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Open Biology Aug 2022Sea stars adhere strongly but temporarily to underwater substrata via the secretion of a blend of proteins, forming an adhesive footprint that they leave on the surface...
Sea stars adhere strongly but temporarily to underwater substrata via the secretion of a blend of proteins, forming an adhesive footprint that they leave on the surface after detachment. Their tube feet enclose a duo-gland adhesive system comprising two types of adhesive cells, contributing different layers of the footprint and de-adhesive cells. In this study, we characterized the catalogue of sea star footprint proteins (Sfps) in the species to gain insights in their potential function. We identified 16 Sfps and mapped their expression to type 1 and/or type 2 adhesive cells or to de-adhesive cells by double fluorescent hybridization. Based on their cellular expression pattern and their conserved functional domains, we propose that the identified Sfps serve different functions during attachment, with two Sfps coupling to the surface, six providing cohesive strength and the rest forming a binding matrix. Immunolabelling of footprints with antibodies directed against one protein of each category confirmed these roles. A de-adhesive gland cell-specific astacin-like proteinase presumably weakens the bond between the adhesive material and the tube foot surface during detachment. Overall, we provide a model for temporary adhesion in sea stars, including a comprehensive list of the proteins involved.
Topics: Adhesives; Animals; In Situ Hybridization, Fluorescence; Proteins; Starfish
PubMed: 35975651
DOI: 10.1098/rsob.220103 -
ACS Applied Materials & Interfaces Oct 2021The excellent adhesion of mussels under wet conditions has inspired the development of numerous catechol-based wet adhesives. Nevertheless, the performance of...
The excellent adhesion of mussels under wet conditions has inspired the development of numerous catechol-based wet adhesives. Nevertheless, the performance of catechol-based wet adhesive suffers from the sensitivity toward temperature, pH, or oxidation stimuli. Therefore, it is of great significance to develop non-catechol-based wet adhesives to fully recapitulate nature's dynamic function. Herein, a novel type of non-catechol-based wet adhesive is reported, which is readily formed by self-assembly of commercially available branched polyethylenimine and phosphotungstic acid in aqueous solution through the combination of electrostatic interaction and hydrogen bonding. This wet adhesive shows reversible, tunable, and strong adhesion on diverse substrates and further exhibits high efficacy in promoting biological wound healing. During the healing of the wound, the as-prepared wet adhesive also possesses inherent antimicrobial properties, thus avoiding inflammations and infections due to microorganism accumulation.
Topics: Adhesiveness; Adhesives; Animals; Anti-Bacterial Agents; Escherichia coli; Hemostatics; Hydrogen Bonding; Mice; Phosphoric Acids; Polyethyleneimine; Staphylococcal Skin Infections; Staphylococcus aureus; Static Electricity; Tungsten Compounds; Water; Wound Healing
PubMed: 34565147
DOI: 10.1021/acsami.1c14231 -
Soft Matter Nov 2016The adhesion of two materials in the presence of water is greatly impeded by a boundary layer of water between the adhesive and the adherend, resulting in adhesive... (Review)
Review
The adhesion of two materials in the presence of water is greatly impeded by a boundary layer of water between the adhesive and the adherend, resulting in adhesive failure of most synthetic adhesives; however, life evolved first in water and there are many aquatic organisms that have to overcome this impediment to underwater adhesion. For example, multicellular aquatic organisms like the mussel, sandcastle worm and the caddisfly larva employ well-studied adhesive mechanisms for sticking in the presence of water. Unicellular organisms such as bacteria also make use of various means for attaching to surfaces, within similar environmental conditions. Prominent among them is the aquatic bacteria, Caulobacter crescentus which utilizes a unique adhesive secretion, the holdfast, to adhere strongly in the presence of water. Here we review the attachment mechanisms of some multicellular aquatic organisms and compare the similarities and differences in the composition and structure of the C. crescentus holdfast, which holds promise as a potential source for bio-inspired synthetic underwater adhesives with prospective applications in medicine, engineering and biomimetics.
