Cell‐free approaches to in situ tissue engineering require materials that are mechanically stable and are able to control cell‐adhesive behavior upon implantation. Here, the development of mechanically stable grafts with non‐cell adhesive properties via a mix‐and‐match approach using ureido‐pyrimidinone (UPy)‐modified supramolecular polymers is reported. Cell adhesion is prevented in vitro through mixing of end‐functionalized or chain‐extended UPy‐polycaprolactone (UPy‐PCL or CE‐UPy‐PCL, respectively) with end‐functionalized UPy‐poly(ethylene glycol) (UPy‐PEG) at a ratio of 90:10. Further characterization reveals intimate mixing behavior of UPy‐PCL with UPy‐PEG, but poor mechanical properties, whereas CE‐UPy‐PCL scaffolds are mechanically stable. As a proof‐of‐concept for the use of non‐cell adhesive supramolecular materials in vivo, electrospun vascular scaffolds are applied in an aortic interposition rat model, showing reduced cell infiltration in the presence of only 10% of UPy‐PEG. Together, these results provide the first steps toward advanced supramolecular biomaterials for in situ vascular tissue engineering with control over selective cell capturing.
Peptides and polymers are the “elite” building blocks in hydrogel fabrication where the typical approach consists of coupling specific peptide sequences (cell adhesive and/or enzymatically cleavable) to polymer chains aiming to obtain controlled cell responses (adhesion, migration, differentiation). However, the use of polymers and peptides as structural components for fabricating supramolecular hydrogels is less well established. Here, the literature on the design of peptide/polymer systems for self‐assembly into hybrid hydrogels, as either peptide‐polymer conjugates or combining both components individually, is reviewed. The properties (stiffness, mesh structure, responsiveness, and biocompatibility) of the hydrogels are then discussed from the viewpoint of their potential biomedical applications. 相似文献
siRNA delivery remains a major challenge in RNAi‐based therapy. Here, we report for the first time that an amphiphilic dendrimer is able to self‐assemble into adaptive supramolecular assemblies upon interaction with siRNA, and effectively delivers siRNAs to various cell lines, including human primary and stem cells, thereby outperforming the currently available nonviral vectors. In addition, this amphiphilic dendrimer is able to harness the advantageous features of both polymer and lipid vectors and hence promotes effective siRNA delivery. Our study demonstrates for the first time that dendrimer‐based adaptive supramolecular assemblies represent novel and versatile means for functional siRNA delivery, heralding a new age of dendrimer‐based self‐assembled drug delivery in biomedical applications. 相似文献
Reported here are laminated membrane electrodes, an improved design and more advantageous method of fabrication for previously reported thin layer cell electrode systems developed on track‐etch membranes. The laminated membrane approach potentially further improves flow resistance by dramatically reducing the surface area to volume ratio, but also produces a cohesive device that can be more readily applied to a broad range of applications. In addition, this new fabrication method was implemented in a scalable, commercial process and resulting product demonstrations indicate that volume manufacturing is feasible. Characterization of laminated membrane electrodes reveal redox cycling amplification factors as high as 30 with linear responses to variable concentrations of redox couple. These performance characteristics are shown to be comparable to similar generator‐collector systems fabricated through much more laborious laboratory methods. This combination of added versatility, cost‐reduced fabrication and exceptional performance clearly reveals unrealized potential of track‐etch membrane approaches and boosts their candidacy as powerful new options for generator‐collector electrode systems. 相似文献
To be used successfully in continuous reactor systems, enzymes must either be retained using filtration membranes or immobilized on a solid component of the reactor. Whereas the first approach requires large amounts of energy, the second approach is limited by the low temporal stability of enzymes under operational conditions. To circumvent these major stumbling blocks, we have developed a strategy that enables the reversible supramolecular immobilization of bioactive enzyme–polymer conjugates at the surface of filtration membranes. The polymer is produced through a reversible addition–fragmentation transfer method; it contains multiple adamantyl moieties that are used to bind the resulting conjugate at the surface of the membrane which has surface‐immobilized cyclodextrin macrocycles. This supramolecular modification is stable under operational conditions and allows for efficient biocatalysis, and can be reversed by competitive host–guest interactions. 相似文献
