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21.
Davila J Chassepot A Longo J Boulmedais F Reisch A Frisch B Meyer F Voegel JC Mésini PJ Senger B Metz-Boutigue MH Hemmerlé J Lavalle P Schaaf P Jierry L 《Journal of the American Chemical Society》2012,134(1):83-86
Cell adhesion processes take place through mechanotransduction mechanisms where stretching of proteins results in biological responses. In this work, we present the first cyto-mechanoresponsive surface that mimics such behavior by becoming cell-adhesive through exhibition of arginine-glycine-aspartic acid (RGD) adhesion peptides under stretching. This mechanoresponsive surface is based on polyelectrolyte multilayer films built on a silicone sheet and where RGD-grafted polyelectrolytes are embedded under antifouling phosphorylcholine-grafted polyelectrolytes. The stretching of this film induces an increase in fibroblast cell viability and adhesion. 相似文献
22.
Johan R. Johansson Yubo Wang Dr. Mattias P. Eng Prof. Nina Kann Prof. Per Lincoln Dr. Johanna Andersson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6246-6256
The slow dissociation of DNA threading intercalators makes them interesting as model compounds in the search for new DNA targeting drugs, as there appears to be a correlation between slow dissociation and biological activity. Thus, it would be of great value to understand the mechanisms controlling threading intercalation, and for this purpose we have investigated how the length of the bridging ligand of binuclear ruthenium threading intercalators affects their DNA binding properties. We have synthesised a new binuclear ruthenium threading intercalator with slower dissociation kinetics from ct‐DNA than has ever been observed for any ruthenium complex with any type of DNA, a property that we attribute to the increased distance between the ruthenium centres of the new complex. By comparison with previously studied ruthenium complexes, we further conclude that elongation of the bridging ligand reduces the sensitivity of the threading interaction to DNA flexibility, resulting in a decreased AT selectivity for the new complex. We also find that the length of the bridging ligand affects the enantioselectivity with increasing preference for the ΔΔ enantiomer as the bridging ligand becomes longer. 相似文献
23.
Johanna Flock Dr. Amra Suljanovic Dr. Ana Torvisco Dr. Wolfgang Schoefberger Birgit Gerke Prof. Dr. Rainer Pöttgen Prof. Dr. Roland C. Fischer Prof. Dr. Michaela Flock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15504-15517
Stabilization of the central atom in an oxidation state of zero through coordination of neutral ligands is a common bonding motif in transition‐metal chemistry. However, the stabilization of main‐group elements in an oxidation state of zero by neutral ligands is rare. Herein, we report that the transamination reaction of the DAMPY ligand system (DAMPY=2,6‐[ArNH‐CH2]2(NC5H3) (Ar=C6H3‐2,6‐iPr2)) with Sn[N(SiMe3)2]2 produces the DIMPYSn complex (DIMPY=(2,6‐[ArN?CH]2(NC5H3)) with the Sn atom in a formal oxidation state of zero. This is the first example of a tin compound stabilized in a formal oxidation state of zero by only one donor molecule. Furthermore, three related low‐valent SnII complexes, including a [DIMPYSnIICl]+[SnCl3]? ion pair, a bisstannylene DAMPY{SnII[N(SiMe3)2]2}2, and the enamine complex MeDIMPYSnII, were isolated. Experimental results and the conclusions drawn are also supported by theoretical studies at the density functional level of theory and 119Sn Mössbauer spectroscopy. 相似文献
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27.
Gajewski JJ Bocian W Brichford NL Henderson JL 《The Journal of organic chemistry》2002,67(12):4236-4240
The competitive kinetics of additions of allyl to benzaldehyde-h and -d from allyltributyl tin, from diisopropyltartrylallyl boronate, and from allyl bromide and zinc dust in aqueous tetrahydrofuran have inverse secondary deuterium kinetic isotope effects, SDKIEs. These inverse SDKIEs are in contrast to the normal SDKIEs that were obtained with allyl lithium and allyl Grignard, suggesting rate-determining single-electron transfer in these cases. By various MO calculations the transition state for addition of allyl boronate occurs with substantial B-O bond formation and little C-C bond formation. The magnitudes of the SDKIEs with the other two allylating reagents, when compared with reasonable equilibrium isotope effects for the addition, suggest transition states with substantial C-C bond formation. 相似文献
28.
Photochemical switching has been studied of double-tailed phosphate amphiphiles containing azobenzene units in both tails in aqueous vesicular dispersions and in mixed vesicular systems with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). Since the ease of switching depends on the strength of the bilayer packing, particular emphasis has been placed on the occurrence of H-aggregation in the hydrophobic core of the vesicles. UV-vis spectrometry was employed to monitor H-aggregation and showed how this process depends on the ionic strength and on the mode of preparation of the vesicles. Two types of H-aggregates were observed in mixed DOPC vesicles with 5 mol % of azobenzene phosphate: one with lambda(max) at around 300 nm and one with lambda(max) at 305-320 nm. Those with lambda(max) at 300 nm could not be trans-cis photoisomerized, whereas those with lambda(max) at 305-320 nm are more loosely packed and can be photochemically switched. The permeability of the vesicular bilayers, as probed with leakage experiments using calcein as a fluorescent probe, was examined as another measure for the strength of bilayer packing. Leakage occurred only for DOPC vesicles containing more than 20 mol % of azobenzenephosphate, irradiated with UV light to induce trans-cis photoisomerization. We contend that detailed information on bilayer packing will be of crucial importance for fine-tuning the lateral pressure in vesicular membranes with the ultimate aim to steer the opening and closing of mechanosensitive protein channels of large conductance. 相似文献
29.
Earle MJ Hakala U Hardacre C Karkkainen J McAuley BJ Rooney DW Seddon KR Thompson JM Wahala K 《Chemical communications (Cambridge, England)》2005,(7):903-905
Chloroindate(III) ionic liquids are versatile reaction media for Friedel-Crafts acylation reactions; the system is catalytic and totally recyclable, using an aqueous workup, with no leaching of the indium into the product phase. 相似文献
30.
Johanna Andersson Dr. Minna Li Prof. Per Lincoln 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(36):11037-11046
The binuclear ruthenium complex [μ‐bidppz(phen)4Ru2]4+ has been extensively studied since the discovery of its unusual threading intercalation interaction with DNA, a binding mode with extremely slow binding and dissociation kinetics. The complex has been shown to be selective towards long stretches of alternating AT base pairs, which makes it interesting, for example, as a model compound for anti‐malaria drugs due to the high AT content of the genome of the malaria parasite P. falciparum. We have investigated the effect of bridging ligand structure on threading intercalation ability and found that length and rigidity as well as the size of the intercalated ring system are all factors that affect the rate and selectivity of the threading intercalation. In particular, we discovered a new DNA‐threading compound, [μ‐dppzip(phen)4Ru2]4+, which appears to be just at the border of being capable of threading intercalation and displays even greater selectivity for AT‐DNA than the parent compound, [μ‐bidppz(phen)4Ru2]4+. 相似文献