scholarly journals Influence of substrate modulus on gecko adhesion

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Mena R. Klittich ◽  
Michael C. Wilson ◽  
Craig Bernard ◽  
Rochelle M. Rodrigo ◽  
Austin J. Keith ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Wearable Electronics ◽  
Natural Habitats ◽  
Gekko Gecko ◽  
Dry Adhesion ◽  
Adhesion System ◽  
Synthetic Adhesives ◽  
Influence Of Substrate ◽  
Gecko Adhesion ◽  
First Time

Abstract The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

scholarly journals Passively stuck: death does not affect gecko adhesion strength

2014 ◽  
Vol 10 (12) ◽  
pp. 20140701 ◽  
Author(s):  
William J. Stewart ◽  
Timothy E. Higham
Keyword(s):  
Active Control ◽  
Adhesive Force ◽  
Vertical Surface ◽  
Gekko Gecko ◽  
Novel Device ◽  
Pulling Forces ◽  
Strong Adhesion ◽  
Kinematic Analyses ◽  
Gecko Adhesion ◽  
First Time

Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos ( Gekko gecko ) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control.

scholarly journals Role of contact electrification and electrostatic interactions in gecko adhesion

2014 ◽  
Vol 11 (98) ◽  
pp. 20140371 ◽  
Author(s):  
Hadi Izadi ◽  
Katherine M. E. Stewart ◽  
Alexander Penlidis
Keyword(s):  
Electrostatic Interactions ◽  
Van Der Waals ◽  
Adhesion Forces ◽  
Intimate Contact ◽  
Contact Electrification ◽  
Dry Adhesion ◽  
Dry Adhesives ◽  
Gecko Adhesion ◽  
First Time

Geckos, which are capable of walking on walls and hanging from ceilings with the help of micro-/nano-scale hierarchical fibrils (setae) on their toe pads, have become the main prototype in the design and fabrication of fibrillar dry adhesives. As the unique fibrillar feature of the toe pads of geckos allows them to develop an intimate contact with the substrate the animal is walking on or clinging to, it is expected that the toe setae exchange significant numbers of electric charges with the contacted substrate via the contact electrification (CE) phenomenon. Even so, the possibility of the occurrence of CE and the contribution of the resulting electrostatic interactions to the dry adhesion of geckos have been overlooked for several decades. In this study, by measuring the magnitude of the electric charges, together with the adhesion forces, that gecko foot pads develop in contact with different materials, we have clarified for the first time that CE does contribute effectively to gecko adhesion. More importantly, we have demonstrated that it is the CE-driven electrostatic interactions which dictate the strength of gecko adhesion, and not the van der Waals or capillary forces which are conventionally considered as the main source of gecko adhesion.

scholarly journals A Physical Model Approach to Gecko Adhesion Opportunity and Constraint: How Rough Could It Be?

2019 ◽  
Vol 59 (1) ◽  
pp. 203-213 ◽  
Author(s):  
Peter H Niewiarowski ◽  
Ali Dhinojwala ◽  
Austin M Garner
Keyword(s):  
Adhesive System ◽  
Intermolecular Forces ◽  
Design Parameters ◽  
Substrate Roughness ◽  
Natural Habitats ◽  
Synthetic Adhesives ◽  
Ecological Methods ◽  
And Function ◽  
Gecko Adhesion ◽  
Free Ranging

