scholarly journals Model-Driven Controlled Alteration of Nanopillar Cap Architecture Reveals its Effects on Bactericidal Activity

2020 ◽  
Vol 8 (2) ◽  
pp. 186 ◽  
Author(s):  
Taiyeb Zahir ◽  
Jiri Pesek ◽  
Sabine Franke ◽  
Jasper Van Pee ◽  
Ashish Rathore ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Cell Envelope ◽  
Antibacterial Properties ◽  
Biophysical Model ◽  
Surface Measurement ◽  
Dependent Manner ◽  
Bending Rigidity ◽  
Nanostructured Surfaces ◽  
Model Driven ◽  
Antibacterial Surfaces

Nanostructured surfaces can be engineered to kill bacteria in a contact-dependent manner. The study of bacterial interactions with a nanoscale topology is thus crucial to developing antibacterial surfaces. Here, a systematic study of the effects of nanoscale topology on bactericidal activity is presented. We describe the antibacterial properties of highly ordered and uniformly arrayed cotton swab-shaped (or mushroom-shaped) nanopillars. These nanostructured surfaces show bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa. A biophysical model of the cell envelope in contact with the surface, developed ab initio from the infinitesimal strain theory, suggests that bacterial adhesion and subsequent lysis are highly influenced by the bending rigidity of the cell envelope and the surface topography formed by the nanopillars. We used the biophysical model to analyse the influence of the nanopillar cap geometry on the bactericidal activity and made several geometrical alterations of the nanostructured surface. Measurement of the bactericidal activities of these surfaces confirms model predictions, highlights the non-trivial role of cell envelope bending rigidity, and sheds light on the effects of nanopillar cap architecture on the interactions with the bacterial envelope. More importantly, our results show that the surface nanotopology can be rationally designed to enhance the bactericidal efficiency.

scholarly journals The multi-faceted mechano-bactericidal mechanism of nanostructured surfaces

2020 ◽  
Vol 117 (23) ◽  
pp. 12598-12605 ◽  
Author(s):  
Elena P. Ivanova ◽  
Denver P. Linklater ◽  
Marco Werner ◽  
Vladimir A. Baulin ◽  
XiuMei Xu ◽  
...  
Keyword(s):  
Cell Death ◽  
Bactericidal Activity ◽  
Mechanical Energy ◽  
Bactericidal Effect ◽  
Bacterial Cells ◽  
Gram Stain ◽  
Nanostructured Surfaces ◽  
Bacterial Cell Death ◽  
Antibacterial Surfaces ◽  
Nanopillar Arrays

The mechano-bactericidal activity of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, particularly in the current era of emerging antibiotic resistance. This work demonstrates the effects of an incremental increase of nanopillar height on nanostructure-induced bacterial cell death. We propose that the mechanical lysis of bacterial cells can be influenced by the degree of elasticity and clustering of highly ordered silicon nanopillar arrays. Herein, silicon nanopillar arrays with diameter 35 nm, periodicity 90 nm and increasing heights of 220, 360, and 420 nm were fabricated using deep UV immersion lithography. Nanoarrays of 360-nm-height pillars exhibited the highest degree of bactericidal activity toward both Gram stain-negativePseudomonas aeruginosaand Gram stain-positiveStaphylococcus aureusbacteria, inducing 95 ± 5% and 83 ± 12% cell death, respectively. At heights of 360 nm, increased nanopillar elasticity contributes to the onset of pillar deformation in response to bacterial adhesion to the surface. Theoretical analyses of pillar elasticity confirm that deflection, deformation force, and mechanical energies are more significant for the substrata possessing more flexible pillars. Increased storage and release of mechanical energy may explain the enhanced bactericidal action of these nanopillar arrays toward bacterial cells contacting the surface; however, with further increase of nanopillar height (420 nm), the forces (and tensions) can be partially compensated by irreversible interpillar adhesion that reduces their bactericidal effect. These findings can be used to inform the design of next-generation mechano-responsive surfaces with tuneable bactericidal characteristics for antimicrobial surface technologies.

