Dual-Mechanism Glycolipidpeptide with High Antimicrobial Activity, Immunomodulatory Activity, and Potential Application for Combined Antibacterial Therapy

Enhancing Antibiotic-Resistant Bacterial Infection Therapy: Self-Assembling Gemini Quaternary Ammonium-Functionalized Peptide Nanoassemblies with Multiple Antibacterial Mechanisms

The rising threat of antimicrobial-resistant (AMR) infections highlights the urgent need for effective antimicrobial agents and therapies. Peptide-based antimicrobial nanomaterials are well-placed to meet this need. Here, we explore the conjugation of antimicrobial gemini quaternary ammonium compounds (GQAs) with designed short hexapeptides to create cationic antimicrobial nanomaterials with low cytotoxicity and minimal resistance tendency. (WA)3GQA8C self-assembles into nanoparticles and exhibits potent antimicrobial activity against drug-resistant pathogens and enhanced stability. (WA)3GQA8C protects against subcutaneous abscess infection and rescues mice from acute peritonitis infection by reducing the systemic bacterial burden and alleviating organ damage, with superior effects to vancomycin. Notably, (WA)3GQA8C thoroughly disrupts bacterial membrane integrity akin to peeling fruit to induce bacterial membrane disintegration, a feat inaccessible to conventional antibiotics. Mechanistic studies suggest that (WA)3GQA8C targets the bacterial membrane phospholipids phosphatidylglycerol (PG), inducing PG deformation to form fibrous or lamellar structures, which leads to the disruption of the bacterial membrane. Furthermore, the interference in lipoprotein trafficking exacerbates damage to bacterial membrane integrity. (WA)3GQA8C also synergizes antimicrobial activity by impairing the protein synthesis function of the ribosome. These quaternized peptide nanoassemblies provide a rational strategy for designing peptide-based antimicrobial nanomaterials to combat the growing threats of resistant bacteria.

Multifunctional cyclic biomimetic peptides: Self-assembling nanotubes for effective treatment of sepsis

Antibiotic abuse has led to an increasingly serious risk of antimicrobial resistance, developing alternative antimicrobials to combat this alarming issue is urgently needed. Rhesus theta defensin-1 (RTD-1) is a theta-defensin contributing to broad-spectrum bactericidal activity via the mechanisms of membrane perturbation. Intriguingly, human defensin-6 (HD6), an enteric defensin secreted by Paneth cells without direct bactericidal effect, could self-assembled into fibrous networks to trap enteric pathogens for assistance of innate immunity. The direct bactericidal action of RTD-1 and the bacterial trapping of HD6 inspire a promising antimicrobial paradigm for unique antibacterial strategies. In this study, we utilized the principle of alternating arrangement of D- and L-amino acids in cyclic peptides, which endows them with the potential to self-assemble into nanotubes, mimic the antimicrobial processes of RTD-1 and HD6. We designed and synthesized five cyclic biomimetic peptides (CBPs), among these biomimetics, CBP-4, which possessed a nanotube-like structure, demonstrated the ability to directly and rapidly disrupt the cell membranes of Gram-positive S. aureus and MRSA, while also targeting the surfaces of Gram-negative E. coil using its nanofibrous network to capture bacteria, preventing invasion and migration, and indirectly killing the bacteria. Moreover, CBP-4 eliminated pathogens, inhibited excessive inflammatory responses caused by infections, and maintained immune system homeostasis in septic mice. By fully emulating the antimicrobial mechanisms of both RTD-1 and HD6, CBP-4 showed promising potential for anti-infectious therapies.

