy generation and other processes. Collectively, C16-3RP nanoparticles show promising biocompatibility and in vivo therapeutic efficacy without apparent resistance development. These advancements may facilitate the development of peptide-based antibiotics in clinical settings.

Although antimicrobial peptides (AMPs) hold tremendous promise in overcoming the threats of multidrug resistance, the main obstacle to successful therapeutic applications is their poor stability. Various synthetic strategies such as unnatural amino acids and chemical modifications have made advances for improving this problem. However, this complicated synthesis often greatly increases the cost of production. Here, we show that a series of novel peptides, designed by combining an α-helical coiled coil model, knowledge of the specificity of proteolysis and major parameters of AMPs, exhibited efficient activity against all tested Gram-negative bacteria under acidic condition and demonstrate low toxicity. Of these α-helical coiled coil peptides, 3IH3 displayed the highest average therapeutic index (GMTI = 294.25) with high stability toward salts, serum, extreme pH, heat, and proteases. Electron microscopy and biological analytical technique analyses showed that 3IH3 killed bacterial cells via a multicomplementary mechanism at pH 6.0, with physical membrane disruption as the dominant bactericidal mechanism. These results suggest that 3IH3 shows great stability as an inexpensive and effective antimicrobial activity agent and has the potential for clinical application in the treatment of infections occurring in body sites with acidic pH.

Antimicrobial peptides (AMPs) are expected to solve problem of antibiotic resistance because of their distinctive nonspecific membrane-disruptive mechanism. However, clinical applications of AMPs have been precluded by their poor stability, although various complex chemical strategies have been employed to solve this problem, and this undoubtedly greatly increases the manufacturing cost. Herein, a series of novel peptides with high stability were developed based on protease-specific cleavage sites and symmetrical end-tagging. Among these peptides, II-I 4 -II exhibited the best antibacterial activity and the highest therapeutic index. More importantly, II-I 4 -II showed extremely high stability in the presence of various proteases, physiological salts and serum, and under acid, alkali, and heat conditions, and it exhibited excellent therapeutic potential in vivo. Additionally, II-I 4 -II exhibited a membrane-disruptive mechanism and a low propensity to induce resistance. In general, these findings contribute to the design of AMPs with high stability and might accelerate clinical applications of AMPs.

Novel antimicrobial peptides (AMPs) have revolutionarily evolved into formidable candidates for antibiotic substitute materials against pathogenic infections. However, cost, lability, disorderly sequences, systemic toxicology, and biological profiles have plagued the perennial search. Here, a progressive β‐hairpin solution with the simplest formulation is implanted into an AMP‐based therapeutic strategy to systematically reveal the complex balance between function and toxicity of structural moieties, including cationicity, hydrophobicity, cross‐strand interactions, center bending, and sequence pattern. Comprehensive implementation of structural identification, ten microorganisms, eleven in vitro barriers, four mammalian cells, and a diversified membrane operation setup led to the emergence of β‐hairpin prototypes from a 24‐member library. Lead amphiphiles, WKF‐PG and WRF‐NG, can tackle bacterial infection through direct antimicrobial efficacy and potential inflammation‐limiting capabilities, such as an Escherichia coli challenge in a mouse peritonitis‐sepsis model, without observed toxicity after systemic administration. Their optimal states with dissimilar modulators and the unavailable drug resistance related to membrane lytic mechanisms, also provide an usher for renewed innovation among β‐sheet peptide‐based antimicrobial biomaterials.

Unlike traditional broad-spectrum antibacterial agents, specifically targeted antimicrobial peptides (STAMPs) are difficult for bacteria to develop resistance to due to their unique membrane lytic mechanism. Additionally, STAMPs can maintain a normal ecological balance and provide long-term protection to the body. However, therapeutic applications of STAMPS are hindered by their weak activity and imperfect specificity, as well as lack of knowledge in understanding their structure–activity relationships. To investigate the effects of different parameters on the biological activities of STAMPs, a peptide sequence, WKKIWKDPGIKKWIK, was truncated, extended, and provided with an increased charge and altered amphipathicity. In addition, a novel template modification method for attaching a phage-displayed peptide, which recognized and bound to Escherichia coli (E. coli) cells, to the end of the sequence was introduced. Compared with the traditional template modification method, peptide 13, which contained a phage-displayed peptide at the C-terminus, exhibited superior narrow-spectrum antibacterial activity against E. coli compared to that of parental peptide 2, and the activity and specificity of peptide 13 were increased by 5.0 and 2.4 times, respectively. Additionally, peptide 13 showed low cytotoxicity and relatively desirable salt, serum, acid, alkaline and heat stability. In this study, peptide 13 specifically killed E. coli by causing cytoplasmic membrane rupture and cytosol leakage. In summary, these findings are useful for improving the activity and specificity of STAMPs and show that peptide 13 is able to combat the growing threat of E. coli infections.