AbstractIt has been nearly 20 years since Autumn and colleagues established the central role of van der Waals intermolecular forces in how geckos stick. Much has been discovered about the structure and function of fibrillar adhesives in geckos and other taxa, and substantial success has been achieved in translating natural models into bioinspired synthetic adhesives. Nevertheless, synthetics still cannot match the multidimensional performance observed in the natural gecko system that is simultaneously robust to dirt and water, resilient over thousands of cycles, and purportedly competent on surfaces that are rough at drastically different length scales. Apparent insensitivity of adhesion to variability in roughness is particularly interesting from both a theoretical and applied perspective. Progress on understanding the extent to which and the basis of how the gecko adhesive system is robust to variation in roughness is impeded by the complexity of quantifying roughness of natural surfaces and a dearth of data on free-ranging gecko substrate use. Here we review the main challenges in characterizing rough surfaces as they relate to collecting relevant estimates of variation in gecko adhesive performance across different substrates in their natural habitats. In response to these challenges, we propose a practical protocol (borrowing from thermal biophysical ecological methods) that will enable researchers to design detailed studies of structure–function relationships of the gecko fibrillar system. Employing such an approach will help provide specific hypotheses about how adhesive pad structure translates into a capacity for robust gecko adhesion across large variation in substrate roughness. Preliminary data we present on this approach suggest its promise in advancing the study of how geckos deal with roughness variation. We argue and outline how such data can help advance development of design parameters to improve bioinspired adhesives based on the gecko fibrillar system.

scholarly journals Hexapod Assassins’ Potion: Venom Composition and Bioactivity from the Eurasian Assassin Bug Rhynocoris iracundus

Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 819
Author(s):  
Nicolai Rügen ◽  
Timothy P. Jenkins ◽  
Natalie Wielsch ◽  
Heiko Vogel ◽  
Benjamin-Florian Hempel ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Galleria Mellonella ◽  
Systemic Reactions ◽  
Venom Composition ◽  
Assassin Bug ◽  
Molecular Components ◽  
First Time ◽  
Tissue Digestion

Assassin bug venoms are potent and exert diverse biological functions, making them potential biomedical goldmines. Besides feeding functions on arthropods, assassin bugs also use their venom for defense purposes causing localized and systemic reactions in vertebrates. However, assassin bug venoms remain poorly characterized. We collected the venom from the assassin bug Rhynocoris iracundus and investigated its composition and bioactivity in vitro and in vivo. It caused lysis of murine neuroblastoma, hepatoma cells, and healthy murine myoblasts. We demonstrated, for the first time, that assassin bug venom induces neurolysis and suggest that it counteracts paralysis locally via the destruction of neural networks, contributing to tissue digestion. Furthermore, the venom caused paralysis and melanization of Galleria mellonella larvae and pupae, whilst also possessing specific antibacterial activity against Escherichia coli, but not Listeria grayi and Pseudomonas aeruginosa. A combinatorial proteo-transcriptomic approach was performed to identify potential toxins responsible for the observed effects. We identified neurotoxic Ptu1, an inhibitory cystin knot (ICK) toxin homologous to ω-conotoxins from cone snails, cytolytic redulysins homologous to trialysins from hematophagous kissing bugs, and pore-forming hemolysins. Additionally, chitinases and kininogens were found and may be responsible for insecticidal and cytolytic activities. We demonstrate the multifunctionality and complexity of assassin bug venom, which renders its molecular components interesting for potential biomedical applications.

scholarly journals Raman spectroscopic detection of interleukin-10 and angiotensin converting enzyme

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Shuo Zhang ◽  
Frederieke A. M. van der Mee ◽  
Roel J. Erckens ◽  
Carroll A. B. Webers ◽  
Tos T. J. M. Berendschot
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Biomedical Applications ◽  
Interleukin 10 ◽  
Spectral Features ◽  
Converting Enzyme ◽  
Raman Spectroscopic ◽  
Non Invasive ◽  
Confocal Raman ◽  
First Time ◽  
Enzyme Characteristic

AbstractIn this report we present a confocal Raman system to identify the unique spectral features of two proteins, Interleukin-10 and Angiotensin Converting Enzyme. Characteristic Raman spectra were successfully acquired and identified for the first time to our knowledge, showing the potential of Raman spectroscopy as a non-invasive investigation tool for biomedical applications.

scholarly journals Phosphatidylserine-Gold Nanoparticles (PS-AuNP) Induce Prostate and Breast Cancer Cell Apoptosis

