A bioinspired approach for the modulation of electroosmotic flow and protein-surface interactions in capillary electrophoresis using silylated amino-amides blocks and covalent grafting.

We explore a bioinspired approach to design tailored functionalized capillary electrophoresis (CE) surfaces based on covalent grafting for biomolecules analysis. First, the approach aims to overcome well-known common obstacles in CE protein analysis affecting considerably the CE performance (asymmetry, resolution, and repeatability) such as the unspecific adsorption on fused silica surface and the lack of control of electroosmotic flow (EOF). Then, our approach, which relies on new amino-amide mimic hybrid precursors synthesized by silylation of amino-amides (Si-AA) derivatives with 3-isocyanatopropyltriethoxysilane, aims to recapitulate the diversity of protein-protein interactions (π-π stacking, ionic, Van der Waals…) found in physiological condition (bioinspired approach) to improve the performance of CE protein analysis (electrochromatography). As a proof of concept, these silylated Si-AA (tyrosinamide silylation, serinamide silylation, argininamide silylation, leucinamide silylation, and isoglutamine silylation acid) have been covalently grafted in physiological conditions in different amount on bare fused silica capillary giving rise to a biomimetic coating and allowing both the modulation of EOF and protein-surface interactions. The analytical performances of amino-amide functionalized capillaries were assessed using lysozyme, cytochrome C and ribonuclease A and compared to traditional capillary coatings poly(ethylene oxide), poly(diallyldimethylammonium chloride), and sodium poly(styrenesulfonate). EOF, protein adsorption rate, protein retention factor k, and selectivity were determined for each coating. All results obtained showed this approach allowed to modulate the EOF, reduce unspecific adsorption, and generate specific interactions with proteins by varying the nature and the amount of Si-AA in the functionalization mixture.

Multiplexed Imaging Reveals the Spatial Relationship of the Extracellular Acidity-Targeting pHLIP with Necrosis, Hypoxia, and the Integrin-Targeting cRGD Peptide.

pH (low) insertion peptides (pHLIPs) have been developed for cancer imaging and therapy targeting the acidic extracellular microenvironment. However, the characteristics of intratumoral distribution (ITD) of pHLIPs are not yet fully understood. This study aimed to reveal the details of the ITD of pHLIPs and their spatial relationship with other tumor features of concern. The fluorescent dye-labeled pHLIPs were intravenously administered to subcutaneous xenograft mouse models of U87MG and IGR-OV1 expressing αVß3 integrins (using large necrotic tumors). The αVß3 integrin-targeting Cy5.5-RAFT-c(-RGDfK-)4 was used as a reference. In vivo and ex vivo fluorescence imaging, whole-tumor section imaging, fluorescence microscopy, and multiplexed fluorescence colocalization analysis were performed. The ITD of fluorescent dye-labeled pHLIPs was heterogeneous, having a high degree of colocalization with necrosis. A direct one-to-one comparison of highly magnified images revealed the cellular localization of pHLIP in pyknotic, karyorrhexis, and karyolytic necrotic cells. pHLIP and hypoxia were spatially contiguous but not overlapping cellularly. The hypoxic region was found between the ITDs of pHLIP and the cRGD peptide and the Ki-67 proliferative activity remained detectable in the pHLIP-accumulated regions. The results provide a better understanding of the characteristics of ITD of pHLIPs, leading to new insights into the theranostic applications of pHLIPs.

Development of Amino Acids Functionalized SBA-15 for the Improvement of Protein Adsorption.

Ordered mesoporous materials and their modification with multiple functional groups are of wide scientific interest for many applications involving interaction with biological systems and biomolecules (e.g., catalysis, separation, sensor design, nano-science or drug delivery). In particular, the immobilization of enzymes onto solid supports is highly attractive for industry and synthetic chemistry, as it allows the development of stable and cheap biocatalysts. In this context, we developed novel silylated amino acid derivatives (Si-AA-NH2) that have been immobilized onto SBA-15 materials in biocompatible conditions avoiding the use of toxic catalyst, solvents or reagents. The resulting amino acid-functionalized materials (SBA-15@AA) were characterized by XRD, TGA, EA, Zeta potential, nitrogen sorption and FT-IR. Differences of the physical properties (e.g., charges) were observed while the structural ones remained unchanged. The adsorption of the enzyme lysozyme (Lyz) onto the resulting functionalized SBA-15@AA materials was evaluated at different pHs. The presence of different functional groups compared with bare SBA-15 showed better adsorption results, for example, 79.6 nmol of Lyz adsorbed per m2 of SBA-15@Tyr compared with the 44.9 nmol/m2 of the bare SBA-15.

