Rational design yields molecular insights on leaf binding of the anchor peptide Macaque Histatin

In times of a constantly growing world population and increasing demand for food, sustainable agriculture is crucial. To reduce the amount of applied nutrients, herbicides, and fungicides, the rainfastness of plant protection agents is of pivotal importance. As a result of protective agent wash-off, plant protection is lost, and soils and groundwater are severely polluted. To date, rainfastness of plant protection products is achieved by adding polymeric adjuvants to the agrochemicals. However, polymeric adjuvants will be regarded as microplastics in the future, and environmentally friendly alternatives are needed. Anchor peptides (APs) are promising biobased and biodegradable adhesion promoters. While the adhesion of anchor peptides to artificial surfaces, such as polymers, has already been investigated in theory and experimentally, exploiting the adhesion to biological surfaces remains challenging. The complex nature and composition of biological surfaces such as plant leaf and fruit surfaces complicate the generation of accurate models. Here, we present the first detailed three-layered atomistic model of the surface of apple leaves and use it to compute free energy profiles of the adhesion and desorption of APs to and from that surface. Our model is validated by a novel fluorescence-based MTP assay that mimicks these complex processes and allows quantifying them. For the AP Macaque Histatin, we demonstrate that aromatic and positively charged amino acids are essential for binding to the waxy apple leaf surface. The established protocols should generally be applicable for tailoring the binding properties of APs to biological interfaces.

Matching the Cellulose/Silica Films Surface Properties for Design of Biomaterials That Modulate Extracellular Matrix

The surface properties of composite films are important to know for many applications from the industrial domain to the medical domain. The physical and chemical characteristics of film/membrane surfaces are totally different from those of the bulk due to the surface segregation of the low surface energy components. Thus, the surfaces of cellulose acetate/silica composite films are analyzed in order to obtain information on the morphology, topography and wettability through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle investigations. The studied composite films present different surface properties depending on the tetraethyl orthosilicate (TEOS) content from the casting solutions. Up to a content of 1.5 wt.% TEOS, the surface roughness and hydrophobicity increase, after which there is a decrease in these parameters. This behavior suggests that up to a critical amount of TEOS, the results are influenced by the morphology and topographical features, after which a major role seems to be played by surface chemistry—increasing the oxygenation surfaces. The morphological and chemical details and also the hydrophobicity/hydrophilicity characteristics are discussed in the attempt to design biological surfaces with optimal wettability properties and possibility of application in tissue engineering.

Visible blue light inhibits infection and replication of SARS-CoV-2 at doses that are well-tolerated by human respiratory tissue

The delivery of safe, visible wavelengths of light can be an effective, pathogen-agnostic, countermeasure that would expand the current portfolio of SARS-CoV-2 intervention strategies beyond the conventional approaches of vaccine, antibody, and antiviral therapeutics. Employing custom biological light units, that incorporate optically engineered light-emitting diode (LED) arrays, we harnessed monochromatic wavelengths of light for uniform delivery across biological surfaces. We demonstrated that primary 3D human tracheal/bronchial-derived epithelial tissues tolerated high doses of a narrow spectral band of visible light centered at a peak wavelength of 425 nm. We extended these studies to Vero E6 cells to understand how light may influence the viability of a mammalian cell line conventionally used for assaying SARS-CoV-2. The exposure of single-cell monolayers of Vero E6 cells to similar doses of 425 nm blue light resulted in viabilities that were dependent on dose and cell density. Doses of 425 nm blue light that are well-tolerated by Vero E6 cells also inhibited infection and replication of cell-associated SARS-CoV-2 by > 99% 24 h post-infection after a single five-minute light exposure. Moreover, the 425 nm blue light inactivated cell-free betacoronaviruses including SARS-CoV-1, MERS-CoV, and SARS-CoV-2 up to 99.99% in a dose-dependent manner. Importantly, clinically applicable doses of 425 nm blue light dramatically inhibited SARS-CoV-2 infection and replication in primary human 3D tracheal/bronchial tissue. Safe doses of visible light should be considered part of the strategic portfolio for the development of SARS-CoV-2 therapeutic countermeasures to mitigate coronavirus disease 2019 (COVID-19).

HOCl as a promising candidate for effective containment of covid 19 from biological and non-biological surfaces

: Covid 19 is a pandemic disease spread almost in the whole world. To date, no medical advancement to curb the virus. Coronavirus is an enveloped virus transmitted from the biological and non-biological surface by direct or indirect contact. Limited literature revealed that the enveloped virus can be killed by disinfectants. There are many biocidal agents used for decontamination of the virus, yet they have many issues like toxicity, killing time, activation requirement, etc. Some are specific to the inanimate surface but not used by a human being. This situation showed an urgent need for a biocidal agent which can act on biological as well as non-biological surfaces without any potential toxicity. Moreover, it should be easy to handle, inexpensive, and safe for the environment. Hypochlorous acid is a weak acid that acts as a powerful disinfectant and shows biocidal efficacy against a wide range of microorganisms. Hypochlorous acid is simple to use, inexpensive, eco-friendly, non-toxic, and stable. The properties of HOCl can be regulated at the site of preparation and therefore, its compliance is high. Hypochlorous acid seems to be a promising agent in disinfection and sterilization in healthcare facilities. Due to its diverse biocidal actions, it may be used as a potent disinfectant against novel coronavirus.

