Introduction of anti-fouling coatings at the surface of supramolecular elastomeric materials:via post-modification of reactive supramolecular additives

\u3cp\u3eProtein 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.\u3c/p\u3

Size-selective binding of sodium and potassium ions in nanoporous thin films of polymerized liquid crystals

\u3cp\u3eThe development of a nanoporous material from a columnar liquid crystalline complex between a polymerizable benzoic acid derivative and a 1,3,5-tris(1H-benzo[d]imidazol-2-yl)benzene template molecule is described. The morphology of the liquid crystalline complex is retained upon polymerization and quantitative removal of the template molecule affords a nanoporous material with the same lattice parameters. The nanoporous material selectively binds cations from aqueous solution, with selectivity for sodium and potassium ions over lithium and barium ions, as shown with FT-IR. Binding is also quantified gravimetrically with a quartz crystal microbalance with dissipation monitoring, a technique that is used for this purpose for the first time here.\u3c/p\u3

Cucurbituril-mediated immobilization of fluorescent proteins on supramolecular biomaterials

\u3cp\u3eThe reversThe reversible introduction of functionality at material surfaces is of interest for the development of functional biomaterials. In particular, the use of supramolecular immobilization strategies facilitates mild reaction and processing conditions, as compared to other covalent analogues. Here, the engineering of multicomponent supramolecular materials, beyond the use of a single supramolecular entity is proposed. Cucurbit[8]uril (Q8) mediated host–guest chemistry is combined with hydrogen bonding supramolecular 2-ureido-4-pyrimidinone (UPy)-based materials. The modular incorporation of a UPy-additive that presents one guest to incorporate into the Q8 host allows for selective supramolecular functionalization at the water–polymer material interface. Supramolecular ternary complex formation at the material surface was studied by X-ray photoelectron spectroscopy, which as a result of large overlap in atomic composition of the different components showed minor changes is surface composition upon complex formation. Surface MALDI-ToF MS measurements revealed useful insights in the formation of complexes. Protein immobilization was monitored using both fluorescence spectroscopy and quartz crystal microbalance with dissipation monitoring, which successfully demonstrated ternary complex formation. Although proteins could selectively be immobilized onto the surfaces, control of the system's stability remains a challenge as a result of the dynamicity of the host–guest assembly. ible introduction of functionality at material surfaces is of interest for the development of functional biomaterials. In particular, the use of supramolecular immobilization strategies facilitates mild reaction and processing conditions, as compared to other covalent analogues. Here, the engineering of multicomponent supramolecular materials, beyond the use of a single supramolecular entity is proposed. Cucurbit[8]uril (Q8) mediated host-guest chemistry is combined with hydrogen bonding supramolecular 2-ureido-4-pyrimidinone (UPy)-based materials. The modular incorporation of a UPy-additive that presents one guest to incorporate into the Q8 host allows for selective supramolecular functionalization at the water-polymer material interface. Supramolecular ternary complex formation at the material surface was studied by X-ray photoelectron spectroscopy, which as a result of large overlap in atomic composition of the different components showed minor changes is surface composition upon complex formation. Surface MALDI-ToF MS measurements revealed useful insights in the formation of complexes. Protein immobilization was monitored using both fluorescence spectroscopy and quartz crystal microbalance with dissipation monitoring, which successfully demonstrated ternary complex formation. Although proteins could selectively be immobilized onto the surfaces, control of the system's stability remains a challenge as a result of the dynamicity of the host-guest assembly.\u3c/p\u3

From supramolecular polymers to multi-component biomaterials

\u3cp\u3eThe most striking and general property of the biological fibrous architectures in the extracellular matrix (ECM) is the strong and directional interaction between biologically active protein subunits. These fibers display rich dynamic behavior without losing their architectural integrity. The complexity of the ECM taking care of many essential properties has inspired synthetic chemists to mimic these properties in artificial one-dimensional fibrous structures with the aim to arrive at multi-component biomaterials. Due to the dynamic character required for interaction with natural tissue, supramolecular biomaterials are promising candidates for regenerative medicine. Depending on the application area, and thereby the design criteria of these multi-component fibrous biomaterials, they are used as elastomeric materials or hydrogel systems. Elastomeric materials are designed to have load bearing properties whereas hydrogels are proposed to support in vitro cell culture. Although the chemical structures and systems designed and studied today are rather simple compared to the complexity of the ECM, the first examples of these functional supramolecular biomaterials reaching the clinic have been reported. The basic concept of many of these supramolecular biomaterials is based on their ability to adapt to cell behavior as a result of dynamic non-covalent interactions. In this review, we show the translation of one-dimensional supramolecular polymers into multi-component functional biomaterials for regenerative medicine applications.\u3c/p\u3

Supramolecular loop stitches of discrete block molecules on graphite:tunable hydrophobicity by naphthalenediimide end-capped oligodimethylsiloxane

\u3cp\u3eThe noncovalent functionalization of surfaces has gained widespread interest in the scientific community, and it is progressively becoming an extremely productive research field offering brand new directions for both supramolecular and materials chemistry. As the end-groups often play a dominant role in the surface properties obtained, creating loops with end-groups only at the surface will lead to unexpected architectures and hence properties. Here we report the self-assembly of discrete block molecules - structures in-between block copolymers and liquid crystals - featuring oligodimethylsiloxanes (ODMS) end-capped with naphthalenediimides (NDIs) at the 1-phenyloctane/highly oriented pyrolytic graphite (1-PO/HOPG) interface. These structures produce unprecedented vertically nanophase-separated monolayers featuring NDI moieties that regularly arrange on the HOPG surface, while the highly dynamic ODMS segments form loops above them. Such arrangement is preserved upon drying and generates hydrophobic HOPG substrates in which the ODMS block length tunes the hydrophobicity. Thus, the exact structural fidelity of the discrete macromolecules allows for the correlation of nanoscopic organization with macroscopic properties of the self-assembled materials. We present a general strategy for tunable hydrophobic coatings on graphite based on molecularly combining crystalline aromatic moieties and immiscible oligodimethylsiloxanes.\u3c/p\u3