Combating Antibiotic-Resistant Bacterial Infection Using Coassembled Dimeric Antimicrobial Peptide-Based Nanofibers

The emergence of multidrug-resistant (MDR) pathogens, coupled with the limited effectiveness of existing antibiotics in eradicating biofilms, presents a significant threat to global health care. This critical situation underscores the urgent need for the discovery and development of antimicrobial agents. Recently, peptide-derived antimicrobial nanomaterials have shown promise in combating such infections. Amino acid noncovalent forces, notably π-π stacking and electrostatic interactions, remain underutilized for guiding the coassembly of peptides into bacteriostatic nanomaterials. Thus, we constructed a dimeric nanopeptide system using the disulfide bonds of cysteine. The self-assembly of dimeric peptides into nanofibers was realized by the interaction of π-π aromatic amino acids (Trp, Phe, and Pyr) and the electrostatic attraction between oppositely charged amino acids (Asp and Arg). The optimal dimeric peptide 2D2W exhibits potent antibacterial activity against resistant bacteria and is nontoxic. Mechanistically, 2D2W penetrated the outer membrane after electrostatic adsorption, resulting in plasma membrane depolarization, homeostatic disruption, and ultimately bacterial death. In a mouse model of peritonitis, 2D2W demonstrated efficacy in the in vivo treatment of bacterial infections. In conclusion, the design of dimeric nanopeptides co-driven by intermolecular forces provides a promising avenue for the development of high-performance antimicrobial nanomaterials. These advances may also facilitate the application and advancement of peptide-based bacteriostatic agents in clinical practice.

Engineering Robust Silver-Decorated calcium peroxide Nano-Antibacterial Platforms for chemodynamic enhanced sterilization

Calcium peroxide (CaO2) is commonly used as a hydrogen peroxide (H2O2) donor to eliminate bacterial infections. However, the rapid dissociation of CaO2 and the explosive release of H2O2 have limited the development of CaO2 in the antibacterial field. Therefore, a series of silver nanoparticles (AgNPs) functionalized bacteria-triggered smart hydrogels (CSA-H) that integrate sustained release of nanoparticles and localized chemodynamic sterilization were constructed. The pH-responsive hydrogel formed through the Schiff base reaction enables the responsive release of CaO2 nanoparticles while simultaneously regulating the concentration of H2O2 within the bacterial infection microenvironment. AgNPs are capable of reacting with H2O2 under mildly acidic conditions to produce hydroxyl radicals with enhanced antimicrobial activity. The antimicrobial results demonstrated that AgNPs functionalized silicon dioxide-coated calcium peroxide (CaO2@SiO2/AgNPs) nanoparticles exhibited enhanced bactericidal activity compared to AgNPs or CaO2 alone. Furthermore, CSA-H hydrogels exhibited significant antibacterial activity against S. aureus and E. coli under the dual effect of AgNPs and pH-driven Fenton-like reactions. This chemodynamic antibacterial platform is environmentally responsive and provides a promising strategy for creating multifunctional hydrogels loaded with nano-enzymes, thus advancing the development of AgNPs in chemodynamic-antibacterial related applications.

Novel multidomain peptide self-assembly biomaterials based on bola structure and terminal anchoring: Nanotechnology meets antimicrobial therapy

To ameliorate the diminished antimicrobial efficiency and physiological stability associated with monomeric antimicrobial peptides (AMPs) molecules, future research will focus on the artificial design of self-assembling peptides to replace monomeric entities, aiming to combat the antibiotic resistance crisis caused by microbial infections. In this study, the "bola" structure was used as the foundational architecture driving molecular self-assembly, with hydrophobic amino acids at the termini to anchor and finely adjust the sequence, thereby organizing a range of novel multidomain peptides (MDPs) templates into an ABA block motif. The results indicate that FW2 (GMSI = 53.94) exhibits the highest selectivity index among all MDPs and can form spherical micelles in an aqueous medium without the addition of any exogenous additives. FW2 exhibited high stability in vitro in the presence of physiological salt ions, serum, and various pH conditions. It exhibited excellent biocompatibility and efficacy both in vivo and in vitro. Furthermore, FW2 strongly interacts with the lipid membrane and employs various synergistic mechanisms, such as reactive oxygen species (ROS) accumulation, collectively driving cellular apoptosis. This study demonstrates a straightforward strategy for designing self-assembling peptides and promotes the advancement of peptide-based biomaterials integration progress with nanotechnology.

