[show abstract][hide abstract] ABSTRACT: A bioorthogonal organometallic reaction is a biocompatible transformation undergone by a synthetic material exclusively through the mediation of a non-biotic metal source; a selective process used to label biomolecules and activate probes in biological environs. Here we report the in vitro bioorthogonal generation of 5-fluorouracil from a biologically inert precursor by heterogeneous Pd(0) catalysis. Although independently harmless, combined treatment of 5-fluoro-1-propargyl-uracil and Pd(0)-functionalized resins exhibits comparable antiproliferative properties to the unmodified drug in colorectal and pancreatic cancer cells. Live-cell imaging and immunoassay studies demonstrate that the cytotoxic activity of the prodrug/Pd(0)-resin combination is due to the in situ generation of 5-fluorouracil. Pd(0)-resins can be carefully implanted in the yolk sac of zebrafish embryos and display excellent biocompatibility and local catalytic activity. The in vitro efficacy shown by this masking/activation strategy underlines its potential to develop a bioorthogonally activated prodrug approach and supports further in vivo investigations.
[show abstract][hide abstract] ABSTRACT: Telomerase comprises a reverse transcriptase and an internal RNA template that maintains telomeres in many eukaryotes, and it is a well-validated cancer target. However, there is a dearth of small molecules with efficacy against human telomerase in vivo. We developed a surrogate yeast high-throughput assay to identify human telomerase inhibitors. The reversibility of growth arrest induced by active human telomerase was assessed against a library of 678 compounds preselected for bioactivity in S. cerevisiae. Four of eight compounds identified reproducibly restored growth to strains expressing active human telomerase, and three of these four compounds also specifically inhibited purified human telomerase in vitro. These compounds represent probes for human telomerase function, and potential entry points for development of lead compounds against telomerase-positive cancers.
[show abstract][hide abstract] ABSTRACT: Variation at the 3' position of fluorescein via Suzuki-Miyaura cross-coupling with aryl and heteroaryl moieties gave a family of anthofluoresceins whose spectroscopic properties were studied. The 1-methylindole derivative gave the highest quantum yield and was observed to behave as a molecular rotor, displaying marked variations in fluorescent intensities with viscosity and offering possible application in cellular sensing and fluorescent polarisation assays.
[show abstract][hide abstract] ABSTRACT: Nucleic acids are the foundation stone of all cellular processes. Consequently, the use of DNA or RNA to treat genetic and acquired disorders (so called gene therapy) offers enormous potential benefits. The restitution of defective genes or the suppression of malignant genes could target a range of diseases, including cancers, inherited diseases (cystic fibrosis, muscular dystrophy, etc.), and viral infections. However, this strategy has a major barrier: the size and charge of nucleic acids largely restricts their transit into eukaryotic cells. Potential strategies to solve this problem include the use of a variety of natural and synthetic nucleic acid carriers. Driven by the aim and ambition of translating this promising therapeutic approach into the clinic, researchers have been actively developing advanced delivery systems for nucleic acids for more than 20 years. A decade ago we began our investigations of solid-phase techniques to construct families of novel nucleic acid carriers for transfection. We envisaged that the solid-phase synthesis of polycationic dendrimers and derivatized polyamimes would offer distinct advantages over solution phase techniques. Notably in solid phase synthesis we could take advantage of mass action and streamlined purification procedures, while simplifying the handling of compounds with high polarities and plurality of functional groups. Parallel synthesis methods would also allow rapid access to libraries of compounds with improved purities and yields over comparable solution methodologies and facilitate the development of structure activity relationships. We also twisted the concept of the solid-phase support on its head: we devised miniaturized solid supports that provided an innovative cell delivery vehicle in their own right, carrying covalently conjugated cargos (biomolecules) into cells. In this Account, we summarize the main outcomes of this series of chemically related projects.
Accounts of Chemical Research 03/2012; 45(7):1140-52. · 20.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: Current drug-discovery strategies are typically 'target-centric' and are based upon high-throughput screening of large chemical libraries against nominated targets and a selection of lead compounds with optimized 'on-target' potency and selectivity profiles. However, high attrition of targeted agents in clinical development suggest that combinations of targeted agents will be most effective in treating solid tumors if the biological networks that permit cancer cells to subvert monotherapies are identified and retargeted. Conventional drug-discovery and development strategies are suboptimal for the rational design and development of novel drug combinations. In this article, we highlight a series of emerging technologies supporting a less reductionist, more agile, drug-discovery and development approach for the rational design, validation, prioritization and clinical development of novel drug combinations.
[show abstract][hide abstract] ABSTRACT: We have developed miniaturized heterogeneous Pd(0)-catalysts (Pd(0)-microspheres) with the ability to enter cells, stay harmlessly within the cytosol and mediate efficient bioorthogonal organometallic chemistries (e.g., allylcarbamate cleavage and Suzuki-Miyaura cross-coupling). This approach is a major addition to the toolbox available for performing chemical reactions within cells. Here we describe a full protocol for the synthesis of the Pd(0)-microspheres from readily available starting materials (by the synthesis of size-controlled amino-functionalized polystyrene microspheres), as well as for their characterization (electron microscopy and palladium quantitation) and functional validation ('in solution' and 'in cytoplasm' conversions). From the beginning of the synthesis to functional evaluation of the catalytic device requires 5 d of work.
