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

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

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

Modular approaches to multivalent and bioactive materials using supramolecular polymers.

A new and highly attractive supramol. system has been developed which is based on low mol. wt. biocompatible prepolymers end-functionalized with quadruple hydrogen bonding ureido-pyrimidinone (UPy) moieties. The non-covalent interactions between the UPy units link the prepolymers together. Because of the reversible nature of the hydrogen bonding this system can be perfectly used in a modular approach. We propose that UPy functionalized polymers and biomols. can assemble into bioactive materials that can be made multivalent by simply mixing in different epitopes. Several UPy mols. have been synthesized varying from fluorescent dyes to peptides and proteins. The recognition of avidin with UPy-biotin contg. supramol. polymer surfaces and the interactions between cells and UPy surfaces modified with cell adhesion peptides have been studied. In this way we propose to get exquisite control over processes such as adhesion, growth, proliferation and differentiation of cells, which are prerequisites for applications like tissue engineering

Supramolecular biomaterials : a modular approach towards tissue engineering

Supramolecular chemistry is an exciting area of science that plays a central role in bringing different disciplines together, ranging from molecular medicine to nanotechnology. Materials science based on supramolecular interactions is an emerging field, which has made important steps forward in the past ten years. The self-assembly of small synthetic molecules into long-chain architectures gives rise to the careful design of supramolecular polymers or fibers based on highly directional, reversible, non-covalent interactions. Much afford is put into the development of supramolecular (polymeric) materials with true materials properties, both in solution and in the solid state. These supramolecular materials are beginning to reach the market in all kind of applications. The field of regenerative medicine in general and that of tissue engineering in particular is one of the most challenging areas in which supramolecular materials might have a high potential. In tissue engineering, the biological environment and the interactions of cells with the artificial biomaterial is of utmost importance for the functioning of the implant, i.e. the engineered tissue. Ideal biomaterials do not only have to fulfil the biomaterials trinity of tuneable mechanical properties, regulation of the degradability and the ease for bioactivity incorporation, but also have to mimic the natural environment where the materials are brought into. Therefore, a modular, self-assembly approach using several supramolecular building blocks is an exquisite way to produce such "responsive" biomaterials. It is proposed that the artificial materials described in this account have the same type of dynamic ability to adapt its biofunctionality as is so well known for the living cells in the host tissue. This account will highlight two systems, i.e. self-assembling oligopeptide fibers as pioneered by Stupp et al. and Zhang et al., and our hydrogen-bonded supramolecular polymers, to show the potential of a modular approach to dynamic biomaterials for tissue engineering

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