The rational design of alternative antimicrobial materials with reduced toxicity toward mammalian cells is highly desired due to the growing occurrence of bacteria resistant to conventional antibiotics. A promising approach is the design of lipid-based antimicrobial nanocarriers. However, most of the commonly used polymer-stabilized nanocarriers are cytotoxic. Herein, the design of a novel, stabilizer-free nanocarrier for the human cathelicidin derived antimicrobial peptide LL-37 that is cytocompatible and promotes cell proliferation for improved wound healing is reported. The nanocarrier is formed through the spontaneous integration of LL-37 into novel, stabilizer-free glycerol monooleate (GMO)-based cubosomes. Transformations in the internal structure of the cubosomes from Pn3m to Im3m-type and eventually their transition into small vesicles and spherical micelles are demonstrated upon the encapsulation of LL-37 into their internal bicontinuous cubic structure using small angle X-ray scattering, cryogenic transmission electron microscopy, and light scattering techniques. Additional in vitro biological assays show the antimicrobial activity of the stabilizer-free nano-objects on a variety of bacteria strains, their cytocompatibility, and cell-proliferation enhancing effect. The results outline a promising strategy for the comprehensive design of antimicrobial, cytocompatible lipid nanocarriers for the protection and delivery of bioactive molecules with potential for application as advanced wound healing materials.

Functional coatings based on self-assembled lyotropic liquid crystals have the potential for applications such as biosensing, drug delivery and nanotemplating. Here we demonstrate the design and in-depth characterization of glycerol monooleate based liquid crystalline coatings on silicon wafers using drop casting and spin coating techniques. In situ time-resolved grazing incidence small angle X-ray scattering (GISAXS) measurements were used to monitor the coating formation and its response to increasing relative humidity conditions between 5 and 100%. Additional atomic force microscopy (AFM) measurements were applied to visualize the coating nanostructure. Structural transformations through ordered intermediate phases to the sponge- and lamellar phase were observed during ethanol evaporation. Relative humidity dependent GISAXS results revealed gradual phase transitions from the lamellar via the gyroid type cubic phase to the diamond type bicontinuous cubic structure between 5 and 100% relative humidity. The detailed insights into the formation and transformation of the coating nanostructures in this system may provide essential knowledge for the comprehensive design of functional nanostructured surfaces in biomedical applications.

No abstract

Surface-associated microbial infections and contaminations are a major challenge in various fields including the food and health sectors. This study demonstrates the design of antimicrobial coatings based on the self-assembly of the food-grade amphiphilic lipid glycerol monooleate with the human cathelicidin-derived antimicrobial peptide LL-37. Structural properties of the coating and their alterations with composition were studied using advanced experimental methods including synchrotron grazing-incidence small-angle X-ray scattering and ellipsometry. The integration of the LL-37 and its potential release from the nanostructured films into the surrounding solution was characterized with confocal Raman microscopy. Additional biological evaluation studies with clinically relevant bacterial strains, namely, Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive), were performed to investigate the antimicrobial activity of the coatings. Significant killing activity of the coating was found against both bacterial strains. The presented findings contribute to the fundamental understanding of lipid–peptide self-assembly on the surface and may open up a promising strategy for designing simple, sustainable antimicrobial coatings for medical and food applications.

Colloidal lithography (CL) has evolved as an alternative to conventional photo‐ and electron‐beam lithography to pattern surfaces with nanometer range resolution. As CL offers substrate‐independent precise positioning and patterning of nanomaterials as long‐range ordered crystals, this has seen new opportunities in optoelectronics. Herein, the scope of CL is expanded to fabricate for the first time, 3D organic–inorganic heterojunction photocatalysts with well‐controlled spacing and coverage density. To achieve this, monodisperse polystyrene (PS) beads of different sizes are used as colloidal masks on a ZnO substrate. Electron beam assisted silver deposition onto these PS masks, and subsequent removal of PS lead to the formation of patterns of silver nanostars on the ZnO thin film. The solid–vapor reaction of silver nanostars with a metal‐coordinating charge‐transfer complex of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) allows spontaneous conversion of Ag nanostars to the large aspect ratio nanowires of metal–organic AgTCNQ semiconductors. This strategy, combining the strengths of CL with high electron affinity of TCNQ molecules allows facile fabrication of long‐range patterns of the heterojunctions of organic (AgTCNQ) and inorganic (ZnO) semiconductors. These surface‐supported 3D heterojunctions act as outstanding photocatalysts through their ability to efficiently separate the electron–hole pairs and thus increasing the electron–hole life times.

Molecular dynamics simulations of glycerol-monooleate (GMO)/LL-37 nanocarriers show that hydrophobic interactions among the molecules drive the formation of GMO/LL-37 micelles.

Colloidal structures are crucial components in biological systems and provide a vivid and seemingly infinite source of inspiration for the design of functional bio-inspired materials. They form multi-dimensional confinements and shape living matter, and transport and protect bioactive molecules in harsh biological environments such as the stomach. Recently, colloidal nanostructures based on natural antimicrobial peptides have emerged as promising alternatives to conventional antibiotics. This contribution summarizes the recent progress in the understanding and design of these bio-inspired antimicrobial nanomaterials, and discusses their advances in the form of dispersions and as surface coatings. Their potential for applications in future food and healthcare materials is also highlighted. Further, it discusses challenges in the characterization of structure and dynamics in these materials.

Since the start of the current COVID-19 pandemic, for the first time a significant fraction of the world's population cover their respiratory system for an extended period with mostly medical facemasks and textile masks. This new situation raises questions about the extent of mask related debris (fibers and particles) being released and inhaled and possible adverse effects on human health. This study aimed to quantify the debris release from a textile-based facemask in comparison to a surgical mask and a reference cotton textile using both liquid and air extraction. Under liquid extractions, cotton-based textiles released up to 29'452 ± 1'996 fibers g− 1 textile while synthetic textiles released up to 1'030 ± 115 fibers g− 1 textile. However, when the masks were subjected to air-based extraction scenarios, only a fraction (0.1–1.1%) of this fiber amount was released. Several metals including copper (up to 40.8 ± 0.9 µg g− 1) and iron (up to 7.0 ± 0.3 µg g− 1) were detected in acid dissolved textiles. Additionally the acute in vitro toxicity of size-fractionated liquid extracts (below and above 0.4 µm) were assessed on human alveolar basal epithelial cells. The current study shows no acute cytotoxicity response for all the analyzed facemasks.