Antimicrobial Properties and Cytotoxic Effect of Imidazolium Geminis with Tunable Hydrophobicity

Antimicrobial, membranotropic and cytotoxic properties of dicationic imidazolium surfactants of n-s-n (Im) series with variable length of alkyl group (n = 8, 10, 12, 14, 16) and spacer fragment (s = 2, 3, 4) were explored and compared with monocationic analogues. Their activity against a representative range of Gram-positive and Gram-negative bacteria, and also fungi, is characterized. The relationship between the biological activity and the structural features of these compounds is revealed, with the hydrophobicity emphasized as a key factor. Among dicationic surfactants, decyl derivatives showed highest antimicrobial effect, while for monocationic analogues, the maximum activity is observed in the case of tetradecyl tail. The leading compounds are 2–4 times higher in activity compared to reference antibiotics and prove effective against resistant strains. It has been shown that the antimicrobial effect is not associated with the destruction of the cell membrane, but is due to specific interactions of surfactants and cell components. Importantly, they show strong selectivity for microorganism cells while being of low harm to healthy human cells, with a SI ranging from 30 to 100.

Download Full-text

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074768 ◽

1983 ◽

Vol 41 ◽

pp. 194-195

Author(s):

D. F. Blake ◽

L. F. Allard ◽

D. R. Peacor

Keyword(s):

High Resolution ◽

Marine Invertebrates ◽

Sea Urchins ◽

Structural Features ◽

Sea Stars ◽

High Resolution Tem ◽

Relationship Of ◽

The Relationship ◽

Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Download Full-text

Antimicrobial properties of actively purified secondary metabolites isolated from different marine organisms

Current Pharmaceutical Biotechnology ◽

10.2174/1389201021666200730144536 ◽

2020 ◽

Vol 21 ◽

Author(s):

Nilushi Indika Bamunu Arachchige ◽

Fazlurrahman Khan ◽

Young-Mog Kim

Keyword(s):

Secondary Metabolites ◽

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Bacterial Species ◽

Antimicrobial Properties ◽

Antimicrobial Effect ◽

Cost Effective ◽

Resistance Mechanisms ◽

Marine Organisms ◽

Antimicrobial Compounds

Background: The treatment of infection caused by pathogenic bacteria becomes one of the serious concerns globally. The failure in the treatment was found due to the exhibition of multiple resistance mechanisms against the antimicrobial agents. Emergence of resistant bacterial species has also been observed due to prolong treatment using conventional antibiotics. To combat these problems, several alternative strategies have been employed using biological and chemically synthesized compounds as antibacterial agents. Marine organisms considered as one of the potential sources for the isolation of bioactive compounds due to the easily available, cost-effective, and eco-friendly. Methods: The online search methodology was adapted for the collection of information related to the antimicrobial properties of marine-derived compounds. These compound has been isolated and purified by different purification techniques, and their structure also characterized. Furthermore, the antibacterial activities have been reported by using broth microdilution as well as disc diffusion assays. Results: The present review paper describes the antimicrobial effect of diverse secondary metabolites which are isolated and purified from the different marine organisms. The structural elucidation of each secondary metabolite has also been done in the present paper, which will help for the in silico designing of the novel and potent antimicrobial compounds. Conclusion: A thorough literature search has been made and summarizes the list of antimicrobial compounds that are isolated from both prokaryotic and eukaryotic marine organisms. The information obtained from the present paper will be helpful for the application of marine compounds as antimicrobial agents against different antibiotic-resistant human pathogenic bacteria.

Download Full-text

Biologically Important Physicochemical Properties of Some Cephalosporins

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19921739 ◽

1992 ◽

Vol 57 (8) ◽

pp. 1739-1746

Author(s):

Katarína Škvareninová ◽

Štefan Baláž ◽

Ernest Šturdík ◽

Miroslav Veverka ◽

Jana Adamcová ◽

...

Keyword(s):

Physicochemical Properties ◽

Partition Coefficients ◽

Dissociation Constants ◽

Transport Rate ◽

Hydrolysis Rate ◽

Antibacterial Effects ◽

Oh Groups ◽

Non Linear Equation ◽

Cell Components ◽

The Relationship

In the series of cephalosporin derivatives, consisting of eight 7-(R1-CH2-CO-NH)cephalosporanic acids and of seven analogical compounds with 3-acetoxymethyl replaced by 3-CH3, physicochemical properties, which are expected to play a role in their antibacterial effects (the transport rate parameters and partition coefficients in the systems 1-octanol-water and 1-octanol-buffer, dissociation constants of the 4-carboxyl group, reactivity towards L-glutathione imitating the nucleophilic groups of the cell components and hydrolysis rate parameters), were determined. Linear dependences were observed between the partition coefficients and the π-constants of the varying substituents as well as between reactivity towards SH-groups of L-glutathione and OH-groups. The relationship between the transport rate parameters and partition coefficients, both measured in buffered as well as non-buffered system, was described by a common non-linear equation.