Molybdenum disulfide nanosheets based non-oxygen-dependent and heat-initiated free radical nanogenerator with antimicrobial peptides for antimicrobial, biofilm ablation and wound healing

Chronic refractory wounds caused by multidrug-resistant (MDR) bacterial and biofilm infections are a substantial threat to human health, which presents a persistent challenge in managing clinical wound care. We here synthesized a composite nanosheet AIPH/AMP/MoS2, which can potentially be used for combined therapy because of the photothermal effect induced by MoS2, its ability to deliver antimicrobial peptides, and its ability to generate alkyl free radicals independent of oxygen. The synthesized nanosheets exhibited 61 % near-infrared (NIR) photothermal conversion efficiency, marked photothermal stability and free radical generating ability. The minimal inhibitory concentrations (MICs) of the composite nanosheets against MDR Escherichia coli (MDR E. coli) and MDR Staphylococcus aureus (MDR S. aureus) were approximately 38 μg/mL and 30 μg/mL, respectively. The composite nanosheets (150 μg/mL) effectively ablated >85 % of the bacterial biofilm under 808-nm NIR irradiation for 6 min. In the wound model experiment, approximately 90 % of the wound healed after the 4-day treatment with the composite nanosheets. The hemolysis experiment, mouse embryonic fibroblast (MEFs) cytotoxicity experiment, and mouse wound healing experiment all unveiled the excellent biocompatibility of the composite nanosheets. According to the transcriptome analysis, the composite nanosheets primarily exerted a synergistic therapeutic effect by disrupting the cellular membrane function of S. aureus and inhibiting quorum sensing mediated by the two-component system. Thus, the synthesized composite nanosheets exhibit remarkable antibacterial and biofilm ablation properties and therefore can be used to improve wound healing in chronic biofilm infections.

Harnessing antimicrobial peptides in endodontics

Endodontic therapy includes various procedures such as vital pulp therapy, root canal treatment and retreatment, surgical endodontic treatment and regenerative endodontic procedures. Disinfection and tissue repair are crucial for the success of these therapies, necessitating the development of therapeutics that can effectively target microbiota, eliminate biofilms, modulate inflammation and promote tissue repair. However, no current endodontic agents can achieve these goals. Antimicrobial peptides (AMPs), which are sequences of amino acids, have gained attention due to their unique advantages, including reduced susceptibility to drug resistance, broad-spectrum antibacterial properties and the ability to modulate the immune response of the organism effectively. This review systematically discusses the structure, mechanisms of action, novel designs and limitations of AMPs. Additionally, it highlights the efforts made by researchers to overcome peptide shortcomings and emphasizes the potential applications of AMPs in endodontic treatments.

A Wearable Self-Charging Electroceutical Device for Bacteria-Infected Wound Healing

The prolonged wound-healing process caused by pathogen infection remains a major public health challenge. The developed electrical antibiotic administration typically requires metal electrodes wired to a continuous power supply, restricting their use beyond clinical environments. To obviate the necessity for antibiotics and an external power source, we have developed a wearable synergistic electroceutical device composed of an air self-charging Zn battery. This battery integrates sustained tissue regeneration and antibacterial modalities while maintaining more than half of the initial capacity after ten cycles of chemical charging. In vitro bacterial/cell coculture with the self-charging battery demonstrates inhibited bacterial activity and enhanced cell function by simulating the endogenous electric field and dynamically engineering the microenvironment with released chemicals. This electroceutical device provides accelerated healing of a bacteria-infected wound by stimulating angiogenesis and modulating inflammation, while effectively inhibiting bacterial growth at the wound site. Considering the simple structure and easy operation for long-term treatment, this self-charging electroceutical device offers great potential for personalized wound care.

