MoS2 nanosheet induced destructive alterations in the Escherichia coli bacterial membrane

Broad Adaptability of Coronavirus Adhesion Revealed from the Complementary Surface Affinity of Membrane and Spikes

Coronavirus stands for a large family of viruses characterized by protruding spikes surrounding a lipidic membrane adorned with proteins. The present study explores the adhesion of transmissible gastroenteritis coronavirus (TGEV) particles on a variety of reference solid surfaces that emulate typical virus-surface interactions. Atomic force microscopy informs about trapping effectivity and the shape of the virus envelope on each surface, revealing that the deformation of TGEV particles spans from 20% to 50% in diameter. Given this large deformation range, experimental Langmuir isotherms convey an unexpectedly moderate variation in the adsorption-free energy, indicating a viral adhesion adaptability which goes beyond the membrane. The combination of an extended Helfrich theory and coarse-grained simulations reveals that, in fact, the envelope and the spikes present complementary adsorption affinities. While strong membrane-surface interaction lead to highly deformed TGEV particles, surfaces with strong spike attraction yield smaller deformations with similar or even larger adsorption-free energies.

Stability of Cytoplasmic Membrane of Escherichia coli Bacteria in Aqueous and Ethanolic Environment

The mechanism of action of any antibacterial agent or disinfectant depends largely on their interaction with the bacterial membrane. Herein, we use the SPICA (surface property fitting coarse graining) force-field and develop a coarse-grained (CG) model for the structure of the cytoplasmic membrane of Escherichia coli (E. coli) and its interaction with water and ethanol. We elucidate the impact of different concentrations of ethanol on the cytoplasmic membrane bilayers and vesicles of E. coli using the CG molecular dynamics (CG MD) simulations. Our modeling approach first focuses on the parametrization of the required force-field for POPG lipid and its interaction with water, ethanol, and POPE lipid. Subsequently, the structural stability of the E. coli bacterial membrane in the presence of high and low concentrations of ethanol is delineated. Both flat bilayers as well as vesicles of E. coli membrane were considered for the CG MD. Our results reveal that, at low ethanol concentrations (<30 mol %), the size of the E. coli vesicles increases with discernible deformations in their shapes. Because of ethanol-induced interdigitation, thinning of the E. coli vesicular membrane is also observed. However, at higher ethanol concentrations (>30 mol %), the integrity of the vesicles is lost because of deteriorating invasion of ethanol molecules into the vesicle bilayer and significant weakening of lipid-lipid interactions. At higher ethanol concentrations (40 and 70 mol %), both the multivesicle and single-vesicle bacterial membranes exhibit a similar rupturing pattern wherein the extraction of lipids from the membrane and formation of aggregates of the component lipids are observed. These aggregates consist of polar head groups of 3-5 POPE/POPG lipids with intertwined nonpolar tails.

Unveiling the antibacterial strategies and mechanisms of MoS2: a comprehensive analysis and future directions

Antibiotic resistance is a growing problem that requires alternative antibacterial agents. MoS2, a two-dimensional transition metal sulfide, has gained significant attention in recent years due to its exceptional photocatalytic performance, excellent infrared photothermal effect, and impressive antibacterial properties. This review presents a detailed analysis of the antibacterial strategies and mechanism of MoS2, starting with its morphology and synthesis methods and focusing on the different interaction stages between MoS2 and bacteria. The paper summarizes the main antibacterial mechanisms of MoS2, such as photocatalytic antibacterial, enzyme-like catalytic antibacterial, physical antibacterial, and photothermal-assisted antibacterial. It offers a comprehensive discussion focus on recent research studies of photocatalytic antibacterial mechanisms and categorizes them, guiding the application of MoS2 in the antibacterial field. Overall, the review provides an in-depth understanding of the antibacterial mechanisms of MoS2 and presents the challenges and future directions for the improvement of MoS2 in the field of high-efficiency antibacterial materials.

