Antimicrobial peptide modification of biomaterials using supramolecular additives

Biomaterials based on non‐active polymers functionalized with antimicrobial agents by covalent modification or mixing are currently regarded as high potential solutions to prevent biomaterial associated infections that are major causes of biomedical device failure. Herewith a strategy is proposed in which antimicrobial materials are prepared by simply mixing‐and‐matching of ureido‐pyrimidinone (UPy) based supramolecular polymers with antimicrobial peptides (AMPs) modified with the same UPy‐moiety. The N‐terminus of the AMPs was coupled in solution to an UPy‐carboxylic acid synthon resulting in formation of a new amidic bond. The UPy‐functionalization of the AMPs did not affect their secondary structure, as proved by circular dichroism spectroscopy. The antimicrobial activity of the UPy‐AMPs in solution was also retained. In addition, the incorporation of UPy‐AMPs into an UPy‐polymer was stable and the final material was biocompatible. The addition of 4 mol % of UPy‐AMPs in the UPy‐polymer material protected against colonization by Escherichia coli, and methicillin‐sensitive and ‐resistant strains of Staphylococcus aureus. This modular approach enables a stable but dynamic incorporation of the antimicrobial agents, allowing at the same time for the possibility to change the nature of the polymer, as well as the use of AMPs with different activity spectra. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1926–1934     

Multiwalled carbon nanotube-doxorubicin supramolecular complexes for cancer therapeutics

Multiwalled carbon nanotube aqueous dispersions using block copolymers are able to form supramolecular complexes with the aromatic chromophore and anticancer agent doxorubicin via pi-pi stacking and enhance its cytotoxic activity.     

Preface to the special issue: Macrocyclic and supramolecular chemistry

The 14th Conference of Macrocyclic Chemistry and the 6th Conference of Supramolecular Chemistry was held in Northwest Normal University in Lanzhou, Gansu     

Cucurbituril‐mediated immobilization of fluorescent proteins on supramolecular biomaterials

The 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. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3607–3616     

Carrier-free supramolecular nanomedicines assembled by small-molecule therapeutics for cancer treatment

Nanomedicines have shown great promise in cancer therapy, but are challenged by limited drug loading, safety concerns of drug carriers, and complexity of function integration. Recently, carrier-free nanomedicines produced by supramolecular assembly of small-molecule therapeutic functionalities and their conjugates were proposed to address these issues. These nanomedicines achieve very high drug loading, enhanced tumor accumulation and improved therapeutic efficiency, and avoid carrier-related sa...     

Macrocyclic aromatic ether-imide-sulfones: versatile supramolecular receptors with extreme thermochemical and oxidative stability

Macrocyclic receptors having extreme thermo-oxidative stability, and which bind a wide range of electron-donor substrates via pi-stacking donor-acceptor interactions, are accessible by cycloimidization of an amine-functionalized aryl ether-sulfone with pyromellitic dianhydride or 1,4,5,8-naphthalenetetracarboxylic dianhydride. The potential of these receptors in supramolecular chemistry is illustrated, for example, by the spontaneous self-assembly and crystallization of a five-component [3]pseudorotaxane from a solution of its constituents.     

Photo gel-sol/sol-gel transition and its patterning of a supramolecular hydrogel as stimuli-responsive biomaterials

In a focused library of glycolipid-based hydrogelators bearing fumaric amide as a trans-cis photoswitching module, several new photoresponsive supramolecular hydrogelators were discovered, the gel-sol/sol-gel transition of which was pseudo-reversibly induced by light. Studying the optimal hydrogel by NMR spectroscopy and various microscopy techniques showed that the trans-cis photoisomerization of the double bond of the fumaric amide unit effectively caused assembly or disassembly of the self-assembled supramolecular fibers to yield the macroscopic hydrogel or the corresponding sol, respectively. The entanglement of the supramolecular fibers produced nanomeshes, the void space of which was roughly evaluated to be 250 nm based on confocal laser scanning microscopy observations of the size-dependent Brownian motion of nanobeads embedded in the supramolecular hydrogel. It was clearly shown that such nanomeshes become a physical obstacle that captures submicro- to micrometer-sized substrates such as beads or bacteria. By exploiting the photoresponsive property of the supramolecular nanomeshes, we succeeded in off/on switching of bacterial movement and rotary motion of bead-tethered F(1)-ATPase, a biomolecular motor protein, in the supramolecular hydrogel. Furthermore, by using the photolithographic technique, gel-sol photopatterning was successfully conducted to produce sol spots within the gel matrix. The fabricated gel-sol pattern not only allowed regulation of bacterial motility in a limited area, but also off/on switching of F1-ATPase rotary motion at the single-molecule level. These results demonstrated that the photoresponsive supramolecular hydrogel and the resulting nanomeshes may provide unique biomaterials for the spatiotemporal manipulation of various biomolecules and live bacteria.     

Construction of supramolecular helical nanofibers using renewable biomaterials: self-assembly of a cytidylic acid-appended bolaamphiphile in lemon juice

We performed the self-assembly of a 1,18-cytidylic acid-appended bolaamphiphile (C18C) in lemon juice, which contained citric acid, and succeeded in forming left-handed helical nanofibers with diameters, lengths, and pitches of ca. 6-7 nm, several hundred nm to 5 μm, and ca. 30-40 nm, respectively.     

