Tough dual nanocomposite hydrogels with inorganic hybrid crosslinking
TL;DR: A dual nanocomposite hydrogel with inorganic hybrid crosslinking was fabricated through a simultaneous sol-gel technique and free radical polymerization and exhibited excellent fatigue resistant properties.
Abstract: A dual nanocomposite hydrogel with inorganic hybrid crosslinking was fabricated through a simultaneous sol–gel technique and free radical polymerization. Due to the multi-strengthening mechanism of the dual nanocomposite, the hydrogel was super tough and strong with a compressive stress of 32.00 MPa without rupture even at 100% strain, while it exhibited excellent fatigue resistant properties.
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TL;DR: In this paper, a review aimed at synergistically reporting: (i) general design principles for hydrogels to achieve extreme mechanical and physical properties, (ii) implementation strategies for the design principles using unconventional polymer networks, and (iii) future directions for the orthogonal design of hydrogel to achieve multiple combined mechanical, physical, chemical, and biological properties.
Abstract: Hydrogels are polymer networks infiltrated with water. Many biological hydrogels in animal bodies such as muscles, heart valves, cartilages, and tendons possess extreme mechanical properties including being extremely tough, strong, resilient, adhesive, and fatigue-resistant. These mechanical properties are also critical for hydrogels' diverse applications ranging from drug delivery, tissue engineering, medical implants, wound dressings, and contact lenses to sensors, actuators, electronic devices, optical devices, batteries, water harvesters, and soft robots. Whereas numerous hydrogels have been developed over the last few decades, a set of general principles that can rationally guide the design of hydrogels using different materials and fabrication methods for various applications remain a central need in the field of soft materials. This review is aimed at synergistically reporting: (i) general design principles for hydrogels to achieve extreme mechanical and physical properties, (ii) implementation strategies for the design principles using unconventional polymer networks, and (iii) future directions for the orthogonal design of hydrogels to achieve multiple combined mechanical, physical, chemical, and biological properties. Because these design principles and implementation strategies are based on generic polymer networks, they are also applicable to other soft materials including elastomers and organogels. Overall, the review will not only provide comprehensive and systematic guidelines on the rational design of soft materials, but also provoke interdisciplinary discussions on a fundamental question: why does nature select soft materials with unconventional polymer networks to constitute the major parts of animal bodies?
312 citations
TL;DR: It is anticipated that hybridization of the hydrogen bonding monomer with a variety of bioactive inorganic nanoparticles will offer new possibilities to develop numerous bioinks for 3D-printing of desired bioscaffolds to realize individualized repair of degenerated load-bearing tissues.
Abstract: The emerging 3D bioprinting technique that is strongly dependent on the development of bioinks offers a promising opportunity to customize personalized bioscaffolds for precision and individualized therapy of bone defects Hydrogels are one sort of attractive scaffolding materials due to their resemblance to extracellular matrices Although much progress has been made in designing and fabricating high strength hydrogels, very few of them have been extended to the treatment of bone defects In this work, we developed a hybrid bioink composed of a hydrogen bonding monomer (N-acryloyl glycinamide) (NAGA) and nanoclay The hybrid ink could be conveniently tailored as a high strength PNAGA-Clay composite scaffold under UV light illumination of printed prehydrogel The hydrogen bonding combined with physical cross-linking of nanoclay contributed to the superior mechanical performances as well as swelling stability of the hydrogels and bioscaffols The sustainable release of intrinsic Mg2+ and Si4+ from the PNAG
172 citations
TL;DR: The addition of Laponite nanoclay can effectively improve the mechanical and biological properties of hydrogel composites.
Abstract: Three dimensional (3D) bioprinting technology enables the freeform fabrication of complex constructs from various hydrogels and is receiving increasing attention in tissue engineering. The objective of this study is to develop a novel self-supporting direct hydrogel printing approach to extrude complex 3D hydrogel composite structures in air without the help of a support bath. Laponite, a member of the smectite mineral family, is investigated to serve as an internal scaffold material for the direct printing of hydrogel composite structures in air. In the proposed printing approach, due to its yield-stress property, Laponite nanoclay can be easily extruded through a nozzle as a liquid and self-supported after extrusion as a solid. Its unique crystal structure with positive and negative charges enables it to be mixed with many chemically and physically cross-linked hydrogels, which makes it an ideal internal scaffold material for the fabrication of various hydrogel structures. By mixing Laponite nanoclay wi...