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1094
Author(s):  
Allan Radaic ◽  
Nam E. Joo ◽  
Soo-Hwan Jeong ◽  
Seong-II Yoo ◽  
Nicholas Kotov ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gold Nanoparticles ◽  
Biomedical Applications ◽  
Therapeutic Potential ◽  
Control Treatment ◽  
Track Record ◽  
Males And Females ◽  
Breast And Prostate Cancer ◽  
First Time

Prostate and breast cancer are the current leading causes of new cancer cases in males and females, respectively. Phosphatidylserine (PS) is an essential lipid that mediates macrophage efferocytosis and is dysregulated in tumors. Therefore, developing therapies that selectively restore PS may be a potential therapeutic approach for carcinogenesis. Among the nanomedicine strategies for delivering PS, biocompatible gold nanoparticles (AuNPs) have an extensive track record in biomedical applications. In this study, we synthesized biomimetic phosphatidylserine-caped gold nanoparticles (PS-AuNPs) and tested their anticancer potential in breast and prostate cancer cells in vitro. We found that both cell lines exhibited changes in cell morphology indicative of apoptosis. After evaluating for histone-associated DNA fragments, a hallmark of apoptosis, we found significant increases in DNA fragmentation upon PS-AuNP treatment compared to the control treatment. These findings demonstrate the use of phosphatidylserine coupled with gold nanoparticles as a potential treatment for prostate and breast cancer. To the best of our knowledge, this is the first time that a phosphatidylserine-capped AuNP has been examined for its therapeutic potential in cancer therapy.

Novel Baddeleyite-Based Zirconia Ceramics for Biomedical Applications

2017 ◽  
Vol 13 ◽  
pp. 9-14
Author(s):  
Alexander I. Tyurin ◽  
Andrey O. Zhigachev ◽  
Alexey V. Umrikhin ◽  
Vyacheslav V. Rodaev ◽  
Tatyana S. Pirozhkova
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tetragonal Phase ◽  
Biomedical Applications ◽  
Zirconia Ceramics ◽  
Engineering Ceramics ◽  
Synthesis Conditions ◽  
Microstructure And Mechanical Properties ◽  
First Time

For the first time nanostructured engineering ceramics were prepared from natural zirconia mineral (baddeleyite) with CaO as a tetragonal phase stabilizer. The effect of synthesis conditions on microstructure and mechanical properties of the baddeleyite-based ceramics is reported, furthermore, the effect of calcia content on hardness and fracture toughness is studied. Optimal calcia concentration and synthesis conditions are found, corresponding hardness and fracture toughness values are 10,8 GPa and 13,3 MPa×m1/2. The reported mechanical properties are comparable to those typically reported for yttria-stabilized engineering zirconia ceramics, prepared from chemically synthesized zirconia.

scholarly journals Bio-inspired silver selenide nano-chalcogens using aqueous extract of Melilotus officinalis with biological activities

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Seyedeh Zahra Mirzaei ◽  
Hamed Esmaeil Lashgarian ◽  
Maryam Karkhane ◽  
Kiana Shahzamani ◽  
Alaa Kamil Alhameedawi ◽  
...  
Keyword(s):  
Aqueous Extract ◽  
Biomedical Applications ◽  
Size Range ◽  
Biological Activities ◽  
Spherical Shape ◽  
Silver Selenide ◽  
Melilotus Officinalis ◽  
Uv Visible ◽  
Dpph Scavenging ◽  
First Time

AbstractFor the first time, an aqueous extract of Melilotus officinalis was used to synthesize bimetallic silver selenide chalcogenide nanostructures (Ag2Se-NCs). The formation of NCs was confirmed and characterized by UV–visible and FTIR spectroscopy, SEM and TEM imaging, XRD and EDX crystallography, zeta potential (ZP) and size distribution (DLS). The bioactivities of biosynthesized Ag2Se-NCs, such as antibacterial, antibiofilm, antioxidant and cytotoxicity potentials, were then examined. Bio-based Ag2Se-NCs were successfully synthesized with mostly spherical shape in the size range of 20–40 nm. Additionally, the MIC and MBC values of Ag2Se-NCs against β-lactam-resistant Pseudomonas aeruginosa (ATCC 27853) were 3.12 and 50 µg/ml, respectively. The DPPH scavenging potential of Ag2Se-NCs in terms of IC50 was estimated to be 58.52. Green-synthesized Ag2Se-NCs have been shown to have promising benefits and could be used for biomedical applications. Although the findings indicate promising bioactivity of Ag2Se-NCs synthesized by M. officinalis extract (MO), more studies are required to clarify the comprehensive mechanistic biological activities.