Download Full-text

Overdiagnosis and overtreatment of nipple and breast candidiasis: A review of the relationship between diagnoses of mammary candidiasis and Candida albicans in breastfeeding women

Women s Health ◽

10.1177/17455065211031480 ◽

2021 ◽

Vol 17 ◽

pp. 174550652110314

Author(s):

Pamela Douglas

Keyword(s):

Candida Albicans ◽

Human Milk ◽

Signs And Symptoms ◽

Breast Pain ◽

Breastfeeding Support ◽

Candida Spp ◽

Healthy Human ◽

Nipple Areolar Complex ◽

Areolar Complex ◽

The Relationship

Background: Breastfeeding mothers commonly experience nipple pain accompanied by radiating, stabbing or constant breast pain between feeds, sometimes associated with pink shiny nipple epithelium and white flakes of skin. Current guidelines diagnose these signs and symptoms as mammary candidiasis and stipulate antifungal medications. Aim: This study reviews existing research into the relationship between Candida albicans and nipple and breast pain in breastfeeding women who have been diagnosed with mammary candidiasis; whether fluconazole is an effective treatment; and the presence of C. albicans in the human milk microbiome. Method: The author conducted three searches to investigate (a) breastfeeding-related pain and C. albicans; (b) the efficacy of fluconazole in breastfeeding-related pain; and (c) composition of the human milk mycobiome. These findings are critiqued and integrated in a narrative review. Results: There is little evidence to support the hypothesis that Candida spp, including C. albicans, in maternal milk or on the nipple-areolar complex causes the signs and symptoms popularly diagnosed as mammary candidiasis. There is no evidence that antifungal treatments are any more effective than the passage of time in women with these symptoms. Candida spp including C. albicans are commonly identified in healthy human milk and nipple-areolar complex mycobiomes. Discussion: Clinical breastfeeding support remains a research frontier. The human milk microbiome, which includes a mycobiome, interacts with the microbiomes of the infant mouth and nipple-areolar complex, including their mycobiomes, to form protective ecosystems. Topical or oral antifungals may disrupt immunoprotective microbial homeostasis. Unnecessary use contributes to the serious global problem of antifungal resistance. Conclusion: Antifungal treatment is rarely indicated and prolonged courses cannot be justified in breastfeeding women experiencing breast and nipple pain. Multiple strategies for stabilizing microbiome feedback loops when nipple and breast pain emerge are required, in order to avoid overtreatment of breastfeeding mothers and their infants with antifungal medications.

Download Full-text

Estimation of resistance force at steady-state sinkage for cylindrical wheel-typed lunar/planetary exploration rovers with function of push–pull locomotion

ROBOMECH Journal ◽

10.1186/s40648-020-00183-0 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Daisuke Fujiwara ◽

Naoki Tsujikawa ◽

Tetsuya Oshima ◽

Kojiro Iizuka

Keyword(s):

Steady State ◽

Estimation Method ◽

Planetary Exploration ◽

Experimental Result ◽

Resistance Force ◽

Estimation Model ◽

Loose Soil ◽

Key Factor ◽

The Relationship ◽

Resistance Forces

Abstract Planetary exploration rovers have required a high traveling performance to overcome obstacles such as loose soil and rocks. Push-pull locomotion rovers is a unique scheme, like an inchworm, and it has high traveling performance on loose soil. Push-pull locomotion uses the resistance force by keeping a locked-wheel related to the ground, whereas the conventional rotational traveling uses the shear force from loose soil. The locked-wheel is a key factor for traveling in the push-pull scheme. Understanding the sinking behavior and its resistance force is useful information for estimating the rover’s performance. Previous studies have reported the soil motion under the locked-wheel, the traction, and the traveling behavior of the rover. These studies were, however, limited to the investigation of the resistance force and amount of sinkage for the particular condition depending on the rover. Additionally, the locked-wheel sinks into the soil until it obtains the required force for supporting the other wheels’ motion. How the amount of sinkage and resistance forces are generated at different wheel sizes and mass of an individual wheel has remained unclear, and its estimation method hasn’t existed. This study, therefore, addresses the relationship between the sinkage and its resistance force, and we analyze and consider this relationship via the towing experiment and theoretical consideration. The results revealed that the sinkage reached a steady-state value and depended on the contact area and mass of each wheel, and the maximum resistance force also depends on this sinkage. Additionally, the estimation model did not capture the same trend as the experimental results when the wheel width changed, whereas, the model captured a relatively the same trend as the experimental result when the wheel mass and diameter changed.