Sol-gel process: the inorganic approach in protein imprinting.

Proteins play a central role in the signal transmission in living systems since they are able to recognize specific biomolecules acting as cellular receptors, antibodies or enzymes, being themselves recognized by other proteins in protein/protein interactions, or displaying epitopes suitable for antibody binding. In this context, the specific recognition of a given protein unlocks a range of interesting applications in diagnosis and in targeted therapies. Obviously, this role is already fulfilled by antibodies with unquestionable success. However, the design of synthetic artificial systems able to endorse this role is still challenging with a special interest to overcome limitations of antibodies, in particular their production and their stability. Molecular Imprinted Polymers (MIPs) are attractive recognition systems which could be an alternative for the specific capture of proteins in complex biological fluids. MIPs can be considered as biomimetic receptors or antibody mimics displaying artificial paratopes. However, MIPs of proteins remains a challenge due to their large size and conformational flexibility, their complex chemical nature with multiple recognition sites and their low solubility in most organic solvents. Classical MIP synthesis conditions result in large polymeric cavities and unspecific binding sites on the surface. In this review, the potential of the sol-gel process as inorganic polymerization strategy to overcome the drawbacks of protein imprinting is highlighted. Thanks to the mild and biocompatible experimental conditions required and the use of water as a solvent, the inorganic polymerization approach better suited to proteins than organic polymerization. Through numerous examples and applications of MIPs, we proposed a critical evaluation of the parameters that must be carefully controlled to achieve sol-gel protein imprinting (SGPI), including the choice of the monomers taking part in the polymerization.

Design of PEGylated Three Ligands Silica Nanoparticles for Multi-Receptor Targeting.

The synthesis of silica nanoparticles (SiNPs) decorated on their surface with a range of various elements (e.g., ligands, drugs, fluorophores, vectors, etc.) in a controlled ratio remains a big challenge. We have previously developed an efficient strategy to obtain in one-step, well-defined multifunctional fluorescent SiNPs displaying fluorophores and two peptides ligands as targeting elements, allowing selective detection of cancer cells. In this paper, we demonstrate that additional level of controlled multifunctionality can be achieved, getting even closer to the original concept of "magic bullet", using solely sol-gel chemistry to achieve conjugation of PEG chains for stealth, along with three different ligands. In addition, we have answered the recurrent question of the surface ungrafting by investigating the stability of different siloxane linkages with the ERETIC Method (Electronic Reference to Access In Vivo Concentrations) by 19F NMR quantification. We also compared the efficiency of the hybrid silylated fluorophore covalent linkage in the core of the SiNP to conventional methods. Finally, the tumor-cell-targeting efficiency of these multi-ligand NPs on human endothelial cells (HUVEC or HDMEC) and mixed spheroids of human melanoma cells and HUVEC displaying different types of receptors were evaluated in vitro.

Benzoxaboroles: New Potent Inhibitors of the Carbonic Anhydrases of the Pathogenic Bacterium Vibrio cholerae.

A series of urea/thiourea substituted benzoxaboroles was investigated for the inhibition of the three carbonic anhydrases encoded by Vibrio cholerae (VchCAα, VchCAß, and VchCAγ). In particular, benzoxaborole derivatives were here first assayed for the inhibition of a γ-class CA, extending the panel of CA classes that benzoxaboroles efficiently target beyond α and ß. Inhibition profiles demonstrated that VchCAα was significantly more inhibited compared to VchCAγ and, in turn, more efficiently modulated than VchCAß. Among the many selective benzoxaborole ligands detected against VchCAα over the off-target hCA II, compound 18, a p-NO2-phenylthiourea derivative, even exhibited a fully selective inhibition profile against the three VchCAs over hCA II. A comprehensive ligand/target interaction study was performed in silico for all three VchCA isoforms providing the first molecular modeling investigation with inhibitors of a γ-class CA to the best of our knowledge. The present study reinforces the rationale behind the use of benzoxaboroles as innovative antibacterial agents with a new mechanism of action, furnishing suggestions for the rational design of new potent and selective inhibitors targeting V. cholerae CAs over human off-target ones.