Wound dressings are vital for cutaneous wound healing. In this study, a bi‐layer dressing composed of polyvinyl alcohol/carboxymethyl cellulose/polyethylene glycol (PVA/CMC/PEG) hydrogels is produced through a thawing–freezing method based on the study of the pore size of single‐layer hydrogels. Then the physical properties and healing of full‐thickness skin defects treated with hydrogels are inspected. The results show that the pore size of the single‐layer PVA/CMC/PEG hyrogel can be controlled. The obtained non‐adhesive bi‐layer hydrogels show gradually increasing pore sizes from the upper to the lower layer and two layers are well bonded. In addition, bi‐layer dressings with good mechanical properties can effectively prevent bacterial penetration and control the moisture loss of wounds to maintain a humid environment for wounds. A full‐thickness skin defect test shows that bi‐layer hydrogels can significantly accelerate wound closure. The experiment indicates that the bi‐layer PVA/CMC/PEG hydrogels can be used as potential wound dressings. 相似文献
Fluorescent polymeric nanoparticles (FPNs) with aggregation‐induced emission (AIE) property have received increasing attention and possess promising biomedical application potential in the recent years. Many efforts have been devoted to the fabrication methodologies of FPNs and significant advance has been achieved. In this contribution, a novel strategy for the fabrication of AIE‐active amphiphilic copolymers is reported for the first time based on the Ce(IV) redox polymerization. As an example, ene group containing AIE‐active dye (named as Phe‐alc) is directly grafted onto a water soluble polymer polyethylene glycol (PEG) in H2O/THF system under low temperature. Thus‐obtained amphiphilic fluorescent polymers will self‐assemble into FPNs with ultra‐low critical micelle concentration, ultra‐brightness, and great water dispersibility. Biological evaluation results suggest that the PEG‐poly(Phe‐alc) possess excellent biocompatibility and can be used for tracing their behavior in cells using confocal laser scanning microscope. These features make PEG‐poly(Phe‐alc) FPNs promising candidates for many biomedical applications, such as cell imaging, drug delivery vehicles, and targeted tracing. More importantly, many other functional groups can also be incorporated into these AIE‐active FPNs through the redox polymerization. Therefore, the redox polymerization should be a facile and effective strategy for fabrication of AIE‐active FPNs.
Dual electrospinning can be used to make multifunctional scaffolds for regenerative medicine applications. Here, two supramolecular polymers with different material properties are electrospun simultaneously to create a multifibrous mesh. Bisurea (BU)‐based polycaprolactone, an elastomer providing strength to the mesh, and ureido‐pyrimidinone (UPy) modified poly(ethylene glycol) (PEG), a hydrogelator, introducing the capacity to deliver compounds upon swelling. The dual spun scaffolds are modularly tuned by mixing UPyPEG hydrogelators with different polymer lengths, to control swelling of the hydrogel fiber, while maintaining the mechanical properties of the scaffold. Stromal cell derived factor 1 alpha (SDF1α) peptides are embedded in the UPyPEG fibers. The swelling and erosion of UPyPEG increase void spaces and released the SDF1α peptide. The functionalized scaffolds demonstrate preferential lymphocyte recruitment proposed to be created by a gradient formed by the released SDF1α peptide. This delivery approach offers the potential to develop multifibrous scaffolds with various functions. 相似文献
A unique example of supramolecular polymerisation in water based on monomers with nanomolar affinities, which yield rod‐like materials with extraordinarily high thermodynamic stability, yet of finite length, is reported. A small library of charge‐neutral dendritic peptide amphiphiles was prepared, with a branched nonaphenylalanine‐based core that was conjugated to hydrophilic dendrons of variable steric demand. Below a critical size of the dendron, the monomers assemble into nanorod‐like polymers, whereas for larger dendritic side chains frustrated growth into near isotropic particles is observed. The supramolecular morphologies observed by electron microscopy, X‐ray scattering and diffusion NMR spectroscopy studies are in agreement with the mechanistic insights obtained from fitting polymerisation profiles: non‐cooperative isodesmic growth leads to degrees of polymerisation that match the experimentally determined nanorod contour lengths of close to 70 nm. The reported designs for aqueous self‐assembly into well‐defined anisotropic particles has promising potential for biomedical applications and the development of functional supramolecular biomaterials, with emerging evidence that anisotropic shapes in carrier design outperform conventional isotropic materials for targeted imaging and therapy. 相似文献
