75 research outputs found
Introduction of anti-fouling coatings at the surface of supramolecular elastomeric materials:via post-modification of reactive supramolecular additives
Protein repellent coatings have been extensively studied to introduce anti-fouling properties at material surfaces. Here we introduce a covalent anti-fouling coating at the surface of supramolecular ureidopyrimidinone (UPy) based materials introduced via post-modification of reactive UPy-functionalized tetrazine additives incorporated into the supramolecular polymer material. After material formulation, an anti-fouling coating comprised of bicyclononyne (BCN) functionalized poly(ethylene glycol) (PEG) polymers was reacted. This coating was covalently attached to the surface via a highly selective electron-demand Diels-Alder cycloaddition between tetrazine and BCN. The anti-fouling properties of three different BCN-PEG polymers, mono-functional-PEG-BCN, bi-functional-PEG-BCN and star-PEG-BCN, respectively, were systematically studied. The mono-functional-PEG-BCN showed minor reduction in both protein adsorption and cell adhesion, whereas the bi-functional-PEG-BCN and the star-PEG-BCN polymer coating demonstrated complete anti-fouling performance, both towards protein adhesion as well as cell adhesion. Additionally, a bioorthogonal ligation strategy was performed in culture medium in the presence of cells showing a similar behavior for the three anti-fouling coatings, which indicates that this strategy can be applied for post-modification reactions in a complex environment.</p
Full-field hygroscopic characterization of tough 3D-printed supramolecular hydrogels
Chain-extended ureido-pyrimidinone poly(ethylene glycol) (CE-UPy-PEG) is a supramolecular hydrogel with excellent mechanical properties and shape memory capabilities, making it highly suitable for 3D printing of complex biomimetic structures to mimic biomaterials. However, its transient hygroexpansion response under environmental change, specifically relative humidity (RH), which is strongly affected by the supramolecular sub-structure, is poorly understood. Therefore, a high-precision full-field fiber-swelling methodology is applied to 3D-printed CE-UPy-PEG fibers, enabling investigation of the influence of PEG chain length (1.5, 3, and 10 kg/mol studied here) and RH rate from wet to dry on the longitudinal and transverse surface strain evolution during multiple RH cycles. The PEG length directly influences the fibers' hygroscopic properties, because only CE-UPy-PEG3k and CE-UPy-PEG10k exhibit a phase transformation from semicrystalline to amorphous at higher RH levels, which is fully described by a phenomenological phase transformation model. Furthermore, all fibers display cyclic repeatability (shape memory), increased swelling for longer PEG chains and lower RH rate, and disappearance of sub-millimeter-sized tube-like voids after wetting.</p
Mesoscale characterization of supramolecular transient networks using SAXS and Rheology
Abstract: Hydrogels and, in particular, supramolecular hydrogels show promising properties for application in regenerative medicine because of their ability to adapt to the natural environment these materials are brought into. However, only few studies focus on the structure-property relationships in supramolecular hydrogels. Here, we study in detail both the structure and the mechanical properties of such a network, composed of poly(ethylene glycol), end-functionalized with ureido-pyrimidinone fourfold hydrogen bonding units. This network is responsive to triggers such as concentration, temperature and pH. To obtain more insight into the sol-gel transition of the system, both rheology and small-angle X-ray scattering (SAXS) are used. We show that the sol-gel transitions based on these three triggers, as measured by rheology, coincide with the appearance of a structural feature in SAXS. We attribute this feature to the presence of hydrophobic domains where cross-links are formed. These results provide more insight into the mechanism of network formation in these materials, which can be exploited for tailoring their behavior for biomedical applications, where one of the triggers discussed might be used
Оцінювання зволоженості гірських водозборів при математичному моделюванні дощових паводків
Розроблено процедуру оцінювання зволоженості водозбору, яка не потребує тривалого моделювання в оперативних умовах.Разработана процедура оценивания увлажненности водосбора, которая исключает необходимость продолжительного моделирования в оперативных условиях
Supramolecular polymers form tactoids through liquid-liquid phase separation