scholarly journals A Fish Galectin-8 Possesses Direct Bactericidal Activity

2020 ◽  
Vol 22 (1) ◽  
pp. 376
Author(s):  
Tengfei Zhang ◽  
Shuai Jiang ◽  
Li Sun
Keyword(s):  
Bactericidal Activity ◽  
Bacterial Pathogens ◽  
Bactericidal Effect ◽  
Immune Defense ◽  
Carbohydrate Binding ◽  
Dependent Manner ◽  
Animal Cells ◽  
Gram Negative ◽  
Tongue Sole ◽  
Wide Range

Galectins are a family of animal lectins with high affinity for β-galactosides. Galectins are able to bind to bacteria, and a few mammalian galectins are known to kill the bound bacteria. In fish, no galectins with direct bactericidal effect have been reported. In the present study, we identified and characterized a tandem repeat galectin-8 from tongue sole Cynoglossus semilaevis (designated CsGal-8). CsGal-8 possesses conserved carbohydrate recognition domains (CRDs), as well as the conserved HXNPR and WGXEE motifs that are critical for carbohydrate binding. CsGal-8 was constitutively expressed in nine tissues of tongue sole and up-regulated in kidney, spleen, and blood by bacterial challenge. When expressed in HeLa cells, CsGal-8 protein was detected both in the cytoplasm and in the micro-vesicles secreted from the cells. Recombinant CsGal-8 (rCsGal-8) bound to lactose and other carbohydrates in a dose dependent manner. rCsGal-8 bound to a wide range of gram-positive and gram-negative bacteria and was co-localized with the bound bacteria in animal cells. Lactose, fructose, galactose, and trehalose effectively blocked the interactions between rCsGal-8 and different bacteria. Furthermore, rCsGal-8 exerted potent bactericidal activity against some gram-negative bacterial pathogens by directly damaging the membrane and structure of the pathogens. Taken together, these results indicate that CsGal-8 likely plays an important role in the immune defense against some bacterial pathogens by direct bacterial interaction and killing.

scholarly journals Genetic Analysis of Factors Affecting Susceptibility of Bacillus subtilis to Daptomycin

2009 ◽  
Vol 53 (4) ◽  
pp. 1598-1609 ◽  
Author(s):  
Anna-Barbara Hachmann ◽  
Esther R. Angert ◽  
John D. Helmann
Keyword(s):  
Bacillus Subtilis ◽  
Cell Envelope ◽  
Transcriptional Profiling ◽  
Protein A ◽  
Multidrug Resistant ◽  
Dependent Manner ◽  
Membrane Composition ◽  
Factors Affecting ◽  
Anionic Phospholipids ◽  
Cyclic Lipopeptide

ABSTRACT Daptomycin is the first of a new class of cyclic lipopeptide antibiotics used against multidrug-resistant, gram-positive pathogens. The proposed mechanism of action involves disruption of the functional integrity of the bacterial membrane in a Ca2+-dependent manner. We have used transcriptional profiling to demonstrate that treatment of Bacillus subtilis with daptomycin strongly induces the lia operon including the autoregulatory LiaRS two-component system (homologous to Staphylococcus aureus VraSR). The lia operon protects against daptomycin, and deletion of liaH, encoding a phage-shock protein A (PspA)-like protein, leads to threefold increased susceptibility. Since daptomycin interacts with the membrane, we tested mutants with altered membrane composition for effects on susceptibility. Deletion mutations of mprF (lacking lysyl-phosphatidylglycerol) or des (lipid desaturase) increased daptomycin susceptibility, whereas overexpression of MprF decreased susceptibility. Conversely, depletion of the cell for the anionic lipid phosphatidylglycerol led to increased resistance. Fluorescently labeled daptomycin localized to the septa and in a helical pattern around the cell envelope and was delocalized upon the depletion of phosphatidylglycerol. Together, these results indicate that the daptomycin-Ca2+ complex interacts preferentially with regions enriched in anionic phospholipids and leads to membrane stresses that can be ameliorated by PspA family proteins.

scholarly journals Silver Nanoparticles Impair Cognitive Functions and Modify the Hippocampal Level of Neurotransmitters in a Coating-Dependent Manner

