Abstract The existing surgical adhesives are not ideal for wet tissue adhesion required in many surgeries such as those for internal organs. Developing surgical adhesives with strong wet tissue ...adhesion, controlled degradability and mechanical properties, and excellent biocompatibility has been a significant challenge. Herein, learning from nature, we report a one-step synthesis of a family of injectable citrate-based mussel-inspired bioadhesives (iCMBAs) for surgical use. Within the formulations investigated, iCMBAs showed 2.5–8.0 folds stronger wet tissue adhesion strength over the clinically used fibrin glue, demonstrated controlled degradability and tissue-like elastomeric mechanical properties, and exhibited excellent cyto/tissue-compatibility both in vitro and in vivo. iCMBAs were able to stop bleeding instantly and suturelessly, and close wounds (2 cm long × 0.5 cm deep) created on the back of Sprague–Dawley rats, which is impossible when using existing gold standard, fibrin glue, due to its weak wet tissue adhesion strength. Equally important, the new bioadhesives facilitate wound healing, and are completely degraded and absorbed without eliciting significant inflammatory response. Our results support that iCMBA technology is highly translational and could have broad impact on surgeries where surgical tissue adhesives, sealants, and hemostatic agents are used.
A facile approach is proposed for superior conformation and adhesion of wearable sensors to dry and wet skin. Bioinspired skin‐adhesive films are composed of elastomeric microfibers decorated with ...conformal and mushroom‐shaped vinylsiloxane tips. Strong skin adhesion is achieved by crosslinking the viscous vinylsiloxane tips directly on the skin surface. Furthermore, composite microfibrillar adhesive films possess a high adhesion strength of 18 kPa due to the excellent shape adaptation of the vinylsiloxane tips to the multiscale roughness of the skin. As a utility of the skin‐adhesive films in wearable‐device applications, they are integrated with wearable strain sensors for respiratory and heart‐rate monitoring. The signal‐to‐noise ratio of the strain sensor is significantly improved to 59.7 because of the considerable signal amplification of microfibrillar skin‐adhesive films.
Strong adhesion of wearable sensors to dry and wet skin is proposed by a novel approach. Micropatterned adhesive films are composed of microfibers decorated with mushroom‐shaped vinylsiloxane tips. Crosslinking the viscous tips directly on the skin significantly enhances the adhesion performance due to their great shape adaptation, which in turn highly increases the output signal quality of wearable strain sensors.
Few studies aiming to develop a glue with an underwater reusable adhesive property have been reported because combining the two properties of reusable adhesion and underwater adhesion into a single ...glue formulation is a challenging issue. Herein, preparation of a simple mixture of poly(vinyl alcohol) (PVA) and a well-known phenolic compound, namely, tannic acid (TA), results in an underwater glue exhibiting reusable adhesion. We named the adhesive VATA (PVA + TA). Using VATA, two stainless steel objects (0.77 kg each) are able to be instantly attached. In addition to the high adhesive strength, surface-applied VATA in water retains its adhesive capability even after 24 h. In contrast, cyanoacrylate applied under the same water condition rapidly loses its adhesive power. Another advantage is that VATA’s adhesion is reusable. Bonded objects can be forcibly detached, and then the detached ones can be reattached by the residual VATA. VATA maintains nearly 100% of its initial adhesive force, even after 10 repetitions of attach–detach cycles. VATA bonds various materials ranging from metals and polymers to ceramics. Particularly, we first attempt to test the toxicity of the underwater adhesives using an invertebrate nematode, Caenorhabditis elegans and gold fish (vertebrate) due to potential release to the environment.
Adhesion to wet and dynamic surfaces, including biological tissues, is important in many fields but has proven to be extremely challenging. Existing adhesives are cytotoxic, adhere weakly to tissues, ...or cannot be used in wet environments. We report a bioinspired design for adhesives consisting of two layers: an adhesive surface and a dissipative matrix. The former adheres to the substrate by electrostatic interactions, covalent bonds, and physical interpenetration. The latter amplifies energy dissipation through hysteresis. The two layers synergistically lead to higher adhesion energies on wet surfaces as compared with those of existing adhesives. Adhesion occurs within minutes, independent of blood exposure and compatible with in vivo dynamic movements. This family of adhesives may be useful in many areas of application, including tissue adhesives, wound dressings, and tissue repair.
A thermoplastic adhesive modified with iron oxide particles (IO) and graphene nanoplatelets (GNPs) has been used to ease the dismounting process of plastic component assemblies by using microwave or ...induction heating systems. GNPs have been added to an adhesive already modified with iron oxide particles (10% in weight) to melt the adhesive and separate adhesive joints in a more rapid and efficient way compared to the adhesive preliminarily adopted by the same authors. The IO-based thermoplastic adhesive was modified with three different GNP weight concentrations, namely 0.1%, 0.5%, and 1.0%. The mechanical properties have been evaluated through single lap joint (SLJ) tests. These tests showed that the maximum sustained load and the elastic moduli of the joints increase together with the increase of GNP percentages. Microwave or induction heating tests conducted on all the adhesive compositions showed that it is possible to melt the adhesive rapidly and thus separate the plastic joints in a very rapid way, 14 s, and 10 s respectively for the cases that embed 1% of GNPs. Scanning electron microscope (SEM) showed that the extruder can mix uniformly these particles without the formation of agglomerates.
