We synthesized a panel of unnatural base pairs whose pairing depends on hydrophobic and packing forces and identify dTPT3-dNaM, which is PCR amplified with a natural base pair-like efficiency and fidelity. In addition, the dTPT3 scaffold is uniquely tolerant of attaching a propargyl amine linker, resulting in the dTPT3PA-dNaM pair, which is amplified only slightly less well. The identification of dTPT3 represents significant progress towards developing an unnatural base pair for the in vivo expansion of an organism's genetic alphabet and for a variety of in vitro biotechnology applications where it is used to site-specifically label amplified DNA, and it also demonstrates for the first time that hydrophobic and packing forces are sufficient to mediate natural-like replication.

The transmembrane cell adhesion receptor a V b 3 integrin (a V b 3 ) has been identified as an important molecular target for cancer imaging and therapy. We have developed a tetrameric cyclic RGD (Arg-Gly-Asp) peptide-based radiotracer 64 Cu-cyclam-RAFT-c(-RGDfK-) 4 , which successfully captured a V b 3 -positive tumors and angiogenesis by PET. Here, we subsequently evaluated its therapeutic potential and side effects using an established a

As part of an ongoing effort to expand the genetic alphabet for in vitro and eventually in vivo applications, we have synthesized a wide variety of predominantly hydrophobic unnatural base pairs exemplified by d5SICS-dMMO2 and d5SICS-dNaM. When incorporated into DNA, the latter is replicated and transcribed with greater efficiency and fidelity than the former, however previous optimization efforts identified the para and methoxy-distal meta positions of dMMO2 as particularly promising for further optimization. Here, we report the stepwise optimization of dMMO2 via the synthesis and evaluation of eighteen novel para-derivatized analogs of dMMO2, followed by further derivatization and evaluation of the most promising analogs with meta substituents. Subject to size constraints, we find that para substituents can optimize replication via both steric and electronic effects and that meta methoxy groups are unfavorable while fluoro substituents can be beneficial or deleterious depending on the para substituent. In addition, we find that improvements in the efficiency of unnatural triphosphate insertion translate most directly into higher fidelity replication. Importantly, we identify multiple, unique base pair derivatives that when incorporated into DNA are well replicated. The most promising, d5SICS-dFEMO, is replicated under some conditions with greater efficiency and fidelity than d5SICS-dNaM. These results clearly demonstrate the generality of hydrophobic forces for the control of base pairing within DNA, provide a wealth of new SAR data, and importantly identify multiple new candidates for eventual in vivo evaluation.

Cu-cyclam-RAFT-c(-RGDfK-)4 would be a promising therapeutic agent for αVβ3 integrin-targeted internal radiotherapy.

Heparan sulfate co-immobilized with cRGD ligands and BMP2 on biomimetic platforms promotes BMP2mediated osteogenic differentiation

We describe the synthesis and photochemical behavior of open-ended container modules connected by a 4,4'-azobiphenyl spacer. Both trans and cis azo configurations of the host can be accessed and their binding of guest molecules was characterized by NMR methods.

There is a growing interest in isolating tumor cells from biological samples. Considering that circulating tumor cells can be rare in blood, it appears challenging to capture these cells onto a surface with high selectivity and sensitivity. In the present paper we describe the design of functionalized surfaces aiming to selectively capture tumor cells by using the RGD peptide ligand either with a tetrameric or a monomeric presentation. β-cyclodextrin-coated self-assembled monolayers were used as platforms for the binding of RGD ligands endowed with a redox ferrocene cluster as the dissociation of the inclusion complex on the surface is accounted for the release of the captured cells upon electrochemical oxidation of ferrocene. For this purpose, we determined suitable RGD densities for both monovalent and tetravalent ligand presentations. The present results indicate that the clustered RGD architecture efficiently improves the selective cell capture at a very low RGD-surface density (∼ 10 RGD/μm 2 ) in comparison with the monovalent presentation (∼ 1000 RGD/ μm 2 ). IntroductionMultivalent interactions are ubiquitously observed in biological systems for a wide range of functions including integrinmediated cell adhesion to extracellular matrix (ECM). 1 Among the integrin receptors, the α V β 3 integrin subclass has received special attention as it is involved in tumour progression such as aggressive metastatic cancer.2 Felding-Habermann et al. have shown that this receptor contributes to circulating tumour cell (CTC) arrest. 3 As cells expressing α V β 3 integrin interact with the ECM through the recognition of the ubiquitous triad sequence RGD (Arg-Gly-Asp), a series of peptides containing the RGD sequence were developed for diagnosis and tumour therapy. 4 The cyclopentapeptide derivatives were found to specifically bind the α V β 3 integrin. 5 Additionally, the multimeric presentation of RGD motifs appears to be a prerequisite for efficient integrin targeting. 6 Our group and others have shown that multimeric compounds exhibit attractive biological properties. 7 Recently, we have reported the benefit of tetrameric RGD derivatives for the near-infrared optical guided surgery of solid tumours 8 and for tumour-targeted drug delivery. Although multimeric RGD compounds show better affinity than their corresponding monomers, 7 few reports have tested how important clustered architectures are for cell binding to RGD-functionalized surfaces. Pioneering studies have demonstrated that nanoscale patterning of RGD ligand presentation significantly influences cell adhesion and spreading. 10 Those surfaces were prepared from highmolecular weight RGD-containing polymers or nanoparticles. Journal NameScheme 1 Synthesis of compounds 1 and 3. Reaction conditions: i) TFA/H2O (7:3), rt, 20 min then TFA/H2O (95:5), rt, 120 min, 44%; ii) NaIO4, H2O, rt, 20 min, 46%; iii) TFA/H2O/CH3CN (7:2:1), rt, 20 min, 42%; iv) CuSO4, THPTA, sodium ascorbate, phosphate buffer pH 7.4/DMF (6/4), 45°C, 150 min, 1: 63%, 3 :71 %. SPPS: solid-ph...

Both Gram-positive and Gram-negative pathogens or pathogen-derived components, such as staphylococcal enterotoxins (SEs) and endotoxin (LPS) exposure, activate MyD88-mediated pro-inflammatory cellular immunity for host defense. However, dysregulated MyD88-mediated signaling triggers exaggerated immune response that often leads to toxic shock and death. Previously, we reported a small molecule compound 1 mimicking BB-loop structure of MyD88 was capable of inhibiting pro-inflammatory response to SEB exposure in mice. In this study, we designed a dimeric structure compound 4210 covalently linked with compound 1 by a non-polar cyclohexane linker which strongly inhibited the production of pro-inflammatory cytokines in human primary cells to SEB (IC50 1-50 μm) or LPS extracted from Francisella tularensis, Escherichia coli, or Burkholderia mallei (IC50 10-200 μm). Consistent with cytokine inhibition, in a ligand-induced cell-based reporter assay, compound 4210 inhibited Burkholderia mallei or LPS-induced MyD88-mediated NF-kB-dependent expression of reporter activity (IC50 10-30 μm). Furthermore, results from a newly expressed MyD88 revealed that 4210 inhibited MyD88 dimer formation which is critical for pro-inflammatory signaling. Importantly, a single administration of compound 4210 in mice showed complete protection from lethal toxin challenge. Collectively, these results demonstrated that compound 4210 inhibits toxin-induced inflated pro-inflammatory immune signaling, thus displays a potential bacterial toxin therapeutic.