Closure to Discussion -Fabrication and Testing of Bioinspired Surface Designs for Friction Reduction at the Piston Ring and Liner Interface- [DOI: 10.1115/1.4050795] (2021, ASME J. Tribol., 143(5): 051109)

We thank the discussant for their interest in our manuscript and their very helpful remarks. Existing tribological studies of biomimetic surfaces were mostly focused on dry friction and biological surfaces are highly deformable. Therefore, the learnings on the effects of textures may not be directly translate to fully lubricated interfaces. Nonetheless, we agree that we can still learn much from these studies. Investigating additional orientations of the elongated hexagon could possibly improve the frictional response of the lubricated surfaces. Given that existing literature indicates that orienting the hexagons with two edges perpendicular to the sliding direction yields lower friction than in the case of edges parallel to the sliding direction [1], the experimental conditions in the manuscript could be the worst-case scenario and thus a lower bound for frictional improvement. Additionally, the hexagon was designed based not only on the design of the frog toe (and other natural hexagonal surfaces such as snakes) but also on existing industrial piston cylinder liner designs, where the crossing grooves are oriented nearly perpendicular to the sliding direction [2, 3]. Hence, our tested design is an extension of that existing technology with learning from nature. However, the suggestions to expand the experiment with additional hexagonal orientations is well received and will be considered for future work.

Isolation and Characterization of a Lytic Staphylococcus aureus Phage WV against Staphylococcus aureus Biofilm

<b><i>Background:</i></b> <i>Staphylococcus aureus</i> is a Gram-positive, pathogenic bacterium that causes a wide range of symptoms in humans and can form biofilm, which is a multicellular community of microorganisms that attaches to nonbiological and biological surfaces. <b><i>Methods:</i></b> Here, we aimed to isolate and characterize an <i>S. aureus</i> phage and examine the bactericidal activity alone and in conjunction with streptomycin treatment. <b><i>Results:</i></b> We isolated a virulent phage, WV, from a slaughterhouse in Jiangsu, China. This strain belonged to the family Myoviridae and presented a genome size of 141,342 bp. The optimal pH of the preservation buffer was 6–7, optimal growth temperature was 37°C, and optimal multiplicity of infection was 0.01. Phage WV can sterilize most clinical strains of <i>S. aureus</i> that had been isolated from clinical patients in the First People’s Hospital of the Yunnan Province. Against low-concentration <i>S. aureus</i> culture, streptomycin demonstrated a greater antibiofilm effect than that of phage WV. By contrast, in high-concentration <i>S. aureus</i> culture, phage WV demonstrated greater antibiofilm effect than that of streptomycin. The use of phage WV and streptomycin together had a substantially greater overall antibiofilm effect than that achieved using either component alone. <b><i>Conclusion:</i></b> This study provides strong evidence for the effectiveness of phage application for the reduction of <i>S. aureus</i> biofilm growth and suggests that phages can be considered as a viable alternative to antibiotics in clinical settings.

Hydrophobic-hydrophilic crown-like structure enables aquatic insects to reside effectively beneath the water surface

Various insects utilise hydrophobic biological surfaces to live on the surface of water, while other organisms possess hydrophilic properties that enable them to live within a water column. Dixidae larvae reside, without being submerged, just below the water surface. However, little is known about how these larvae live in such an ecological niche. Herein, we use larvae of Dixa longistyla (Diptera: Dixidae) as experimental specimens and reveal their characteristics. A complex crown-like structure on the abdomen consists of hydrophobic and hydrophilic elements. The combination of these contrasting features enables the larvae to maintain their position as well as to move unidirectionally. Their hydrophobic region leverages water surface tension to function as an adhesive disc. By using the resistance of water, the hydrophilic region serves as a rudder during locomotion.

Stimuli-responsive surfaces for switchable wettability and adhesion

Diverse unique surfaces exist in nature, e.g. lotus leaf, rose petal and rice leaf. They show similar contact angles but different adhesion properties. According to the different wettability and adhesion characteristics, this review reclassifies different contact states of droplets on surfaces. Inspired by the biological surfaces, smart artificial surfaces have been developed which respond to external stimuli and consequently switch between different states. Responsive surfaces driven by various stimuli, e.g. stretching, magnetic, photo, electric, temperature, humidity and pH, are discussed. Studies reporting on either atmospheric or underwater environments are discussed. The application of tailoring surface wettability and adhesion includes microfluidics/droplet manipulation, liquid transport and harvesting, water energy harvesting and flexible smart devices. Particular attention is placed on the horizontal comparison of smart surfaces with the same stimuli. Finally, the current challenges and future prospects in this field are also identified.

The Lubricating Activity of Phospholipids on Charged and Neutral Surfaces

In this paper, the amphoteric character of cartilage surface is used to study friction between charged (+/+), (-/-) and uncharged (±/±) biological surfaces. The surface of the bovine articular cartilage at varying pH solutions is either charged positively or negatively. When examining the coefficient of friction of the (cartilage/cartilage) pair, depending on the pH, we observe surfaces charged positively, negatively and without charge. The uncharged surface refers to the isoelectric point (IEP) and shows greater friction than the charged surfaces of the cartilage. The measurement of surface energy versus pH of the spherical lipid bilayer will reveal the amphoteric nature of the membrane surface. The friction coefficient of the (cartilage/cartilage) pair and the surface energy of the spherical lipid bilayer versus pH are expressed by a bell-shaped curve. This is an interesting case that confirms the fact that the phospholipid bi-layer is embedded on the surface cartilage. This experimental confirmation of negative surface cartilage is insufficiently highlighted in the literature on natural lubrication.