161 citations
TL;DR: The application of MXene materials in the fabrication of NC hydrogels with enhanced mechanical and drug release behaviors is revealed and can be attributed to the honeycomb-like fine structure with uniform pores as well as more flexible polymer chains inNC hydrogel networks.
Abstract: A highly stretchable nanocomposite (NC) hydrogel was fabricated via in situ free radical polymerization of acrylamide. In particular, an exfoliated two-dimensional MXene (Ti3C2) nanosheet was utilized as a crosslinker instead of traditional organic crosslinkers. The exfoliated Ti3C2 nanosheets were confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS) measurements. Compared with traditional organic crosslinked N,N-methylene bisacrylamide (BIS)/polyacrylamide (PAM) hydrogels (fracture strength of 32.0 kPa and elongation of 109.6%), the synthesized Ti3C2/PAM NC hydrogels exhibited greatly improved mechanical properties with fracture strengths of 66.5 to 102.7 kPa, compressive strengths of 400.6 to 819.4 kPa and elongations at break of 2158.6% to 3047.5% as the Ti3C2 content increases from 0.0145% to 0.0436%. The enhanced mechanical performances can be attributed to the honeycomb-like fine structure with uniform pores as well as more flexible polymer chains in NC hydrogel networks. When loaded with drugs, Ti3C2/PAM NC hydrogels exhibited good sustained-release performance, higher drug loading amounts (97.5-127.7 mg g-1) and higher percentage releases (62.1-81.4%), greatly superior to those of the BIS/PAM hydrogel (46.4 mg g-1, 45.0%). Our work reveals the application of MXene materials in the fabrication of NC hydrogels with enhanced mechanical and drug release behaviors.
68 citations
TL;DR: Based on their high mechanical stability, these supertough composite hydrogels are demonstrated to exhibit on‐demand drug release, which is controlled by an external mechanical stimulation (both in vitro and in vivo).
Abstract: Despite their potential in various fields of bioapplications, such as drug/cell delivery, tissue engineering, and regenerative medicine, hydrogels have often suffered from their weak mechanical properties, which are attributed to their single network of polymers. Here, supertough composite hydrogels are proposed consisting of alginate/polyacrylamide double-network hydrogels embedded with mesoporous silica particles (SBA-15). The supertoughness is derived from efficient energy dissipation through the multiple bondings, such as ionic crosslinking of alginate, covalent crosslinking of polyacrylamide, and van der Waals interactions and hydrogen bondings between SBA-15 and the polymers. The superior mechanical properties of these hybrid hydrogels make it possible to maintain the hydrogel structure for a long period of time in a physiological solution. Based on their high mechanical stability, these hybrid hydrogels are demonstrated to exhibit on-demand drug release, which is controlled by an external mechanical stimulation (both in vitro and in vivo). Moreover, different types of drugs can be separately loaded into the hydrogel network and mesopores of SBA-15 and can be released with different speeds, suggesting that these hydrogels can also be used for multiple drug release.
60 citations
References
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4,511 citations
TL;DR: This work highlights recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for biomedical and biological applications and shows how such systems' intelligent behavior can be used in sensors, microarrays, and imaging.
Abstract: Hydrophilic polymers are the center of research emphasis in nanotechnology because of their perceived “intelligence”. They can be used as thin films, scaffolds, or nanoparticles in a wide range of biomedical and biological applications. Here we highlight recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for these applications. Natural, biohybrid, and synthetic hydrophilic polymers and hydrogels are analyzed and their thermodynamic responses are discussed. In addition, examples of the use of hydrogels for various therapeutic applications are given. We show how such systems’ intelligent behavior can be used in sensors, microarrays, and imaging. Finally, we outline challenges for the future in integrating hydrogels into biomedical applications.
3,524 citations
3,307 citations
TL;DR: Recent progress in overcoming challenges with regards to effectively delivering hydrogels inside the body without implantation, prolonging the release kinetics of drugs fromhydrogels, and expanding the nature of drugs which can be delivered using hydrogel-based approaches is discussed.
3,140 citations