Interaction of 2D nanomaterial with cellular barrier: Membrane attachment and intracellular trafficking

The cell membrane serves as a barrier against the free entry of foreign substances into the cell. Limited by factors such as solubility and targeting, it is difficult for some drugs to pass through the cell membrane barrier and exert the expected therapeutic effect. Two-dimensional nanomaterial (2D NM) has the advantages of high drug loading capacity, flexible modification, and multimodal combination therapy, making them a novel drug delivery vehicle for drug membrane attachment and intracellular transport. By modulating the surface properties of nanocarriers, it is capable of carrying drugs to break through the cell membrane barrier and achieve precise treatment. In this review, we review the classification of various common 2D NMs, the primary parameters affecting their adhesion to cell membranes, and the uptake mechanisms of intracellular transport. Furthermore, we discuss the therapeutic potential of 2D NMs for several major disorders. We anticipate this review will deepen researchers' understanding of the interaction of 2D NM drug carriers with cell membrane barriers, and provide insights for the subsequent development of novel intelligent nanomaterials capable of intracellular transport.

Robust Mechanical Destruction to the Cell Membrane of Carbon Nitride Polyaniline (C3N): A Molecular Dynamics Simulation Study

The drug-resistant bacteria, particularly multidrug-resistant bacteria, has emerged as a major global public health concern posing serious threats to human life and survival. Nanomaterials, including graphene, have shown promise as effective antibacterial agents owing to their unique antibacterial mechanism compared with traditional drugs. Despite the structural similarity to graphene, the potential antibacterial activity of carbon nitride polyaniline (C₃N) remains unexplored. In this study, we employed molecular dynamics simulations to investigate the effects of the interaction between the C₃N nanomaterial and the bacterial membrane to evaluate the potential antibacterial activity of C₃N. Our results suggest that C₃N is capable of inserting deep into the bacterial membrane interior, regardless of the presence or absence of positional restraints in the C₃N. The insertion process also resulted in local lipid extraction by the C₃N sheet. Additional structural analyses revealed that C₃N induced significant changes in membrane parameters, including mean square displacement, deuterium order parameters, membrane thickness, and area per lipid. Docking simulations, where all the C₃N are restraint to a specific positions, confirmed that C₃N can extract lipids from the membrane, indicating the strong interaction between the C₃N material and the membrane. Free-energy calculations further revealed that the insertion of the C₃N sheet is energetically favorable and that C₃N exhibits membrane insertion capacity comparable to that observed for graphene, suggesting their potential for similar antibacterial activity. This study provides the first evidence of the potential antibacterial properties of C₃N nanomaterials via bacterial membrane damage and underscores the potential for its use as antibacterial agents in the future applications.

Wrapping-Trapping versus Extraction Mechanism of Bactericidal Activity of MoS2 Nanosheets against Staphylococcus aureus Bacterial Membrane

The promising broad-spectrum antibacterial activity of two-dimensional molybdenum disulfide (2D MoS₂) has been widely recognized in the past decade. However, a comprehensive understanding of how the antibacterial pathways opted by the MoS₂ nanosheets varies with change in lipid compositions of different bacterial strains is imperative to harness their full antibacterial potential and remains unexplored thus far. Herein, we present an atomistic molecular dynamics (MD) study to investigate the distinct modes of antibacterial action of MoS₂ nanosheets against Staphylococcus aureus (S. aureus) under varying conditions. We observed that the freely dispersed nanosheets readily adhered to the bacterial membrane outer surface and opted for an unconventional surface directed "wrapping-trapping" mechanism at physiological temperature (i.e., 310 K). The adsorbed nanosheets mildly influenced the membrane structure by originating a compact packing of the lipid molecules present in its direct contact. Interestingly, these surface adsorbed nanosheets exhibited extensive phospholipid extraction to their surface, thereby inducing transmembrane water passage analogous to the cellular leakage, even at a slight increment of 20 K in the temperature. The strong van der Waals interactions between lipid fatty acyl tails and MoS₂ basal planes were primarily responsible for this destructive phospholipid extraction. In addition, the MoS₂ nanosheets bound to an imaginary substrate, controlling their vertical alignment, demonstrated a "nano-knives" action by spontaneously piercing inside the membrane core through their sharp corner, subsequently causing localized lipid ordering in their vicinity. The larger nanosheet produced a more profound deteriorating impact in all of the observed mechanisms. Keeping the existing knowledge about the bactericidal activity of 2D MoS₂ in view, our study concludes that their antibacterial activity is strongly governed by the lipid composition of the bacterial membrane and can be intensified either by controlling the nanosheet vertical alignment or by moderately warming up the systems.