Abstract Current medical adhesives based on cyanoacrylates typically exhibit cellular toxicity. In contrast, fibrin adhesives are non-toxic but have poor adhesive properties. To overcome these ...drawbacks we designed a simple and scalable adhesive precursor inspired by marine mussel adhesion that functioned with strong adhesion in wet conditions and with low cytotoxicity. Dopamine, an-amine derivative of an amino acid abundantly present in mussel adhesive proteins, was co-polymerised with a tri-functional vinyl monomer, to form a hyperbranched poly(β-amino ester) polymer termed poly(dopamine-co-acrylate) (PDA). A variety of molecular weights and crosslinking methods were analysed using an ex vivo porcine skin model and an almost 4 fold increase in wet adhesion strength was observed compared to TISSEEL® fibrin sealant. With a fast curing time, degradable properties and low cytotoxicity, PDA is highly attractive for medical purposes and could have a broad impact on surgeries where surgical tissue adhesives, sealants, and haemostatic agents are used.
Contemporary self-etch and multi-mode adhesives were introduced to ensure a fast and reliable bonding procedure. Yet, in terms of bond strength and stability they failed to perform as well as ...two-bottle, etch-and-rinse adhesives, which remain the gold standard in terms of durability. The purpose of this study was to assess the shear bond strength (SBS) of dental adhesives to dentin with different application protocols. Two self-etch (Adper Easy One and Xeno V) and two multi-mode adhesives (Single Bond Universal and Prime&Bond One Select) were used in the study. The highest SBS was obtained for Single Bond Universal applied in three layers, while the lowest, for Xeno V applied in one layer. Other tested adhesives obtained the highest SBS when applied in three layers. For all tested adhesives, multi-layer application resulted in an increase in adhesive layer thickness, as observed in SEM. The increased thickness of the adhesive layer produced by triple application of unfilled adhesives corresponded with higher SBS values. The present study showed that using triple adhesive layers with simplified adhesive systems can be recommended to improve their performance. Due to differences in the composition of self-etch and universal adhesives, the exact application protocol is product dependent.
Healable, adhesive, wearable, and soft human‐motion sensors for ultrasensitive human–machine interaction and healthcare monitoring are successfully assembled from conductive and human‐friendly hybrid ...hydrogels with reliable self‐healing capability and robust self‐adhesiveness. The conductive, healable, and self‐adhesive hybrid network hydrogels are prepared from the delicate conformal coating of conductive functionalized single‐wall carbon nanotube (FSWCNT) networks by dynamic supramolecular cross‐linking among FSWCNT, biocompatible polyvinyl alcohol, and polydopamine. They exhibit fast self‐healing ability (within 2 s), high self‐healing efficiency (99%), and robust adhesiveness, and can be assembled as healable, adhesive, and soft human‐motion sensors with tunable conducting channels of pores for ions and framework for electrons for real time and accurate detection of both large‐scale and tiny human activities (including bending and relaxing of fingers, walking, chewing, and pulse). Furthermore, the soft human‐motion sensors can be enabled to wirelessly monitor the human activities by coupling to a wireless transmitter. Additionally, the in vitro cytotoxicity results suggest that the hydrogels show no cytotoxicity and can facilitate cell attachment and proliferation. Thus, the healable, adhesive, wearable, and soft human‐motion sensors have promising potential in various wearable, wireless, and soft electronics for human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.
Flexible, wearable, healable, and adhesive soft strain sensors are successfully developed from a conductive and biocompatible hybrid hydrogel framework for ultrasensitive human–machine interaction and healthcare monitoring. They exhibit fast self‐healing ability (within 2 s), highly self‐healing efficiency (99%), robust self‐adhesiveness, and a tunable conducting framework for real‐time, wireless, and accurate detection in human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.
Recently, the realization of minimally invasive medical interventions on targeted tissues using wireless small‐scale medical robots has received an increasing attention. For effective implementation, ...such robots should have a strong adhesion capability to biological tissues and at the same time easy controlled detachment should be possible, which has been challenging. To address such issue, a small‐scale soft robot with octopus‐inspired hydrogel adhesive (OHA) is proposed. Hydrogels of different Young's moduli are adapted to achieve a biocompatible adhesive with strong wet adhesion by preventing the collapse of the octopus‐inspired patterns during preloading. Introduction of poly(N‐isopropylacrylamide) hydrogel for dome‐like protuberance structure inside the sucker wall of polyethylene glycol diacrylate hydrogel provides a strong tissue attachment in underwater and at the same time enables easy detachment by temperature changes due to its temperature‐dependent volume change property. It is finally demonstrated that the small‐scale soft OHA robot can efficiently implement biomedical functions owing to strong adhesion and controllable detachment on biological tissues while operating inside the body. Such robots with repeatable tissue attachment and detachment possibility pave the way for future wireless soft miniature robots with minimally invasive medical interventions.
A biocompatible small‐scale adhesive robot is developed by using hydrogels of different Young's moduli with octopus‐inspired micropatterns. The robot can continuously and efficiently conduct biomedical functions in underwater environment due to controllable wet tissue adhesion.
Robust adhesion to wet, salt-encrusted, corroded and slimy surfaces has been an essential adaptation in the life histories of sessile marine organisms for hundreds of millions of years, but it ...remains a major impasse for technology. Mussel adhesion has served as one of many model systems providing a fundamental understanding of what is required for attachment to wet surfaces. Most polymer engineers have focused on the use of 3,4-dihydroxyphenyl-l-alanine (Dopa), a peculiar but abundant catecholic amino acid in mussel adhesive proteins. The premise of this Review is that although Dopa does have the potential for diverse cohesive and adhesive interactions, these will be difficult to achieve in synthetic homologs without a deeper knowledge of mussel biology; that is, how, at different length and time scales, mussels regulate the reactivity of their adhesive proteins. To deposit adhesive proteins onto target surfaces, the mussel foot creates an insulated reaction chamber with extreme reaction conditions such as low pH, low ionic strength and high reducing poise. These conditions enable adhesive proteins to undergo controlled fluid-fluid phase separation, surface adsorption and spreading, microstructure formation and, finally, solidification.
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