Computationally designed 3D printed self-expandable polymer stents with biodegradation capacity for minimally invasive heart valve implantation:A proof-of-concept study

\u3cp\u3eThe evolution of minimally invasive implantation procedures and the in vivo remodeling potential of decellularized tissue-engineered heart valves require stents with growth capacity to make these techniques available for pediatric patients. By means of computational tools and 3D printing technology, this proof-of-concept study demonstrates the design and manufacture of a polymer stent with a mechanical performance comparable to that of conventional nitinol stents used for heart valve implantation in animal trials. A commercially available 3D printing polymer was selected, and crush and crimping tests were conducted to validate the results predicted by the computational model. Finally, the degradability of the polymer was assessed via accelerated hydrolysis.\u3c/p\u3

The sequence-specific cellular uptake of spherical nucleic acid nanoparticle conjugates

The sequence-dependent cellular uptake of spherical nucleic acid nanoparticle conjugates (SNAs) is investigated. This process occurs by interaction with class A scavenger receptors (SR-A) and caveolae-mediated endocytosis. It is known that linear poly(guanine) (poly G) is a natural ligand for SR-A, and it has been proposed that interaction of poly G with SR-A is dependent on the formation of G-quadruplexes. Since G-rich oligonucleotides are known to interact strongly with SR-A, it is hypothesized that SNAs with higher G contents would be able to enter cells in larger amounts than SNAs composed of other nucleotides, and as such, cellular internalization of SNAs is measured as a function of constituent oligonucleotide sequence. Indeed, SNAs with enriched G content show the highest cellular uptake. Using this hypothesis, a small molecule (camptothecin) is chemically conjugated with SNAs to create drug-SNA conjugates and it is observed that poly G SNAs deliver the most camptothecin to cells and have the highest cytotoxicity in cancer cells. Our data elucidate important design considerations for enhancing the intracellular delivery of spherical nucleic acids

Efficient functionalization of additives at supramolecular material surfaces

Selective surface modification reactions can be performed on additives that are supramolecularly incorporated into supramolecular materials. Hereby, processing of the material, that regularly requires harsh processing conditions (i.e., the use of organic solvents and/or high temperatures), and functionalization can be decoupled. Moreover, high-resolution depth profiling by time-of-flight (ToF) secondary-ion mass spectrometry clearly shows distinct differences in surface and bulk material composition

Modulation of macrophage phenotype and protein secretion via heparin-IL-4 functionalized supramolecular elastomers

\u3cp\u3eHallmark of the in situ tissue engineering approach is the use of bioresorbable, synthetic, acellular scaffolds, which are designed to modulate the inflammatory response and actively trigger tissue regeneration by the body itself at the site of implantation. Much research is devoted to the design of synthetic materials modulating the polarization of macrophages, which are essential mediators of the early stages of the inflammatory response. Here, we present a novel method for the functionalization of elastomers based on synthetic peptide chemistry, supramolecular self-assembly, and immobilization of heparin and interleukin 4 (IL-4), which is known to skew the polarization of macrophages into the wound healing M2 phenotype. Ureido-pyrimidinone (UPy)-modified chain extended polycaprolactone (CE-UPy-PCL) was mixed with a UPy-modified heparin binding peptide (UPy-HBP) to allow for immobilization of heparin, and further functionalization with IL-4 via its heparin binding domain. As a first proof of principle, CE-UPy-PCL and UPy-HBP were premixed in solution, dropcast and exposed to primary human monocyte-derived macrophages, in the presence or absence of IL-4-heparin functionalization. It was demonstrated that the supramolecular IL-4-heparin functionalization effectively promoted macrophage polarization into an anti-inflammatory phenotype, in terms of morphology, immunohistochemistry and cytokine secretion. Moreover, the supramolecular functionalization approach used was successfully translated to 3D electrospun scaffolds for in situ tissue engineering purposes, where UPy-HBP retention, and heparin and IL-4 attachment to the supramolecular scaffolds were proven over 7 days. Lastly, human monocyte-derived macrophages were cultured on 3D scaffolds, which, in case of IL-4-heparin functionalization, were proven to promote of an anti-inflammatory environment on protein level. This study presents a novel method in designing a versatile class of functionalized elastomers that effectively harness the anti-inflammatory behavior of macrophages in vitro, and as such, may be instrumental for the development of a new class of synthetic materials for in situ tissue engineering purposes.\u3c/p\u3e\u3cp\u3eSTATEMENT OF SIGNIFICANCE: Macrophages and their phenotypic and functional plasticity play a pivotal role in metabolic homeostasis and tissue repair. Based on this notion, bioactivated materials modulating macrophage polarization were extensively investigated in the past. Here, we designed immunomodulating, synthetic materials based on supramolecular immobilization of a heparin binding peptide, and further bioactivation with heparin and IL-4, an anti-inflammatory cytokine responsible for M2 activation and polarization. Human monocyte-derived macrophages cultured on heparin-IL-4 bioactivated materials displayed an elongated morphology and an anti-inflammatory phenotype, with downregulation of pro-inflammatory cytokines and promotion of anti-inflammatory cytokines over time. This study represents the first step in designing a novel class of synthetic, bioactivated materials that harness the regenerative behavior of host macrophages towards in situ tissue regeneration.\u3c/p\u3