Download Full-text

Antimicrobial Active Bioplastics Using Triangular Silver Nanoplate Integrated Polycaprolactone and Polylactic Acid Films

Materials ◽

10.3390/ma14051132 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1132

Author(s):

Eduardo Lanzagorta Garcia ◽

Olivia A. Attallah ◽

Marija Mojicevic ◽

Declan M Devine ◽

Margaret Brennan Fournet

Keyword(s):

Polylactic Acid ◽

Scale Up ◽

Composite Films ◽

Antimicrobial Properties ◽

Morphological Structure ◽

Antimicrobial Effect ◽

Solvent Casting ◽

Local Surface Plasmon Resonance ◽

Casting Technique ◽

Triangular Silver Nanoplates

An innovative antimicrobial technology for plastic surfaces is presented. We report the synthesis and scale-up of triangular silver nanoplates (TSNPs) and their integration into polycaprolactone (PCL) and polylactic acid (PLA) polymers through a solvent-casting technique. The TSNPs have a high geometric aspect ratio and strong local surface plasmon resonance (LSPR) response, which provides an effective tool for monitoring their integrity during processing and integration with the biodegradable plastics. An aqueous-based seed-mediated chemical method was used to synthesize the TSNPs, and characterisation was carried out using TEM and UV (Ultraviolet)-VIS (Visible) spectroscopy to measure LSPR profiles. The UV-VIS spectra of silver seeds and TSNPs exhibited characteristic peaks at 395 and 600 nm respectively. Synthesized TSNPs were coated with thiol-terminated polyethylene glycol (SH-PEG) and transferred into chloroform in order to effect compatibility with PCL and PLA. TSNP/PCL and TSNP/PLA composite films were prepared by solvent casting. The morphological structure, thermal, mechanical, and antimicrobial properties of the TSNP-incorporated composite films were evaluated. Results showed the TSNP-treated films had a rougher surface than the bare films. Insignificant changes in the thermal properties of TSNP-treated films compared to bare ones were also observed, which indicated the thermal stability of the composite films. The tensile strength and antimicrobial properties of the composite films were increased after TSNP incorporation. TSNP/PCL and TSNP/PLA films exhibited improved antimicrobial activity against Escherichia coli and Staphylococcus aureus with antimicrobial effect (AE) values ranging between 0.10 and 0.35. The obtained results and demonstrated TSNP production scalability validate the TSNP treated PCL and PLA films as a composite material with desirable antimicrobial effect for wide-ranging surface applications.

Download Full-text

Silver Nanoparticles Induce Neutrophil Extracellular Traps Via Activation of PAD and Neutrophil Elastase

Biomolecules ◽

10.3390/biom11020317 ◽

2021 ◽

Vol 11 (2) ◽

pp. 317

Author(s):

HanGoo Kang ◽

Jinwon Seo ◽

Eun-Jeong Yang ◽

In-Hong Choi

Keyword(s):

Silver Nanoparticles ◽

Neutrophil Elastase ◽

Mammalian Cells ◽

Antimicrobial Properties ◽

Neutrophil Extracellular Traps ◽

Arginine Deiminase ◽

Human Neutrophils ◽

Extracellular Traps ◽

Peptidyl Arginine Deiminase ◽

Key Factor

Silver nanoparticles (AgNPs) are widely used in various fields because of their antimicrobial properties. However, many studies have reported that AgNPs can be harmful to both microorganisms and humans. Reactive oxygen species (ROS) are a key factor of cytotoxicity of AgNPs in mammalian cells and an important factor in the immune reaction of neutrophils. The immune reactions of neutrophils include the expulsion of webs of DNA surrounded by histones and granular proteins. These webs of DNA are termed neutrophil extracellular traps (NETs). NETs allow neutrophils to catch and destroy pathogens in extracellular spaces. In this study, we investigated how AgNPs stimulate neutrophils, specifically focusing on NETs. Freshly isolated human neutrophils were treated with 5 or 100 nm AgNPs. The 5 nm AgNPs induced NET formation, but the 100 nm AgNPs did not. Subsequently, we investigated the mechanism of AgNP-induced NETs using known inhibitors related to NET formation. AgNP-induced NETs were dependent on ROS, peptidyl arginine deiminase, and neutrophil elastase. The result in this study indicates that treatment of 5 nm AgNPs induce NET formation through histone citrullination by peptidyl arginine deiminase and histone cleavage by neutrophil elastase.