Liquid-liquid phase separation (LLPS) of biopolymers has recently been shown to play a central role in the formation of membraneless organelles with a multitude of biological functions1-3. The interplay between LLPS and macromolecular condensation is part of continuing studies4,5. Synthetic supramolecular polymers are the non-covalent equivalent of macromolecules but they are not reported to undergo LLPS yet. Here we show that continuously growing fibrils, obtained from supramolecular polymerizations of synthetic components, are responsible for phase separation into highly anisotropic aqueous liquid droplets (tactoids) by means of an entropy-driven pathway. The crowding environment, regulated by dextran concentration, affects not only the kinetics of supramolecular polymerizations but also the properties of LLPS, including phase-separation kinetics, morphology, internal order, fluidity and mechanical properties of the final tactoids. In addition, substrate-liquid and liquid-liquid interfaces proved capable of accelerating LLPS of supramolecular polymers, allowing the generation of a myriad of three-dimensional-ordered structures, including highly ordered arrays of micrometre-long tactoids at surfaces. The generality and many possibilities of supramolecular polymerizations to control emerging morphologies are demonstrated with several supramolecular polymers, opening up a new field of matter ranging from highly structured aqueous solutions by means of stabilized LLPS to nanoscopic soft matter.Drug Delivery Technolog
A Fast pH-Switchable and Self-Healing Supramolecular Hydrogel Carrier for Guided, Local Catheter Injection in the Infarcted Myocardium
Supramolecular & Biomaterials Chemistr
Oxidative stress in pancreatic alpha and beta cells as a selection criterion for biocompatible biomaterials
The clinical success rate of islet transplantation, namely independence from insulin injections, is limited by factors that lead to graft failure, including inflammation, acute ischemia, acute phase response, and insufficient vascularization. The ischemia and insufficient vascularization both lead to high levels of oxidative stress, which are further aggravated by islet encapsulation, inflammation, and undesirable cell-biomaterial interactions. To identify biomaterials that would not further increase damaging oxidative stress levels and that are also suitable for manufacturing a beta cell encapsulation device, we studied five clinically approved polymers for their effect on oxidative stress and islet (alpha and beta cell) function. We found that 300 poly(ethylene oxide terephthalate) 55/poly(butylene terephthalate) 45 (PEOT/PBT300) was more resistant to breakage and more elastic than other biomaterials, which is important for its immunoprotective function. In addition, it did not induce oxidative stress or reduce viability in the MIN6 beta cell line, and even promoted protective endogenous antioxidant expression over 7 days. Importantly, PEOT/PBT300 is one of the biomaterials we studied that did not interfere with insulin secretion in human islets.Diabetes mellitus: pathophysiological changes and therap
Cardiac patching and the regeneration of infarcted myocardium: Where do we go from here?
EVALUATION OF: Serpooshan V, Zhao M, Metzler SA et al. The effect of bioengineered acellular collagen patch on cardiac remodeling and ventricular function postmyocardial infarction. Biomaterials 34, 9048-9055 (2013). The decline of cardiac function in the post-myocardial infarcted (MI) heart is due to two essential problems: massive loss of contractile cardiomyocytes, and loss of structural and mechanical tissue integrity due to ongoing remodeling of scar tissue, often leading to left ventricular dilation. Serpooshan et al. demonstrate that an engineered acellular type I collagen patch with optimized mechanical properties, grafted onto the epicardium of infarcted adult murine hearts following ligation of the left anterior descending artery, significantly improves cardiac function and reduces left ventricular remodeling 4 weeks postinjury. While these short-term results are encouraging and, like in other studies, prove the relevance of mechanically supporting the injured myocardium, optimization of the approach in terms of time and manner of intervention, as well as origin of the biomaterial, is needed to warrant future clinical application. © 2014 Future Medicine Ltd
Introduction of nature's complexity in engineered blood-compatible biomaterials
Biomaterials with excellent blood-compatibility are needed for applications in vascular replacement therapies, such as vascular grafts, heart valves and stents, and in extracorporeal devices such as hemodialysis machines and blood-storage bags. The modification of materials that are being used for blood-contacting devices has advanced from passive surface modifications to the design of more complex, smart biomaterials that respond to relevant stimuli from blood to counteract coagulation. Logically, the main source of inspiration for the design of new biomaterials has been the endogenous endothelium. Endothelial regulation of hemostasis is complex and involves a delicate interplay of structural components and feedback mechanisms. Thus, challenges to develop new strategies for blood-compatible biomaterials now lie in incorporating true feedback controlled mechanisms that can regulate blood compatibility in a dynamic way. Here, supramolecular material systems are highlighted as they provide a promising platform to introduce dynamic reciprocity, due to their inherent dynamic nature
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