Topics: Adhesives; Animals; Bacterial Adhesion; Caulobacter crescentus; Insecta; Polysaccharides, Bacterial; Prospective Studies; Water; Water Microbiology
PubMed: 27812588
DOI: 10.1039/c6sm02163h -
Journal of the Mechanical Behavior of... Jun 2018Hydroxyethyl-methacrylate (HEMA) is still widely used in simplified adhesives. Indeed, several shortcomings occur with this monomer, such as water uptake and formation...
OBJECTIVES
Hydroxyethyl-methacrylate (HEMA) is still widely used in simplified adhesives. Indeed, several shortcomings occur with this monomer, such as water uptake and formation of linear polymers. This study aimed to compare the effects of HEMA replacement by glycerol-dimethacrylate (GDMA) on selected physicochemical properties and bonding performance of simplified model adhesives.
MATERIALS AND METHODS
Experimental simplified etch-and-rinse and self-etch adhesives were formulated containing 20 wt% HEMA or GDMA. Three-point bending test was used to obtain the elastic modulus of bar-shaped specimens, and water sorption and solubility were attained by ISO-4049 (ISO, 2009) method. Degree of conversion was surveyed by Micro-Raman spectroscopy, and microtensile bond strength was tested after 24 h or 6 months simulated pulpal pressure aging. Statistical analysis was realized with two-way ANOVA and Tukey's test (p < 0.05).
RESULTS
GDMA promoted higher elastic modulus to the self-etch adhesive, and GDMA-containing etch-and-rinse adhesive achieved overall lower water sorption and solubility. The degree of conversion was statistically higher for GDMA adhesives than for HEMA etch-and-rinse one. All bond strengths dropped significantly after aging, except that of GDMA self-etch adhesive. The nanoleakage was higher and gaps were found in the interface of HEMA-containing adhesives, which were less present in GDMA equivalents.
CONCLUSIONS
GDMA is a feasible hydrophilic dimethacrylate monomer to replace HEMA in simplified adhesives, thereby providing better polymerization, mechanical properties and dentin adhesion as well as lower water uptake and solubility.
Topics: Adhesives; Glycerol; Hydrophobic and Hydrophilic Interactions; Methacrylates; Tensile Strength
PubMed: 29574280
DOI: 10.1016/j.jmbbm.2018.03.022 -
Materials Horizons Mar 2021Mussel foot proteins (Mfps) show strong adhesion to underwater substrates, making mussels tightly cling to reefs to withstand the sea current. Therefore, Mfps-inspired...
Mussel foot proteins (Mfps) show strong adhesion to underwater substrates, making mussels tightly cling to reefs to withstand the sea current. Therefore, Mfps-inspired tissue adhesives have aroused much research interest, but tough underwater biological tissue adhesion is still a great challenge. Herein, we report a tough and reversible wet tissue-selective adhesive hydrogel made of poly(acrylic acid-co-catechol) and chitosan (CS). It provides negatively charged -COO, positively charged -NH, catechol group and hydrophobic alkyl chain, resemble amino acids, catechol and hydrophobic units in Mfps. Due to the covalent/electrostatic attraction/π-π/cationic-π/hydrogen bonding, in addition to the hydrophobic interaction from the long hydrophobic alkyl chain of the catechol derivative, the hydrogel has a high cohesion strength and toughness, i.e., tensile stress, fracture strain and fracture toughness of ∼0.57 MPa, 2510% and 6620 J m, respectively. As a tissue adhesive, its adhesion bonding to the porcine skin surface is so strong that its adhesion strength is almost equal to the tearing strength of the hydrogel. The 180-degree peeling adhesion energy of the hydrogel to blood-wetted porcine skin is notably ∼1010 J m. It can tightly and seamlessly adhere to the porcine small intestine, and has a bursting pressure of up to 520 mmHg. The hydrogel can be handily debonded from the porcine skin surface in the presence of aqueous solution at pH 8.0, and its adhesiveness is reversible for at least 20 cycles. It is supposed that the synergistic interactions of the adhesive catechol group, displacement of water on the wet skin surface by the positively charged -NH groups of CS and the water-repelling potential of the hydrophobic unit of the catechol derivative, the protection of the catechol group from oxidation into a less adhesive quinone group, and the energy dissipation capacity of the mechanically tough hydrogel contribute to the strong and repeatable wet tissue adhesion.