2021 ◽  
Vol 22 (23) ◽  
pp. 12706
Author(s):  
Katarzyna Dziendzikowska ◽  
Małgorzata Węsierska ◽  
Joanna Gromadzka-Ostrowska ◽  
Jacek Wilczak ◽  
Michał Oczkowski ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Spatial Memory ◽  
Antibacterial Properties ◽  
Coating Material ◽  
Long Term Memory ◽  
Avoidance Task ◽  
Dependent Manner ◽  
Memory Functioning ◽  
Place Avoidance ◽  
The Brain

Due to their potent antibacterial properties, silver nanoparticles (AgNPs) are widely used in industry and medicine. However, they can cross the brain–blood barrier, posing a risk to the brain and its functions. In our previous study, we demonstrated that oral administration of bovine serum albumin (BSA)-coated AgNPs caused an impairment in spatial memory in a dose-independent manner. In this study, we evaluated the effects of AgNPs coating material on cognition, spatial memory functioning, and neurotransmitter levels in rat hippocampus. AgNPs coated with BSA (AgNPs(BSA)), polyethylene glycol (AgNPs(PEG)), or citrate (AgNPs(Cit)) or silver ions (Ag+) were orally administered at a dose of 0.5 mg/kg b.w. to male Wistar rats for a period of 28 days, while the control (Ctrl) rats received 0.2 mL of water. The acquisition and maintenance of spatial memory related to place avoidance were assessed using the active allothetic place avoidance task, in which rats from AgNPs(BSA), AgNPs(PEG), and Ag+ groups performed worse than the Ctrl rats. In the retrieval test assessing long-term memory, only rats from AgNPs(Cit) and Ctrl groups showed memory maintenance. The analysis of neurotransmitter levels indicated that the ratio between serotonin and dopamine concentration was disturbed in the AgNPs(BSA) rats. Furthermore, treatment with AgNPs or Ag+ resulted in the induction of peripheral inflammation, which was reflected by the alterations in the levels of serum inflammatory mediators. In conclusion, depending on the coating material used for their stabilization, AgNPs induced changes in memory functioning and concentration of neurotransmitters.

scholarly journals Bacteria Death and Osteoblast Metabolic Activity Correlated to Hydrothermally Synthesised TiO2 Surface Properties

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1201 ◽  
Author(s):  
Alka Jaggessar ◽  
Asha Mathew ◽  
Tuquabo Tesfamichael ◽  
Hongxia Wang ◽  
Cheng Yan ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Metabolic Activity ◽  
Mechanical Stability ◽  
Antibacterial Properties ◽  
Mechanical Tests ◽  
Nanostructured Surfaces ◽  
Surface Contact Angle ◽  
Cellular Metabolic Activity ◽  
Structure Height

Orthopaedic surgery comes with an inherent risk of bacterial infection, prolonged antibiotic therapy and revision surgery. Recent research has focused on nanostructured surfaces to improve the bactericidal and osseointegrational properties of implants. However, an understanding of the mechanical properties of bactericidal materials is lacking. In this work, the surface properties of hydrothermal TiO2 nanostructured surfaces are investigated for their effect on bactericidal efficiency and cellular metabolic activity of human osteoblast cells. TiO2 nanostructures, approximately 307 nm in height and 14 GPa stiffness, were the most effective structures against both gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacteria. Statistical analysis significantly correlated structure height to the death of both bacteria strains. In addition, the surface contact angle and Young’s modulus were correlated to osteoblast metabolic activity. Hydrophilic surfaces with a contact angle between 35 and 50° produced the highest cellular metabolic activity rates after 24 hours of incubation. The mechanical tests showed that nanostructures retain their mechanical stability and integrity over a long time-period, reaffirming the surfaces’ applicability for implants. This work provides a thorough examination of the surface, mechanical and wettability properties of multifunctional hydrothermally synthesised nanostructured materials, capable of killing bacteria whilst improving osteoblast metabolic rates, leading to improved osseointegration and antibacterial properties of orthopaedic implants.