Radiotheranostic Agent 64Cu-cyclam-RAFT-c(-RGDfK-)4 for Management of Peritoneal Metastasis in Ovarian Cancer.

PURPOSE: Ovarian cancer peritoneal metastases (OCPMs) are a pathophysiologically heterogeneous group of tumors that are rarely curable. αVß3 integrin (αVß3) is overexpressed on tumoral neovessels and frequently on ovarian cancer cells. Here, using two clinically relevant αVß3-positive OCPM mouse models, we studied the theranostic potential of an αVß3-specific radiopeptide, 64Cu-cyclam-RAFT-c(-RGDfK-)4 (64Cu-RaftRGD), and its intra- and intertumoral distribution in relation to the tumor microenvironment. EXPERIMENTAL DESIGN: αVß3-expressing peritoneal and subcutaneous models of ovarian carcinoma (IGR-OV1 and NIH:OVCAR-3) were established in nude mice. 64Cu-RaftRGD was administered either intravenously or intraperitoneally. We performed intratumoral distribution (ITD) studies, PET/CT imaging and quantification, biodistribution assay and radiation dosimetry, and therapeutic efficacy and toxicity studies. RESULTS: Intraperitoneal administration was an efficient route for targeting 64Cu-RaftRGD to OCPMs with excellent tumor penetration. Using the fluorescence surrogate, Cy5.5-RaftRGD, in our unique high-resolution multifluorescence analysis, we found that the ITD of 64Cu-RaftRGD was spatially distinct from, but complementary to, that of hypoxia. 64Cu-RaftRGD-based PET enabled clear visualization of multiple OCPM deposits and ascites and biodistribution analysis demonstrated an inverse correlation between tumor uptake and tumor size (1.2-17.2 mm). 64Cu-RaftRGD at a radiotherapeutic dose (148 MBq/0.357 nmol) showed antitumor activities by inhibiting tumor cell proliferation and inducing apoptosis, with negligible toxicity. CONCLUSIONS: Collectively, these results demonstrate the all-in-one potential of 64Cu-RaftRGD for imaging guided radiotherapy of OCPM by targeting both tumoral neovessels and cancerous cells. On the basis of the ITD finding, we propose that pairing αVß3- and hypoxia-targeted radiotherapies could improve therapeutic efficacy by overcoming the heterogeneity of ITD encountered with single-agent treatments.

Metal-free synthesis of imino-disaccharides and calix-iminosugars by photoinduced radical thiol-ene coupling (TEC).

Radical thiol-ene coupling was exploited for the first time to prepare imino-disaccharides and multivalent iminosugars starting from sugar thiols and iminosugar alkenes or iminosugar thiols and tetra-allylated calixarene, respectively.

Multivalent Carbonic Anhydrases Inhibitors.

Biomolecular recognition using a multivalent strategy has been successfully applied, this last decade on several biological targets, especially carbohydrate-processing enzymes, proteases, and phosphorylases. This strategy is based on the fact that multivalent interactions of several inhibitory binding units grafted on a presentation platform may enhance the binding affinity and selectivity. The zinc metalloenzymes carbonic anhydrases (CAs, EC 4.2.1.1) are considered as drug targets for several pathologies, and different inhibitors found clinical applications as diuretics, antiglaucoma agents, anticonvulsants, and anticancer agents/diagnostic tools. Their main drawback is related to the lack of isoform selectivity leading to serious side effects for all pathologies in which they are employed. Thus, the multivalent approach may open new opportunities in the drug design of innovative isoform-selective carbonic anhydrase inhibitors with biomedical applications.

Uniform intratumoral distribution of radioactivity produced using two different radioagents, 64Cu-cyclam-RAFT-c(-RGDfK-)4 and 64Cu-ATSM, improves therapeutic efficacy in a small animal tumor model.