Topics: Adhesiveness; Adhesives; Animals; Bivalvia; Hydrogels; Swine; Tissue Adhesives
PubMed: 34821330
DOI: 10.1039/d0mh01231a -
Proceedings. Biological Sciences Jun 2021Among the most specialized integumentary outgrowths in amniotes are the adhesive, scale-like scansors and lamellae on the digits of anoles and geckos. Less well-known...
Among the most specialized integumentary outgrowths in amniotes are the adhesive, scale-like scansors and lamellae on the digits of anoles and geckos. Less well-known are adhesive tail pads exhibited by 21 gecko genera. While described over 120 years ago, no studies have quantified their possible adhesive function or described their embryonic development. Here, we characterize adult and embryonic morphology and adhesive performance of crested gecko () tail pads. Additionally, we use embryonic data to test whether tail pads are serial homologues to toe pads. External morphology and histology of . tail pads are largely similar to tail pads of closely related geckos. Functionally, . tail pads exhibit impressive adhesive ability, hypothetically capable of holding up to five times their own mass. Tail pads develop at approximately the same time during embryogenesis as toe pads. Further, tail pads exhibit similar developmental patterns to toe pads, which are markedly different from non-adhesive gecko toes and tails. Our data provide support for the serial homology of adhesive tail pads with toe pads.
Topics: Adhesiveness; Adhesives; Animals; Biomechanical Phenomena; Biophysics; Lizards; Toes
PubMed: 34130507
DOI: 10.1098/rspb.2021.0650 -
Biofabrication Jun 2023Adhesive hydrogels possess great potential to be explored as tissue adhesives, surgical sealants, and hemostats. However, it has been a great challenge to develop...
Adhesive hydrogels possess great potential to be explored as tissue adhesives, surgical sealants, and hemostats. However, it has been a great challenge to develop hydrogels that can function rapidly and controllably on wet, dynamic biological tissues. Inspired by polyphenol chemistry, we introduce a coacervation-triggered shaping strategy that enables the hierarchical assembly of recombinant human collagen (RHC) and tannic acid (TA). The conformation of the RHC and TA aggregates is controlled to evolve from granular to web-like states, accompanied by the significant enhancement of mechanical and adhesion performance. The coacervation and assembly process is driven by intermolecular interactions, especially hydrogen bonding between RHC and TA. Benefitting from the multifaceted nature of polyphenol chemistry, the hierarchically assembled hydrogels revealed excellent properties as surgical sealing materials, including fast gelation time (within 10 s), clotting time (within 60 s), ultrastretchability (strain >10 000%), and tough adhesion (adhesive strength >250 kPa).experiments demonstrated complete sealing of severely leaking heart and liver tissues with the assistance offormed hydrogels during 7 d of follow-up. This work presents a highly promising hydrogel-based surgical sealant in wet and dynamic biological environments for future biomedical applications.
Topics: Humans; Hydrogels; Adhesives; Polyphenols
PubMed: 37285837
DOI: 10.1088/1758-5090/acdc55 -
ACS Applied Materials & Interfaces Dec 2022Conductive hydrogels have attracted extensive interest owing to its potential in soft robotics, electronic skin, and human monitoring. However, insufficient mechanical...