Download Full-text

Mental imagery: pulling the plug on perceptualism

Philosophical Studies ◽

10.1007/s11098-021-01628-x ◽

2021 ◽

Author(s):

Dan Cavedon-Taylor

Keyword(s):

Mental Imagery ◽

Structural Features ◽

Predictive Processing ◽

Perceptual State ◽

Perceptual Disorders ◽

Whole Class ◽

The Relationship

AbstractWhat is the relationship between perception and mental imagery? I aim to eliminate an answer that I call perceptualism about mental imagery. Strong perceptualism, defended by Bence Nanay, predictive processing theorists, and several others, claims that imagery is a kind of perceptual state. Weak perceptualism, defended by M. G. F. Martin and Matthew Soteriou, claims that mental imagery is a representation of a perceptual state, a view sometimes called The Dependency Thesis. Strong perceptualism is to be rejected since it misclassifies imagery disorders and abnormalities as perceptual disorders and abnormalities. Weak Perceptualism is to be rejected since it gets wrong the aim and accuracy conditions of a whole class of mental imagery–projected mental imagery–and relies on an impoverished concept of perceptual states, ignoring certain of their structural features. Whatever the relationship between perception and imagery, the perceptualist has it wrong.

Download Full-text

Antimicrobial Activity of Curcumin in Nanoformulations: A Comprehensive Review

International Journal of Molecular Sciences ◽

10.3390/ijms22137130 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7130

Author(s):

Jeffersson Krishan Trigo-Gutierrez ◽

Yuliana Vega-Chacón ◽

Amanda Brandão Soares ◽

Ewerton Garcia de Oliveira Mima

Keyword(s):

Polymeric Nanoparticles ◽

Graphene Quantum Dots ◽

Antimicrobial Properties ◽

Antimicrobial Effect ◽

Clinical Scenarios ◽

Low Cytotoxicity ◽

Bacteria And Fungi ◽

Drug Resistant Strains

Curcumin (CUR) is a natural substance extracted from turmeric that has antimicrobial properties. Due to its ability to absorb light in the blue spectrum, CUR is also used as a photosensitizer (PS) in antimicrobial Photodynamic Therapy (aPDT). However, CUR is hydrophobic, unstable in solutions, and has low bioavailability, which hinders its clinical use. To circumvent these drawbacks, drug delivery systems (DDSs) have been used. In this review, we summarize the DDSs used to carry CUR and their antimicrobial effect against viruses, bacteria, and fungi, including drug-resistant strains and emergent pathogens such as SARS-CoV-2. The reviewed DDSs include colloidal (micelles, liposomes, nanoemulsions, cyclodextrins, chitosan, and other polymeric nanoparticles), metallic, and mesoporous particles, as well as graphene, quantum dots, and hybrid nanosystems such as films and hydrogels. Free (non-encapsulated) CUR and CUR loaded in DDSs have a broad-spectrum antimicrobial action when used alone or as a PS in aPDT. They also show low cytotoxicity, in vivo biocompatibility, and improved wound healing. Although there are several in vitro and some in vivo investigations describing the nanotechnological aspects and the potential antimicrobial application of CUR-loaded DDSs, clinical trials are not reported and further studies should translate this evidence to the clinical scenarios of infections.

Download Full-text

Gold Nanoparticles Synthesis and Antimicrobial Effect on Fibrous Materials

Nanomaterials ◽

10.3390/nano11051067 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1067

Author(s):

Behnaz Mehravani ◽

Ana Isabel Ribeiro ◽

Andrea Zille

Keyword(s):

Gold Nanoparticles ◽

Antimicrobial Properties ◽

Antimicrobial Effect ◽

Environmental Concerns ◽

Fibrous Materials ◽

Barrier Material ◽

Future Studies ◽

Textile Materials ◽

Promising Strategy ◽

Antimicrobial Materials

Depositing nanoparticles in textiles have been a promising strategy to achieve multifunctional materials. Particularly, antimicrobial properties are highly valuable due to the emergence of new pathogens and the spread of existing ones. Several methods have been used to functionalize textile materials with gold nanoparticles (AuNPs). Therefore, this review highlighted the most used methods for AuNPs preparation and the current studies on the topic in order to obtain AuNPs with suitable properties for antimicrobial applications and minimize the environmental concerns in their production. Reporting the detailed information on the functionalization of fabrics, yarns, and fibers with AuNPs by different methods to improve the antimicrobial properties was the central objective. The studies combining AuNPs and textile materials have opened valuable opportunities to develop antimicrobial materials for health and hygiene products, as infection control and barrier material, with improved properties. Future studies are needed to amplify the antimicrobial effect of AuNPs onto textiles and minimize the concerns related to the synthesis.

Download Full-text