BACKGROUND: The present study proposed a new concept for targeted radionuclide therapy (TRT) to improve the intratumoral distribution of radioactivity using two different radiopharmaceuticals. We examined the efficacy of a combination of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide-based radiopharmaceutical, 64Cu-cyclam-RAFT-c(-RGDfK-)4 (64Cu-RaftRGD, an αVß3 integrin [αVß3] tracer), and 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM, a supposed tracer for hypoxic metabolism) in a small animal tumor model. RESULTS: Mice with subcutaneous αVß3-positive U87MG glioblastoma xenografts were used. The intratumoral distribution of a near-infrared dye, Cy5.5-labeled RAFT-c(-RGDfK-)4 (Cy5.5-RaftRGD), 64Cu-RaftRGD, and 64Cu-ATSM was visualized by fluorescence imaging and autoradiography of the co-injected Cy5.5-RaftRGD with 64Cu-RaftRGD or 64Cu-ATSM at 3 h postinjection. Mice were treated with a single intravenous dose of the vehicle solution (control), 18.5 or 37 MBq of 64Cu-RaftRGD or 64Cu-ATSM, or a combination (18.5 MBq of each agent). The tumor volume, tumor cell proliferation, body weight, survival, and tumor and organ uptake of radiopharmaceuticals were assessed. It was shown that Cy5.5-RaftRGD colocalized with 64Cu-RaftRGD and could be used as a surrogate for the radioactive agent. The intratumoral distribution of Cy5.5-RaftRGD and 64Cu-ATSM was discordant and nearly complementary, indicating a more uniform distribution of radioactivity achievable with the combined use of 64Cu-RaftRGD and 64Cu-ATSM. Neither 64Cu-RaftRGD nor 64Cu-ATSM showed significant effects on tumor growth at 18.5 MBq. The combination of both (18.5 MBq each) showed sustained inhibitory effects against tumor growth and tumor cell proliferation and prolonged the survival of the mice, compared to that by either single agent at 37 MBq. Interestingly, the uptake of the combination by the tumor was higher than that of 64Cu-RaftRGD alone, but lower than that of 64Cu-ATSM alone. The kidneys showed the highest uptake of 64Cu-RaftRGD, whereas the liver exhibited the highest uptake of 64Cu-ATSM. No obvious adverse effects were observed in all treated mice. CONCLUSIONS: The combination of 64Cu-RaftRGD and 64Cu-ATSM achieved an improved antitumor effect owing to the more uniform intratumoral distribution of radioactivity. Thus, combining different radiopharmaceuticals to improve the intratumoral distribution would be a promising concept for more effective and safer TRT.

Self-assembly and chiroptical properties in supramolecular complexes of adenosine phosphates and guanidinium-bispyrene.

Supramolecular systems that respond to the hydrolysis of adenosine phosphates (APs) are attractive for biosensing and to fabricate bioinspired self-assembled materials. Here, we report on the formation of supramolecular complexes between an achiral guanidinium derivative bearing two pyrene moieties, with each of the three adenosine phosphates: AMP, ADP, and ATP. By combining results from circular dichroism spectroscopy and molecular modeling simulations, we explore the induced chirality, the dynamics of the complexes, and the interactions at play, which altogether provide insights into the supramolecular self-assembly between APs and the guanidinium-bispyrene. Finally, we identify the chiroptical signals of interest in mixtures of the guanidinium derivative with the three APs in different proportions. This study constitutes a basis to evolve toward a chiroptical detection of the hydrolysis of APs based on organic supramolecular probes.

Positron emission tomography of cerebral angiogenesis and TSPO expression in a mouse model of chronic hypoxia.

The present study aimed to examine whether positron emission tomography (PET) could evaluate cerebral angiogenesis. Mice were housed in a hypoxic chamber with 8-9% oxygen for 4, 7, and 14 days, and the angiogenic responses were evaluated with a radiotracer, 64Cu-cyclam-RAFT-c(-RGDfK-)4, which targeted αVß3 integrin and was imaged with PET. The PET imaging results showed little uptake during all of the hypoxic periods. Immunofluorescence staining of the ß3 integrin, CD61, revealed weak expression, while the microvessel density assessed by CD31 staining increased with the hypoxic duration. These observations suggest that the increased vascular density originated from other types of vascular remodeling, unlike angiogenic sprouting. We then searched for any signs of vascular remodeling that could be detected using PET. PET imaging of 11C-PK11195, a marker of the 18-kDa translocator protein (TSPO), revealed a transient increase at day 4 of hypoxia. Because the immunofluorescence of glial markers showed unchanged staining over the early phase of hypoxia, the observed upregulation of TSPO expression probably originated from non-glial cells (e.g. vascular cells). In conclusion, a transient increase in TSPO probe uptake was detected with PET at only the early phase of hypoxia, which indicates an early sign of vascular remodeling induced by hypoxia.