scholarly journals Silver Nanoparticles Induce Mitochondrial Protein Oxidation in Lung Cells Impacting Cell Cycle and Proliferation

Antioxidants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 552 ◽  
Author(s):  
Reetta J. Holmila ◽  
Stephen A. Vance ◽  
S. Bruce King ◽  
Allen W. Tsang ◽  
Ravi Singh ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Silver Nanoparticles ◽  
Ionizing Radiation ◽  
Cell Lines ◽  
Protein Oxidation ◽  
Mitochondrial Protein ◽  
Antibacterial Properties ◽  
Dependent Manner ◽  
Mitochondrial Redox State ◽  
And Function

Silver nanoparticles (AgNPs) are widely used nanomaterials in both commercial and clinical biomedical applications, due to their antibacterial properties. AgNPs are also being explored for the treatment of cancer in particular in combination with ionizing radiation. In this work, we studied the effects of AgNPs and ionizing radiation on mitochondrial redox state and function in a panel of lung cell lines (A549, BEAS-2B, Calu-1 and NCI-H358). The exposure to AgNPs caused cell cycle arrest and decreased cell proliferation in A549, BEAS-2B and Calu-1, but not in NCI-H358. The mitochondrial reactive oxygen species (ROS) and protein oxidation increased in a time- and dose-dependent manner in the more sensitive cell lines with the AgNP exposure, but not in NCI-H358. While ionizing radiation also induced changes in the mitochondrial redox profiles, in general, these were not synergistic with the effects of AgNPs with the exception of NCI-H358 and only at a higher dose of radiation.

Regenerable smart antibacterial surfaces: full removal of killed bacteria via a sequential degradable layer

2018 ◽  
Vol 6 (23) ◽  
pp. 3946-3955 ◽  
Author(s):  
Yangcui Qu ◽  
Ting Wei ◽  
Jian Zhao ◽  
Shuaibing Jiang ◽  
Peng Yang ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Hybrid Film ◽  
Antibacterial Surfaces

An antibiotic-free and regenerable antibacterial hybrid film with both photothermal bactericidal activity and bacteria-releasing properties is fabricated on diverse substrates.

scholarly journals Mechanisms of Resistance to the Contact-Dependent Bacteriocin CdzC/D inCaulobacter crescentus

2019 ◽  
Vol 201 (8) ◽  
Author(s):  
Leonor García-Bayona ◽  
Kevin Gozzi ◽  
Michael T. Laub
Keyword(s):  
Outer Membrane ◽  
Caulobacter Crescentus ◽  
Cell Envelope ◽  
Target Cells ◽  
Dependent Manner ◽  
Content Type ◽  
Repeat Protein ◽  
Outer Membranes ◽  
Oligotrophic Bacterium ◽  
Small Hydrophobic

ABSTRACTThe Cdz bacteriocin system allows the aquatic oligotrophic bacteriumCaulobacter crescentusto kill closely related species in a contact-dependent manner. The toxin, which aggregates on the surfaces of producer cells, is composed of two small hydrophobic proteins, CdzC and CdzD, each bearing an extended glycine-zipper motif, that together induce inner membrane depolarization and kill target cells. To further characterize the mechanism of Cdz delivery and toxicity, we screened for mutations that render a target strain resistant to Cdz-mediated killing. These mutations mapped to four loci, including a TonB-dependent receptor, a three-gene operon (namedzerRABforzipperenveloperesistance), andperA(forpentapeptideenveloperesistance). Mutations in thezerRABlocus led to its overproduction and to potential changes in cell envelope composition, which may diminish the susceptibility of cells to Cdz toxins. TheperAgene is also required to maintain a normal cell envelope, but our screen identified mutations that confer resistance to Cdz toxins without substantially affecting the cell envelope functions of PerA. We demonstrate that PerA, which encodes a pentapeptide repeat protein predicted to form a quadrilateral β-helix, localizes primarily to the outer membrane of cells, where it may serve as a receptor for the Cdz toxins. Collectively, these results provide new insights into the function and mechanisms of an atypical, contact-dependent bacteriocin system.IMPORTANCEBacteriocins are commonly used by bacteria to kill neighboring cells that compete for resources. Although most bacteriocins are secreted, the aquatic, oligotrophic bacteriumCaulobacter crescentusproduces a two-peptide bacteriocin, CdzC/D, that remains attached to the outer membranes of cells, enabling contact-dependent killing of cells lacking the immunity protein CdzI. The receptor for CdzC/D has not previously been reported. Here, we describe a genetic screen for mutations that confer resistance to CdzC/D. One locus identified,perA, encodes a pentapeptide repeat protein that resides in the outer membrane of target cells, where it may act as the direct receptor for CdzC/D. Collectively, our results provide new insight into bacteriocin function and diversity.