[show abstract][hide abstract] ABSTRACT: Herein we report a highly-efficient solid-phase strategy for the modular synthesis of 63 double-tailed lipid-peptide conjugates and their application in DNA delivery.
Chemical Communications 11/2011; 47(48):12774-6. · 6.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: Innate immune cell ingress into the site of inflammation is central for the efficient clearance of pathogens. However, in some circumstances the inflammatory response may become pathogenic to the host. Understanding the temporal ingress of innate immune cells is thus essential to predict both the defensive and adverse effects mediated by these cells in an infectious process and for developing novel therapeutic strategies. In this context, optical imaging has emerged as a powerful technique for the visualization of specific cellular events in preclinical models. Herein we describe a non-covalent tagging strategy to stably label innate immune cells using in vivo-traceable cell penetrating peptoids and their application in real-time imaging of cell migration in murine models, thereby providing a sensitive and cost effective way to visualize cellular recruitment in preclinical models of inflammation.
Medicinal Chemistry Communication 11/2011; 2(11):1050-1053. · 2.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: Many important intracellular biochemical reactions are modulated by transition metals, typically in the form of metalloproteins. The ability to carry out selective transformations inside a cell would allow researchers to manipulate or interrogate innumerable biological processes. Here, we show that palladium nanoparticles trapped within polystyrene microspheres can enter cells and mediate a variety of Pd(0)-catalysed reactions, such as allylcarbamate cleavage and Suzuki-Miyaura cross-coupling. The work provides the basis for the customization of heterogeneous unnatural catalysts as tools to carry out artificial chemistries within cells. Such in cellulo synthesis has potential for a plethora of applications ranging from cellular labelling to synthesis of modulators or inhibitors of cell function.
[show abstract][hide abstract] ABSTRACT: The therapeutic use of nucleic acids has long been heralded as a panacea of medicinal opportunity, a vision enhanced by the introduction of RNA interference technology. The Achilles heel of such an approach is the in vivo delivery of the desired nucleic acid into cells, a practice that lacks selectivity, safety and/or efficiency. Herein we report the safe and efficacious in vitro and in vivo delivery of nucleic acids using tripodal biodegradable cationic lipids. Toxicity reduction and transfection potency of these novel amphiphiles were addressed by designing the compounds to undergo complete intracellulardegradation thereby enhancing cargo release while minimising toxicity and potential tissue accumulation. Compounds demonstrated high-efficiency in transfecting DNA into cells both in vitro and in vivo with no signs of toxicity, thus potentially offering a safer alternative to viral transfection for gene therapy application.
Journal of Materials Chemistry 02/2011; 21(7):2154-2158. · 5.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: The need to understand cellular trafficking in vivo in situ requires the development and application of novel methodologies for cellular labeling and cell tracking. Here we applied new technologies associated with advances in molecular imaging to demonstrate the feasibility of labeling primary immune cells. We demonstrate the utility of fluorescently tagged polystyrene microspheres, MRI susceptible emulsions and cell entry peptoids. The adaptation of these labeling agents will permit cell specific delivery, diagnostic sensing and the delivery of therapeutic agents to sites of inflammation and infection.
[show abstract][hide abstract] ABSTRACT: The 3rd International Symposium on Cellular Delivery of Therapeutic Macromolecules (CDTM 2010), held on 27-29 June 2010 in Cardiff (Wales, UK), provided a comprehensive overview of the state of the art of key topics in cellular delivery of biologics. The CDTM symposium series, which is organized every 2 years by Arwyn Tomos Jones and Mark Gumbleton, is becoming an indispensable event in the calendar for many researchers interested in the field of cell delivery and an attractive opportunity to promote and transfer knowledge between research institutions and industry. This conference report will serve to summarize the proceedings presented along the 3-day symposium, which covered from the fundamental understanding of cell membranes and entrance pathways to the most innovative cell delivery vehicles and their applications.
[show abstract][hide abstract] ABSTRACT: Select Biosciences' MedChem Europe 2010 Sixth Annual Meeting, held in Munich, Germany, included topics covering new developments in the field of drug design. This conference report highlights selected presentations on fragment-based drug design, novel lipids for gene delivery carriers, protein-ligand binding and compound screening.
[show abstract][hide abstract] ABSTRACT: The synthesis and characterization of five different 9-alkyl-6-amino[1,2,3]triazolo[3,4-c]-5-azaquinoxalines is described. Due to the notable electrophilic character of the C-6 position of the [1,2,4]triazolo[3,4-c]-5-azaquinoxaline tricyclic system, SNAr amination was achieved simply by reacting the corresponding 6-chloro derivative with ammonia-saturated acetonitrile (a non-nucleophilic polar solvent) in a sealed reaction vessel, using microwave-mediated or conventional heating.
Tetrahedron Letters - TETRAHEDRON LETT. 01/2010; 51(17):2262-2264.
[show abstract][hide abstract] ABSTRACT: In the late 1980s independent work by Felgner and Behr pioneered the use of cationic materials to complex and deliver nucleic acids into eukaryotic cells. Since this time, a vast number of synthetic transfection vectors, which are typically divided into two main "transfectors", have been developed namely: (1) cationic lipids and (2) polycationic polymers. In this chapter the main synthetic approaches used for the synthesis of these compounds will be reviewed with particular attention paid to: cationic lipids and dendrimers. This review is aimed primarily at the younger audience of doctoral students and non-specialist readers.
Topics in current chemistry 01/2010; 296:15-49. · 8.46 Impact Factor