Biomolecular dynamic covalent polymers for DNA complexation and siRNA delivery.

Synthetic delivery systems that are described as smart are considered essential for the successful development of gene therapies. Dynamic covalent polymers (DCP) are dynamic and adaptive species that can expand and shorten their main chain in a reversible fashion. In particular, polyacylhydrazone DCPs are pH-sensitive and undergo hydrolytic dissociation at acidic pH, which is an interesting feature for gene delivery. Building upon our previous finding that cationic DCPs can complex DNA through multivalent interactions, we report here on a new generation of DCPs that incorporate modified amino acids. The covalent self-assembly through polycondensation was extended towards multifunctional DCPs combining different building blocks and different molecular dynamics. These biomolecular DCPs were found able to complex both long DNA and siRNA, and biological studies demonstrate that they are able to deliver functional siRNA in living cells. This straightforward and modular approach to the self-production of multifunctional and biomolecular DCPs as siRNA vectors can therefore constitute a stepping stone in smart gene delivery using dynamic and adaptive biodynamers.

Carbonic anhydrases from Trypanosoma cruzi and Leishmania donovani chagasi are inhibited by benzoxaboroles.

A series of 6-substituted ureido- and thioureido-benzoxaboroles were investigated as inhibitors of carbonic anhydrases from Trypanosoma cruzi (TcCA), and Leishmania donovani chagasi (LdcCA). Both enzymes were inhibited by benzoxaboroles in the micromolar range. Preferential inhibitory potency against the ß-CA LdcCA versus the α-CA TcCA was observed with submicromolar inhibitory activities. Some derivatives displayed excellent inhibitory and selectivity profile over the ubiquitous and physiological relevant human off-target hCA II. This study provides a convincing opportunity to study benzoxaborole scaffold for the design of antiprotozoan potential drugs targeting the pathogen's carbonic anhydrases.

Photomodulation of DNA-Templated Supramolecular Assemblies.

A new type of DNA ligand that contains a phosphate-binding group and a photoresponsive azobenzene moiety is reported. When the azobenzene is in trans configuration, the ligand binds to the minor groove of a double-stranded DNA, whereas it partially desorbs upon trans-cis isomerisation with light. The ability to photoswitch the ligand upon interaction with DNA is evidenced by (chir)optical signatures, and deciphered by the differences of binding geometry, stability, and dynamics of the DNA/ligand complexes for the two isomers. We exploit these properties to photomodulate DNA-templated self-assembly, through the incorporation of another π-stacking DNA ligand, which together with the photoresponsive ligand form mixed supramolecular complexes along DNA. Our study demonstrates that well-designed photoresponsive DNA binders can be used to modulate multicomponent supramolecular DNA assemblies.

Benzoxaboroles as Efficient Inhibitors of the ß-Carbonic Anhydrases from Pathogenic Fungi: Activity and Modeling Study.

A series of 6-substituted benzoxaboroles were investigated as inhibitors of the ß-class carbonic anhydrase from three pathogenic fungi (Cryptococcus neoformans, Candida glabrata, and Malassezia globosa). Independently from the nature of the substituents on the phenyl of the urea/thiourea group, all reported derivatives showed nanomolar inhibitory activities against Can2 and CgNce103 vs micromolar inhibition against MgCA. Selectivity over human CA I and CA II was noticed. The observed structure-activity relationship trends have been rationalized by modeling study of selected compounds into the active site of Can2 and MgCA. The present letter demonstrates that benzoxaborole chemotype may offer interesting opportunities for the inhibition of ß-CA from pathogenic fungi and for the development of antifungal agents with a new mechanism of action.