scholarly journals Mycobacterial Di-O-Acyl-Trehalose Inhibits Mitogen- and Antigen-Induced Proliferation of Murine T Cells In Vitro

2001 ◽  
Vol 8 (6) ◽  
pp. 1081-1088 ◽  
Author(s):  
Rafael Saavedra ◽  
Erika Segura ◽  
Rosario Leyva ◽  
Luis A. Esparza ◽  
Luz M. López-Marı́n
Keyword(s):  
Cell Division ◽  
Cell Envelope ◽  
Inhibitory Effect ◽  
Host Cells ◽  
Mouse Spleen ◽  
Dependent Manner ◽  
Spleen Cells ◽  
Murine Spleen ◽  
Focus Of Infection

ABSTRACT 2,3-Di-O-acyl-trehalose (DAT) is a glycolipid located on the outer layer of the Mycobacterium tuberculosis cell envelope. Due to its noncovalent linkage to the mycobacterial peptidoglycan, DAT could easily interact with host cells located in the focus of infection. The aim of the present work was to study the effects of DAT on the proliferation of murine spleen cells. DAT was purified from reference strains of M. tuberculosis,or M. fortuitum as a surrogate source of the compound, by various chromatography and solvent extraction procedures and then chemically identified. Incubation of mouse spleen cells with DAT inhibited in a dose-dependent manner concanavalin A-stimulated proliferation of the cells. Experiments, including the propidium iodide exclusion test, showed that these effects were not due to death of the cells. Tracking of cell division by labeling with 5,6-carboxyfluorescein diacetate succinimidyl ester revealed that DAT reduces the rounds of cell division. Immunofluorescence with an anti-CD3 monoclonal antibody indicated that T lymphocytes were the population affected in our model. Our experiments also suggest that the extent of the suppressive activity is strongly dependent on the structural composition of the acyl moieties in DATs. Finally, the inhibitory effect was also observed on antigen-induced proliferation of mouse spleen cells specific for Toxoplasma gondii. All of these data suggest that DAT could have a role in the T-cell hyporesponsiveness observed in chronic tuberculosis.

scholarly journals Antioxidant And Antibacterial Activity Of Methanolic Extract Of Machilus Odoratissima

1970 ◽  
Vol 8 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Amit Subedi ◽  
Mohan Prasad Amatya ◽  
Tirtha Maiya Shrestha ◽  
Shyam Kumar Mishra ◽  
Bharat Mani Pokhrel
Keyword(s):  
Antibacterial Activity ◽  
Methanol Extract ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Antibacterial Properties ◽  
Dependent Manner ◽  
Scavenging Activity ◽  
Deoxy Sugar ◽  
Radical Method ◽  
Dose Dependent

The methanol extract of the bark of Machilus odoratissima was subjected to investigate its antioxidant and antibacterial properties. The phytochemical screening demonstrated the presence of different types of compound like terpenoids, tannins, deoxy sugar, saponins and phenolic compounds. The methanol extract of the plant was tested for antioxidant activity using scavenging activity of DPPH(1,1-diphenyl-2-picrylhydrazil) radical method and antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli & Pseudomonas aeruginosa bacteria using cup plate method. The extract exhibited high free radical scavenging activity. IC50 was found to be 3.37μg/ml. Antibacterial activity was observed against S. aureus in dose dependent manner DOI: http://dx.doi.org/10.3126/kuset.v8i1.6045 KUSET 2012; 8(1): 73-80

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