Optimized Charge/Hydrophobicity Balance of Antimicrobial Peptides Against Polymicrobial Abdominal Infections

Antimicrobial peptides (AMPs) potentially serve as ideal antimicrobial agents for the treatment of polymicrobial abdominal infections due to their broad-spectrum antimicrobial activity and excellent biocompatibility. However, the balance of chain length, positive charges, and hydrophobicity on the antimicrobial activity of AMPs are still far from being optimal. Herein, a series of AMPs ([KX]n-NH2, X = Ile, Leu or Phe, n = 3, 4, 5, or 6) with varied charges and hydrophobicity for the treatment of polymicrobial abdominal infections are designed. Specifically, [KI]4-NH2 peptide exhibits the best in vitro antimicrobial activity against Gram-positive and -negative bacteria, as well as fungal strains. Based on the good cell biocompatibility, [KI]4-NH2 peptide is found to have negligible in vivo toxicity at the dosage of up to 28 mg kg-1. Furthermore, great in vivo therapeutic efficacy of [KI]4-NH2 peptide against S. typhimurium is demonstrated in the mice abdominal infection model. The design of short sequence of antimicrobial peptides with a charge/hydrophobicity balanced structures provides a simple and efficient strategy for potential clinical applications of antimicrobial peptide-based biomaterials in a variety of bacterial infection diseases.

Polysaccharide-Based Coating with Excellent Antibiofilm and Repeatable Antifouling-Bactericidal Properties for Treating Infected Hernia

In recent years, the utilization of medical devices has gradually increased and implantation procedures have become common treatments. However, patients are susceptible to the risk of implant infections. This study utilized chemical grafting to immobilize polyethylenimine (QPEI) and hyaluronic acid (HA) on the surface of the mesh to improve biocompatibility while being able to achieve antifouling antimicrobial effects. From the in vitro testing, PP-PDA-Q-HA exhibited a high antibacterial ratio of 93% against S. aureus, 93% against E. coli, and 85% against C. albicans. In addition, after five rounds of antimicrobial testing, the coating continued to exhibit excellent antimicrobial properties; PP-PDA-Q-HA also inhibits the formation of bacterial biofilms. In addition, PP-PDA-Q-HA has good hemocompatibility and cytocompatibility. In vivo studies in animal implantation infection models also demonstrated the excellent antimicrobial properties of PP-PDA-Q-HA. Our study provides a promising strategy for the development of antimicrobial surface medical materials with excellent biocompatibility.

Engineered Peptides Harboring Cation Motifs Against Multidrug-Resistant Bacteria

Multidrug-resistant (MDR) pathogens pose a serious threat to the health and life of humans, necessitating the development of new antimicrobial agents. Herein, we develop and characterize a panel of nine amino acid peptides with a cation end motif. Bioactivity analysis revealed that the short peptide containing "RWWWR" as a central motif harboring mirror structure "KXR" unit displayed not only high activity against MDR planktonic bacteria but also a clearance rate of 92.33% ± 0.58% against mature biofilm. Mechanically, the target peptide (KLR) killed pathogens by excessively accumulating reactive oxygen species and physically disrupting membranes, thereby enhancing its robustness for controlling drug resistance. In the animal model of sepsis infection by MDR bacteria, the peptide KLR exhibited strong therapeutic effects. Collectively, this study provided the dominant structure of short antimicrobial peptides (AMPs) to replenish our arsenals for combating bacterial infections and illustrated what could be harnessed as a new agent for fighting MDR bacteria.

