SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Adhesives

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Cyanoacrylate has been used as a commercial tissue adhesive. Recently, ethyl 2-cyanoacrylate has been suggested for the fixation of onlay autogenous bone graft. However, ethyl 2-cyanoacrylate must be biocompatible with bone tissue. This study evaluated the cytotoxicity of cyanoacrylate adhesives using a direct contact assay on human oral osteoblast cells.

Concepts: Bone, Cell, Cytotoxicity, Bone morphogenetic protein, Adhesive, Bone grafting, Adhesives, Cyanoacrylate

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BACKGROUND: Pilonidal sinus is a common condition often managed with invasive surgery associated with a significant morbidity and often a prolonged recovery time. Fibrin glue has been used in our institution as an alternative to conventional surgery. The purpose of this study was to perform a service evaluation of patient satisfaction and recovery following fibrin glue treatment for pilonidal sinus. METHODS: All pilonidal glue procedures for a single surgeon were identified from theatre and consultant diary records from March 2007 to September 2011. A questionnaire was sent by post to all patients. Patient satisfaction, time to return to normal activities, the need for further procedures and whether they would recommend a glue procedure to a friend were evaluated. RESULTS: Ninety-three patients were identified, accounting for a total of 119 glue procedures and 57/93 responses were received (61 %). The median age of respondents was 26 (17-70) years. Seventy-nine per cent (n = 45) were satisfied, pleased or very pleased with the result of their procedure. Fifty-four per cent (n = 31) were back to normal activities within a week with a further 17 % (n = 10) back to normal activities within 2 weeks. Seventy-four per cent (n = 42) required no further treatment. Of the 15 patients requiring a further procedure, 3 went on to have a repeat glue treatment which resulted in complete healing. Eighty-two per cent (n = 47) would recommend a glue procedure to a friend. CONCLUSIONS: Fibrin gluing for pilonidal sinus should be considered as first-line treatment for most pilonidal sinuses. It has a high level of patient satisfaction and allows a rapid return to normal activities in this group of patients of working age.

Concepts: Patient, Hospital, Surgery, Physician, Pilonidal cyst, Adhesive, Integers, Adhesives

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ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Adhesives for the restoration of non-carious cervical lesions: a systematic review. Chee B, Rickman LJ, Satterthwaite JD. J Dent 2012;40(6):443-52. Epub 2012 Feb 18. REVIEWER: David G. Pendrys, DDS, PhD PURPOSE/QUESTION: The purpose of this systematic review was to assess the effectiveness of currently available resin-based adhesive systems SOURCE OF FUNDING: Information not available TYPE OF STUDY/DESIGN: Systematic review LEVEL OF EVIDENCE: Level 2: Limited-quality, patient-oriented evidence STRENGTH OF RECOMMENDATION GRADE: Grade B: Inconsistent or limited-quality patient-oriented evidence.

Concepts: Evaluation, Evidence-based medicine, Review, Accept, Book review, Adhesive, Bibliographic database, Adhesives

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We have prepared composites of polyvinyl acetate (PVAc) reinforced with solution exfoliated graphene. We observe a 50% increase in stiffness and a 100% increase in tensile strength on addition of 0.1vol% graphene compared to the pristine polymer. As PVAc is commonly used commercially as a glue, we have tested such composites as adhesives. The adhesive strength and toughness of the composites were up to 4 and 7 times higher, respectively, than the pristine polymer.

Concepts: Acetic acid, Liquid, Epoxy, Adhesive, Polyvinyl acetate, Adhesives, Ethylene-vinyl acetate, Wood glue

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Frogs are well-known to capture elusive prey with their protrusible and adhesive tongues. However, the adhesive performance of frog tongues and the mechanism of the contact formation with the prey item remain unknown. Here we measured for the first time adhesive forces and tongue contact areas in living individuals of a horned frog (Ceratophrys sp.) against glass. We found that Ceratophrys sp. generates adhesive forces well beyond its own body weight. Surprisingly, we found that the tongues adhered stronger in feeding trials in which the coverage of the tongue contact area with mucus was relatively low. Thus, besides the presence of mucus, other features of the frog tongue (surface profile, material properties) are important to generate sufficient adhesive forces. Overall, the experimental data shows that frog tongues can be best compared to pressure sensitive adhesives (PSAs) that are of common technical use as adhesive tapes or labels.

Concepts: Mass, Force, Materials science, Adhesion, Adhesive, Frog, Adhesives, Pressure sensitive adhesive

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Over 130 y have passed since Charles Darwin first discovered that the adventitious roots of English ivy (Hedera helix) exude a yellowish mucilage that promotes the capacity of this plant to climb vertical surfaces. Unfortunately, little progress has been made in elucidating the adhesion mechanisms underlying this high-strength adhesive. In the previous studies, spherical nanoparticles were observed in the viscous exudate. Here we show that these nanoparticles are predominantly composed of arabinogalactan proteins (AGPs), a superfamily of hydroxyproline-rich glycoproteins present in the extracellular spaces of plant cells. The spheroidal shape of the AGP-rich ivy nanoparticles results in a low viscosity of the ivy adhesive, and thus a favorable wetting behavior on the surface of substrates. Meanwhile, calcium-driven electrostatic interactions among carboxyl groups of the AGPs and the pectic acids give rise to the cross-linking of the exuded adhesive substances, favor subsequent curing (hardening) via formation of an adhesive film, and eventually promote the generation of mechanical interlocking between the adventitious roots of English ivy and the surface of substrates. Inspired by these molecular events, a reconstructed ivy-mimetic adhesive composite was developed by integrating purified AGP-rich ivy nanoparticles with pectic polysaccharides and calcium ions. Information gained from the subsequent tensile tests, in turn, substantiated the proposed adhesion mechanisms underlying the ivy-derived adhesive. Given that AGPs and pectic polysaccharides are also observed in bioadhesives exuded by other climbing plants, the adhesion mechanisms revealed by English ivy may forward the progress toward understanding the general principles underlying diverse botanic adhesives.

Concepts: Cell wall, Viscosity, Liquid, Adhesive, Adhesives, Transudate, Ivy, Hedera helix

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Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m(-2)) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule.

Concepts: Liquid, Adhesion, Adhesive, Animal glue, Adhesives

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Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at -2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives.

Concepts: Present, Time, Liquid, Materials science, Elastomer, Adhesive, Adhesives, Bioadhesives

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Currently approved surgical tissue glues do not satisfy the requirements for ideal bioadhesives due to limited adhesion in wet conditions and severe cytotoxicity. Herein, we report a new light-activated, mussel protein-based bioadhesive (LAMBA) inspired by mussel adhesion and insect dityrosine crosslinking chemistry. LAMBA exhibited substantially stronger bulk wet tissue adhesion than commercially available fibrin glue and good biocompatibility in both in vitro and in vivo studies. Besides, the easily tunable, light-activated crosslinking enabled an effective on-demand wound closure and facilitated wound healing. Based on these outstanding properties, LAMBA holds great potential as an ideal surgical tissue glue for diverse medical applications, including sutureless wound closures of skin and internal organs.

Concepts: Cell, Blood, Wound healing, Surgery, Skin, Adhesive, Adhesives, Bioadhesives