scholarly journals Assessment of the state of populations of protected plants species in Russko-Polyansky municipal district of Omsk region

2021 ◽  
pp. 158-170
Author(s):  
Natalya V. Plikina ◽  
◽  
Andrey N. Efremov ◽  
Galina V. Samoilova ◽  
◽  
...  
Keyword(s):  
Regional Level ◽  
Natural Area ◽  
Protected Species ◽  
Natural Habitats ◽  
Municipal District ◽  
Ephedra Distachya ◽  
The Status ◽  
Protected Natural Area ◽  
Protected Plants ◽  
First Time

The results of monitoring the populations of protected plant species of the Omsk region in the territories of Russko-Polyansky municipal district are presented. During the research 210 cenopopulations of 32 of protected plants species were found in total. The locations of 20 protected species at the regional level were identified at the studied district for the first time: Adonis villosa, A. volgensis, Allium clathratum, Alyssum lenense, Astragalus buchtormensis, A. stenoceras, Dianthus ramosissimus, Ephedra distachya, Fritillaria meleagroides, Hedysarum gmelinii, Iris halophila, I. humilis, Linum perenne, Orostachys spinosa, Puccinellia gigantea, Ranunculus polyrhizos, Stipa lessingiana, Tanacetum millefolium, Tulipa patens, Valeriana tuberose. Two species (Stipa pennata, S. zalesskii) have considered as federal protected objects. Three sites were identified where the maximum number of protected species in natural habitats is concentrated, one of them has now received the status of a specially protected natural area of local and regional significance.

scholarly journals Ectoparasites of the bats from karst caves of the nature reserve «Ichalkovsky Bor» (Nizhny Novgorod Region)

2018 ◽  
Vol 7 (4) ◽  
pp. 122-126
Author(s):  
Galina Anatolievna Fadeeva ◽  
Elena Evgenievna Boryakova
Keyword(s):  
Natural Habitats ◽  
Karst Caves ◽  
Central Russia ◽  
The Family ◽  
Volga Upland ◽  
The Stability ◽  
The One ◽  
Parasitic Mites ◽  
First Time

The fauna of parasitic mites of bats from the karst caves in the region of the Volga Upland was studied in 2004-2005. Six species of bats such as Daubentons water bat, Brandts bat, whiskered bat, pond bat, northern bat and long-eared bat were examined. 18 species of arthropods were detected, among them there are gamasid mites (10 species) and harvest mites (2 species). Leptotrombidium russicum (Oud., 1902) and Myotrombicula sp. were found for the first time in Central Russia. Spinturnix acuminatus (Koch, 1836), Steatonyssus spinosus (Willmann, 1936), Steatonyssus periblepharus (Kolenati, 1858), Macronyssus flavus (Kolenati, 1856) turned out to be the main group of parasites in this study. As for the insects flies of the family Nycteribiidae and fleas of the family Ischnopsyllidae were found. The cluster analysis of ectoparasite fauna has showed that they are more or less evenly distributed among all members of mixed colonies of bats, while there is no violation of specificity in the choice of hosts. Low values of the Berger-Parker index marked a lack of competition between species, which indicates the stability of parasitic communities formed on bats in mixed colonies and in natural habitats. This fact indicates a complex relationship between the parasites in the community on the one hand, and long-term existence of the community on the other hand. This, in its turn, shows that in long-evolving communities competitive relationships between parasites are obliterated, which gives them stability. Herewith the bat colony is used as an integral whole, although some parasitic species prefer certain types of hosts.

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