Turning cationic antimicrobial peptide KR-12 into self-assembled nanobiotics with potent bacterial killing and LPS neutralizing activities

Gram-negative sepsis has become a substantial and escalating global healthcare challenge due to the growing antibiotic resistance crisis and the sluggish development of new antibiotics. LL-37, a unique Cathelicidin species found in humans, exhibits a wide range of bioactive properties, including direct bactericidal effects, inflammation regulation, and LPS neutralization. KR-12, the smallest yet potent peptide fragment of LL-37, has been modified to create more effective antimicrobials. In this study, we designed two myristoylated derivatives of KR-12, referred to as Myr-KR-12N and Myr-KR-12C. These derivatives displayed remarkable ability to spontaneously assemble into nanoparticles when mixed with deionized water. Myristoylated KR-12 derivatives exhibited broad-spectrum and intensified bactericidal activity by disrupting bacterial cell membranes. In particular, Myr-KR-12N showed superior capability to rescue mice from lethal E. coli-induced sepsis in comparison with the conventional antibiotic meropenem. We also confirmed that the myristoylated KR-12 nanobiotic possesses significant LPS binding capacity and effectively reduces inflammation in vitro. In an in vivo context, Myr-KR-12N outperformed polymyxin B in rescuing mice from LPS-induced sepsis. Crucially, toxicological assessments revealed that neither Myr-KR-12N nor Myr-KR-12C nanobiotics induced meaningful hemolysis or caused damage to the liver and kidneys. Collectively, our study has yielded an innovative nanobiotic with dual capabilities of bactericidal action and LPS-neutralization, offering substantial promise for advancing the clinical translation of antimicrobial peptides and the development of novel antibiotics. This addresses the critical need for effective solutions to combat Gram-negative sepsis, a pressing global medical challenge.

Croconaine conjugated cationic polymeric nanoparticles for NIR enhanced bacterial killing

Light-triggered treatment approach has been regarded as an effective option for sterilization due to noninvasiveness, limited drug resistance, and minimized adverse effects. Herein, we designed and synthesized a functionalized cationic polymer, CR-PQAC, with croconaine bridging agent and quaternary ammonium groups for photothermal enhanced antimicrobial therapy under near-infrared irradiation. The quaternary ammonium group on the pendent chain endowing CR-PQAC the ability to effectively bind to bacteria. The CR-PQAC could self-assembles into micellar nanoparticles in aqueous solution, which exhibited strong absorption in the near-infrared (NIR) region, excellent photostability, and photothermal conversion efficiency of up to 43.8 %. Notably, the CR-PQAC nanoparticles presented remarkable antibacterial activity against both methicillin-resistant Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria with 808 nm laser irradiation. Moreover, the developed CR-PQAC has negligible dark cytotoxicity and good hemolytic compatibility against mammalian cells. Both in vitro and in vivo studies have demonstrated that the desirable antibacterial efficacy of CR-PQAC was obtained. Therefore, the proposed CR-PQAC may be a promising antimicrobial agent for NIR-enhanced killing bacterial.

Near-Infrared-Induced NO-Releasing Photothermal Adhesive Hydrogel with Enhanced Antibacterial Properties

Bacterial infection and the development of antibiotic-resistant bacteria have decreased the effectiveness of traditional antibiotic treatments for wound healing. The design of a multifunctional adhesive hydrogel with antibacterial activity, self-healing properties, and on-demand removability to promote wound healing is highly desirable. In this work, a photothermal cyclodextrin with a NO-releasing moiety has been incorporated within an oxidized sodium alginate conjugated polyacrylamide (OS@PA) hydrogel to get a photothermal NO-releasing GSNOCD-OS@PA hydrogel. Such a multifunctional hydrogel has the unique feature of combined antibacterial activity as a result of a controlled photothermal effect and NO gas release under an 808 near-infrared laser. Because of oxidized sodium alginate (OSA), the hydrogel matrix easily adheres to the skin under twisted and bent states. In vitro cytotoxicity analysis against 3T3 cells showed that the hydrogels OS@PA and GSNOCD-OS@PA are noncytotoxic under laser exposure. The temperature-induced NO release by GSNOCD-OS@PA reached 31.7 mg/L when irradiated with an 808 nm laser for 10 min. The combined photothermal therapy and NO release from GSNOCD-OS@PA effectively reduced viability of both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) to 3 and 5%, respectively. Importantly, the phototherapeutic NO-releasing platform displayed effective fibroblast proliferation in a cell scratch assay.