Polyhedral Oligomeric Silsesquioxane (POSS) Bearing Glyoxylic Aldehyde as Clickable Platform Towards Multivalent Conjugates.

The straightforward access to octafunctional "cubic" silsesquioxane platform grafter with pendant glyoxylic aldehydes is described. This clickable hybrid platform readily reacts with oxyamine or hydrazide compounds to provide, respectively, oxime and acylhydrazone conjugates, thereby offering a new and effective access from which one can elaborate multivalent systems for the targeting of biomolecules of interest.

One-Pot Self-Assembly of Peptide-Based Cage-Type Nanostructures Using Orthogonal Ligations.

The designed arrangement of biomolecular entities within monodisperse nanostructures is an important challenge toward functional biomaterials. We report herein a method for the formation of water-soluble peptide-based cages using orthogonal ligation reactions-acylhydrazone condensation and thiol-maleimide addition. The results show that using preorganized cyclic peptides and heterobifunctional spacers as building blocks and a set of orthogonal and chemoselective ligation reactions enable cage formation in one pot from six components and through eight reactions. Molecular modelling simulations reveal the structural dynamics of these structures. Finally, we exploited the reactional dynamics of the acylhydrazone by demonstrating the controlled dissociation of the cage through directed component exchange.

An oxime-based glycocluster microarray.

Carbohydrate microarrays represent powerful tools to study and detect carbohydrate-binding proteins, pathogens or cells. In this paper, we report two original oxime-based methods to prepare surfaces displaying well-defined structures and valency in a given microspot with improved recognition potency with lectins. In a first "direct" approach, fully synthetic aminooxylated glycoclusters have been coated onto aldehyde-activated SiO2 (silicium substrate doped with 50 nm thermal oxide layer). To improve the preparation of the microarray in terms of rapidity and simplicity and to provide addressable surfaces on which sugars can be linked chemoselectively as clusters at defined plots, a second "indirect" strategy has been developed using successive oxime ligation steps. In both cases, binding assays with labelled lectins have revealed more potent and selective interaction due to the clustered presentation of sugars. The observed differences of interaction have been confirmed in solution by ITC.

67Cu-Radiolabeling of a multimeric RGD peptide for αVß3 integrin-targeted radionuclide therapy: stability, therapeutic efficacy, and safety studies in mice.

OBJECTIVE: Copper-67 (Cu) is one of the most promising radionuclides for internal radiation therapy. Globally, several projects have recently been initiated for developing innovative approaches for the large-scale production of Cu. Encouraged by these, we performed Cu-radiolabeling of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide conjugate, cyclam-RAFT-c(-RGDfK-)4, which selectively targets αVß3 integrin (αVß3), the transmembrane receptor involved in tumor invasion, angiogenesis, and metastasis. We also evaluated the therapeutic potential and safety of this radiocompound. MATERIALS AND METHODS: Cu, produced through the Ni(α, p)Cu reaction, was used for the radiolabeling of cyclam-RAFT-c(-RGDfK-)4 at 70°C for 10 min. The radiolabeling efficiency and product stability were assessed using reversed-phase high-performance liquid chromatography and/or thin-layer chromatography. Mice with subcutaneous αVß3-positive U87MG-glioblastoma xenografts received a single intravenous injection of one of the following: Cu-cyclam-RAFT-c(-RGDfK-)4 (11.1 MBq), peptide control, or vehicle solution. The tumor volumes were measured, side effects were assessed in terms of body weight, routine hematology, and hepatic and renal functions, and the mouse radiation dosimetry was estimated. RESULTS: Cu-cyclam-RAFT-c(-RGDfK-)4 was produced with a radiochemical purity of 97.9±2.4% and a specific activity of 2.7±0.6 MBq/nmol and showed high in-vitro and in-vivo plasma stability. The administration of a single dose of Cu-cyclam-RAFT-c(-RGDfK-)4 resulted in significant tumor growth delay in comparison with that observed upon vehicle or peptide control administration, with an estimated tumor-absorbed dose of 0.712 Gy. No significant toxicity was observed in Cu-cyclam-RAFT-c(-RGDfK-)4-treated mice. CONCLUSION: Cu-cyclam-RAFT-c(-RGDfK-)4 would be a promising therapeutic agent for αVß3 integrin-targeted internal radiotherapy.