consist of soft collagen with a water con tent of around 60-80%, their unique structural characteristics provide high tensile strength and excellent fatigue resis tance. [1][2][3][4] The high strength of tendons is derived from the hierarchical structure and anisotropy of collagen fibers formed by crosslinking collagen molecules and gathered to form larger bundles. Tendon tobone integration, called enthesis, is another important feature of tendons. The enthesis is the part where the tendon and ligament insert into the bone and transmit the mechanical load from muscle to bone. The enthesis is composed of four zones (pure dense fibrous connective tissue, uncalcified fibrocartilage, calcified fibro cartilage, and bone) exhibiting gradients in tissue organization with varying cellular composition (collagentomineral), which leads to high adhesive, mechanical prop erties between the tendon and bone. [5][6][7][8] The strong mechanical properties of anisotropic, hierarchically aligned collagen fibers in tendons and the unique tendonto bone integration enable an effective transfer of high mechan ical stress. In general, this unique and complex interface and the corresponding mechanical properties of tendon and liga ment are difficult to mimic using biomaterials.Recently, there have been significant advances in hydrogels exhibiting high mechanical properties or adhesive characteris tics which are extensively improved compared to that of con ventional hydrogels. However, most reported hydrogels either have high adhesion but significantly inferior mechanical properties than those of tendons [9][10][11][12][13][14][15][16][17][18][19] or have strong mechanical properties but very weak adhesion. [20][21][22][23][24][25][26][27][28][29][30][31][32][33] Very recent studies have attempted to simultaneously achieve high adhesiveness and excellent mechanical properties of hydrogels for bioad hesion; [34][35][36] nevertheless those hydrogels are far softer than the tendon. Also, most of them have focused on the adhe sion to relatively soft tissues such as heart, skin, cartilage, and tendon; [9][10][11][12][13][14][15][16][17][18][19]35,36] there have been no reports on mechanically enhanced hydrogel with strong adhesion to the bone. This is due to the tradeoff between the high modulus or strength of hydrogel and its adhesiveness; it is hard to achieve high adhe sion of stiff and strong hydrogels to a solid surface.Hence, this study proposes an anisotropic, stiff, and strong hydrogel with a high adhesiveness to the bone, mimicking both the mechanical properties of the tendon and the tendon tobone interface. A tough triple network (TN) hydrogel Tendon consists of soft collagen, yet it is mechanically strong and firmly adhered to the bone owing to its hierarchically anisotropic structure and unique tendon-to-bone integration (enthesis), respectively. Despite the recent advances in biomaterials, hydrogels simultaneously providing tendon-like high mechanical properties and strong adhesion to bone-mimicking enthesis is still challenging....
The increased use of medical devices combined with the emergence of new multi‐drug‐resistant bacteria has enhanced research on biomaterial‐related infections. Small size of Ag nanoparticles (AgNPs) has already been suggested to show high antibacterial activities. However, small AgNPs tend to aggregate during preparation, resulting in a significant decrease in their antibacterial properties. Three‐dimensional (3D) graphene can be used as a support matrix, for the fixation of precious metal NPs and the maximization of the load. Here, we present a synthetic poly(amino acid), specifically, polyaspartamide modified by ethylenediamine and ethanolamine [PolyAspAm(EDA/EA)], which was mixed with tannic acid and graphene oxide to fabricate an ultralight 3D graphene hybrid aerogel. Transmission electron microscopy (TEM) revealed AgNP loading on the aerogel with the size of less than 50 nm uniformly dispersed, and AgNP loading on the aerogels led to the inhibition of antibacterial cell growth. The measured antibacterial activity, as determined by the inhibition zone and optical density in test, demonstrated that PolyAspAm(EA/EDA)/TA‐GO‐AgNP has a bacteriostatic and bactericidal effect against Staphylococcus aureus and Escherichia coli, thereby suggesting that this 3D polymer graphene composite gel has potential as a novel antibacterial material for a wide range of clinical applications.
A facile fabrication of strongly adhesive hydrogel based on high‐molecular‐weight poly(2‐ethyl‐2‐oxazoline) (PEOX) and tannic acid (TA) has been demonstrated. PEOX and TA form instantaneous complex gel via strong hydrogen bonding interaction by simple mixing in an aqueous system. The characteristics of the PEOX–TA complex gels was investigated by using Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy to reveal their network structure, composition, and thermal properties. The prepared wet complex gel system demonstrated excellent adhesive performance on different substrates with comparable results to pure PEOX polymer. It was considered that many factors affect the adhesive performance of the PEOX–TA gel such as the TA content, the molecular weight of PEOX, and water content. This adhesive gel system has potential for use in various fields including biomedical application as a novel and low‐cost adhesive or sealant. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48285.
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