Conventional photosensing devices work mainly by electron processing and transport, while visual systems in intelligence work by integrative ion/electron signals. To realize smarter photodetectors, some photoionic device or the combination of ionic and electronic devices are necessary. Now, an ion‐transport‐based self‐powered photodetector is presented based on an asymmetric carbon nitride nanotube membrane, which can realize fast, selective, and stable light detection while being self‐powered. Local charges are continuously generated at the irradiated side of the membrane, and none (fewer) at the non‐irradiated side. The resulting surface charge gradient in carbon nitride nanotube will drive ion transport in the cavity, thus realizing the function of ionic photodetector. With advantages of low cost and easy fabrication process, the concept of ionic photodetectors based on carbon nitride anticipates wide applications for semiconductor biointerfaces. 相似文献
Stretchable self‐healing urethane‐based biomaterials have always been crucial for biomedical applications; however, the strength is the main constraint of utilization of these healable materials. Here, a series of novel, healable, elastomeric, supramolecular polyester urethane nanocomposites of poly(1,8‐octanediol citrate) and hexamethylene diisocyanate reinforced with cellulose nanocrystals (CNCs) are introduced. Nanocomposites with various amounts of CNCs from 10 to 50 wt% are prepared using solvent casting technique followed by the evaluation of their microstructural features, mechanical properties, healability, and biocompatibility. The synthesized nanocomposites indicate significantly higher tensile modulus (approximately 36–500‐fold) in comparison to the supramolecular polymer alone. Upon exposure to heat, the materials can reheal, but nevertheless when the amount of CNC is greater than 10 wt%, the self‐healing ability of nanocomposites is deteriorated. These materials are capable of rebonding ruptured parts and fully restoring their mechanical properties. In vitro cytotoxicity test of the nanocomposites using human dermal fibroblasts confirms their good cytocompatibility. The optimized structure, self‐healing attributes, and noncytotoxicity make these nanocomposites highly promising for tissue engineering and other biomedical applications. 相似文献
Induction of a functional, tight monolayer of renal epithelial cells on a synthetic membrane to be applied in a bioartificial kidney device requires for bio‐activation of the membrane. The current golden standard in bio‐activation is the combination of a random polymeric catechol (L‐DOPA) coating and collagen type IV (Col IV). Here the possibility of replacing this with defined monomeric catechol functionalization on a biomaterial surface using supramolecular ureido‐pyrimidinone (UPy)‐moieties is investigated. Monomeric catechols modified with a UPy‐unit are successfully incorporated and presented in supramolecular UPy‐polymer films and membranes. Unfortunately, these UPy‐catechols are unable to improve epithelial cell monolayer formation over time, solely or in combination with Col IV. L‐DOPA combined with Col IV is able to induce a tight monolayer capable of transport on electrospun supramolecular UPy‐membranes. This study shows that a random polymeric catechol coating cannot be simply mimicked by defined monomeric catechols as supramolecular additives. There is still a long way to go in order to synthetically mimic simple natural structures. 相似文献
Miniaturized solid‐state ion sensors based on field‐effect transistors on silicon can take advantage of the capabilities of microelectronics and microsystems technology for the integration of combined functionalities. Optimized solid‐state chemical sensors usually require specific materials and fabrication processes. However, if standard fabrication processes can be used, integrated chemical sensor systems can be developed in a shorter time and in a cost effective way. We show that, for applications in which a long operating time is not required, such as in disposable biomedical sensors, good integrated sensor systems can be fabricated with standard materials and processes. Specific examples are presented, such as multisensor systems, sensors with integrated signal‐processing circuits and sensors with particle manipulation electrodes. 相似文献