Conductive hydrogels have attracted extensive interest owing to its potential in soft robotics, electronic skin, and human monitoring. However, insufficient mechanical properties, lower adhesivity, and unsatisfactory conductivity seriously hinder potential applications in this emerging field. Herein, a highly elastic conductive hydrogel with a combination of favorable mechanical properties, self-adhesiveness, and excellent electrical performance was achieved by the synergistic effect of aminated lignin (AL), polydopamine (PDA), polyacrylamide (PAM) chains, and biomass carbon aerogel (C-SPF). In detail, AL was applied to induce slow oxidative polymerization of DA for preparing the sticky hydrogel containing PDA. Then, C-SPF carbon aerogel was used as a matrix to construct a dual-network structured composite hydrogel by combining with the hydrogels derived from PDA, AL, and PAM. The as-prepared conductive hydrogel displayed excellent mechanical performance, strong adhesive strength, and repeatable adhesivity. The prepared hydrogel-based pressure sensor possessed fast response (0.6 s loading and 0.8 s unloading stress time), high response (maximum RCR = 1.8 × 10), wide working pressure range (from 0 to 240.0 kPa), and excellent durability (stable 500 compression cycles with 30% deformation). In addition, the prepared sensor also displayed ultrahigh sensitivity (170 kPa), which was near 4 orders of magnitude higher than the conventional lignin-modified PAM hydrogels. The multiple interactions between hydrogel components and the mechanical properties of hydrogel were also verified by molecular dynamics investigation. Moreover, the excellent cytocompatibility and antibacterial activity of this composite hydrogel ensured high potential in various applications such as human/machine interaction, artificial intelligence, personal healthcare, and wearable devices.
Topics: Humans; Lignin; Adhesives; Dopamine; Carbon; Resin Cements; Artificial Intelligence
PubMed: 36413754
DOI: 10.1021/acsami.2c12914 -
Therapeutic Delivery 2016Transdermal drug delivery systems (TDDS) are employed for the delivery of drugs across skin into the systemic circulation. Pressure-sensitive adhesive (PSA) is one of... (Review)
Review
Transdermal drug delivery systems (TDDS) are employed for the delivery of drugs across skin into the systemic circulation. Pressure-sensitive adhesive (PSA) is one of the most critical components used in a TDDS. The primary function of PSA is to help in adhesion of patch to skin, but more importantly it acts as a matrix for the drug and other excipients. Hence, apart from adhesion of the patch, PSA also affects other critical quality attributes of the TDDS such as drug delivery, flux through skin and physical and chemical stability of the finished product. This review article provides a summary of the adhesives used in various types of TDDS. In particular, this review will cover the design types of TDDS, categories of PSAs and their evaluation and regulatory aspects.
Topics: Adhesives; Administration, Cutaneous; Drug Delivery Systems; Drug Design; Excipients; Humans; Pharmaceutical Preparations; Pressure; Skin Absorption; Transdermal Patch
PubMed: 26652621
DOI: 10.4155/tde.15.87 -
Ultrasonics Sonochemistry Sep 2022Poor adhesion of nickel surface limits its further application in the aerospace field. In this study, plasma modification was conducted on the surface of the nickel...
Poor adhesion of nickel surface limits its further application in the aerospace field. In this study, plasma modification was conducted on the surface of the nickel plate pretreated by sandblasting, and then ultrasonic vibration was applied during the adhesively bonding process of the CFRP(Carbon fibre-reinforced polymer)/Ni joints. The bonding strength of the joints was increased by 65%. The adherend surface and the bonding interface were analyzed from microstructure, element distribution and chemical bonding to study the strengthening mechanism. By the sandblasting, irregular pits were formed on the nickel surface, effectively increasing the surface roughness. The plasma modification could introduce active functional groups including hydroxyl, amino and carbonyl on the nickel surface, which improved the surface wettability macroscopically. However, at a microscopic level, the adhesive with high viscosity and poor fluidity did not form a compact interface with the nickel. The ultrasonic application could promote the filling of the adhesive in irregular micro-scale pits on the surface, thereby strengthening the mechanical anchoring effect. Furthermore, the ultrasonic application produced dynamic impingement at the interface, enhancing the contact between the adhesive and the nickel plate. The adhesive molecules could fully collide and react with the active functional groups introduced on the nickel surface to form more chemical bonds, thus effectively improving the bonding strength of the CFRP/Ni joints.
Topics: Adhesives; Carbon Fiber; Materials Testing; Nickel; Plastics; Ultrasonic Waves
PubMed: 36007330
DOI: 10.1016/j.ultsonch.2022.106126