Using broad-spectrum antibiotics for microbial infection may cause flora disequilibrium, drug-resistance, etc., seriously threatening human health. Here, we design a human defensin-6 mimic peptide (HDMP) that inhibits bacterial invasion in vivo through mimicking the mechanisms of human defensin-6 with high efficiency and precision. The HDMP with ligand and self-assembling peptide sequence recognizes bacteria through ligand-receptor interactions and subsequently traps bacteria by an in situ adaptive self-assembly process and resulting nanofibrous networks; these trapped bacteria are unable to invade host cells. In four animal infection models, the infection rate was markedly decreased. Notably, administration of HDMP (5 mg/kg) nanoparticles increased the survival rate of mice with methicillin-resistant S. aureus bacteremia by as much as 100%, even more than that of vancomycin treatment (5 mg/kg, 83.3%)–treated group, the golden standard of antibiotics. This biomimetic peptide shows great potential as a precise and highly efficient antimicrobial agent.

A biomimetic platelet based on assembling peptides initiates artificial coagulation for tumor therapy.

Self-assembling peptides have shown tremendous potential in the fields of material sciences, nanoscience, and medicine. Because of the vast combinatorial space of even short peptides, identification of self-assembling sequences remains a challenge. Herein, we develop an experimental method to rapidly screen a huge array of peptide sequences for self-assembling property, using the one-bead one-compound (OBOC) combinatorial library method. In this approach, peptides on beads are N-terminally capped with nitro-1,2,3-benzoxadiazole, a hydrophobicity-sensitive fluorescence molecule. Beads displaying self-assembling peptides would fluoresce under aqueous environment. Using this approach, we identify eight pentapeptides, all of which are able to self-assemble into nanoparticles or nanofibers. Some of them are able to interact with and are taken up efficiently by HeLa cells. Intracellular distribution varied among these non-toxic peptidic nanoparticles. This simple screening strategy has enabled rapid identification of self-assembling peptides suitable for the development of nanostructures for various biomedical and material applications.

Objectives: Xiaochaihutang (XCHT) has been used in China for thousands of years to treat ‘Shaoyang syndrome’, which involves depressive-like symptoms. However, no studies were conducted to demonstrate its antidepressant effect and mechanism. This study was designed to confirm the antidepressant effect of XCHT and explore its mechanism using the pharmacological methods. Methods: Ultra-HPLC and mass spectrometry was used to identify the chemical constituents of XCHT. Forced swimming test (FST) and tail suspension test (TST) were used to determine the antidepressant-like activity of XCHT in mice and rats. The possible mechanism of XCHT was elucidated by the reserpine-induced hypothermia and 5-hydroxytryptophan (5-HTP)-induced head-twitch in mice. The levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in prefrontal cortex and hippocampus tissue of both mice and rats. Moreover, the extracellular 5-HT in rat hippocampus was assessed by using microdialysis coupled to HPLC with electrochemical detection. Key findings: Forty-four components were detected in XCHT. XCHT significantly reduced immobility time in the TST and the FST, antagonized reserpine-induced depressive-like behaviours, increased 5-HTP-induced head-twitches, elevated 5-HT and 5-HIAA levels, and increased 5-HT turnover at doses that did not affect general activity. Conclusions: These data demonstrate that XCHT has therapeutic effects in animal models of depression by enhancing the serotoninergic system in the prefrontal cortex and hippocampus.

Preventing surgical site infections (SSIs) of implants has drawn significant attention in both basic and clinical research. Implants with convenient preparation methods and intelligent drug release capabilities are highly needed to resist bacterial infection. Herein, we designed an intelligent drug-release system, which can be instantly incorporated with implants during the surgical process. The drug-release system involves β-glycerophosphate (β-GP) and chitosan (CS) as a thermosensitive hydrogel for instant construction onto implants and hyaluronic acid (HA) as a trigger to release vancomycin hydrochloride (VH) on demand. Tertiary calcium phosphate (TCP) scaffolds (implants) are vacuum-adsorbed in a solution of the intelligent vancomycin-release system (VH-HA-CS/β-GP), followed by heating for 40 min at 80 °C to form VH-HA-CS/β-GP@TCP. The drug-release hydrogel intelligently releases vancomycin depending on the concentration of hyaluronidase, which is secreted by Staphylococcus aureus (S. aureus) in infection sites. Furthermore, VH-HA-CS/β-GP@TCP showed effective antibacterial properties in vitro and in vivo. The VH-HA-CS/β-GP drug-release system can be conveniently prepared during surgery for intelligently preventing SSIs in bone tissue.