Enzymatic activity at the surface of biomaterials via supramolecular anchoring of peptides: the effect of material processing

Supramolecular polymers allow for a modular approach to bioactive biomaterials. Here the effect of processing on the bioactivation of supramolecular biomaterials using a RNase S assay is investigated. Incorporation of S-peptides into supramolecular polymers by solvent casting shows a clear organic-solvent dependency. Although a significant release of the S-peptides is observed, RNase S activity can be measured indicating successful S-peptide surface immobilization. Additionally, the effect of electrospinning on the biomaterial's bioactivity is studied, showing that the fibrous meshes developed were bioactive. The results show the importance of solvent choice, and illustrate the potency of rendering supramolecular biomaterial films and meshes bioactive via a modular approach.     

Macrocyclic amidoacylhydrazones

Substituted dibenzo[d,j][1,2,6,9,13,14]hexaazahexadeca-2,4,10,12-tetraene-7,8-15,16-tetraones have been obtained from hydrazones of ortho-acyltosylanilines. The structure of the former has been demonstrated by IR, PMR, and mass spectra and by alternative synthesis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–995, July, 1985.     

Macrocyclic Imidazolylboranes

Cycles, not chains: 1-imidazolylboranes exist in polymeric form as a consequence of donor/acceptor interactions. Through the use of suitable substituents and under high dilution tetrameric and pentameric macrocyclic imidazolylboranes were synthesized. The picture shows the structure of the tetrameric 4,5-dimethylimidazolylborane (black: C, gray: B, white: N).     

Macrocyclic Ligands in Separations

The selectivity of macrocyclic ligands such as crown ethers and cryptands in binding metal and other cations in aqueous and nonaqueous solvents can be exploited to make ion separations. Cations are usually separated by direct interaction with the ligand. In addition, anions associated with the positively charged macrocyclic complexes can be separated in novel separations systems. We have incorporated macrocyclic ligands into high performance ion chromatography, liquid membranes, and solvent extraction separation systems involving coalescence extraction.     

Macrocyclic extractants

Interest in organic macrocycles as highly selective analytical reagents is growing. Oxygen-containing crown ethers have already been extensively studied as extractants. In addition, nitrogen- and sulphur-containing macrocycles, as well as crown ethers with chromogenic groups, are now being developed.     

Macrocyclic Ammonio-N-nitroimines

Condensation of 4,5-bis(chloromethyl)-1-methyl-1,2,3-triazole with polyethylene glycols and polyethylenepolyamines gave crown-ethers and azacrown compounds which were converted into the corresponding N-nitroimines.     

Macrocyclic conjugation pathways in porphyrins

Macrocyclic aromaticity is the most important concept in porphyrinoid chemistry. Bond resonance energy (BRE) for any pi-bond linking adjacent pyrrolic or other rings represents the stabilization energy due to macrocyclic aromaticity. We found that a main conjugation pathway associated with macrocyclic aromaticity can be traced by choosing a pi-bond with a larger BRE at every bifurcation of the pi-network. All pi-bonds located along the main conjugation pathway are intensified with large positive BREs compared with those located along the bypasses. On the other hand, a main destabilization pathway associated with macrocyclic antiaromaticity can be traced by choosing a pi-bond with a smaller BRE at every bifurcation of the pi-network. Macrocyclic conjugation pathways thus determined are fully consistent with the chemical shifts of protons attached to the macrocycle.     

Dentin-desensitizing biomaterials

Dentin hypersensitivity (DH) associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration. Medication, filling repair, laser irradiation, crown therapy, and desensitizing toothpaste are standard clinical treatment strategies, but unsatisfactory treatment modalities are marked by long-term administration, poor dentinal tubule closure, microleakage, and the development of secondary caries. To improve the treatment efficiency of DH, numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization. Biomaterials are expected to participate in dental remineralization to achieve desensitization. This review discusses various biomaterials for DH therapy based on different desensitization mechanisms, including dentinal tubule closure and dental nerve blockade, and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.     

大环聚硅氧烷分子

聚硅氧烷是一种重要的高分子材料,其优良的物理化学性能使其在化工、冶金、建筑等众多领域具有广泛的应用,由于缺少链端基,环状聚硅氧烷这种特殊的空间结构使其具有尤为特定的性质和应用性能.本文主要简述了环状聚硅氧烷相比一般线形聚硅氧烷所具有的本体、溶液和化学特性.因为聚二甲基硅氧烷是硅氧烷中最主要的一种,所以本文主要对大环聚二甲基硅氧烷的合成方法和基本性质进行了综述,并介绍了大环聚硅氧烷的应用方向,主要是在拓扑嵌入、形成索烃和聚轮烷等方面的应用.     

Macrocyclic paracyclophane synthesis

Macrocyclic stilbene derivatives are prepared using strong base to couple the terminal carbons of 1,12-bis-[4-chloromethylphenyl]-dodecane and its homologs.