Nanoparticles produced by ring-opening metathesis polymerization using norbornenyl-poly(ethylene oxide) as a ligand-free generic platform for highly selective in vivo tumor targeting

Red Light-Emitting Water-Soluble Luminescent Iridium-Containing Polynorbornenes: Synthesis, Characterization and Oxygen Sensing Properties in Biological Tissues In Vivo

New water-soluble polynorbornenes P1-P4 containing oligoether, amino acid groups and luminophoric complexes of iridium(III) were synthesized by ring-opening metathesis polymerization. The polymeric products in organic solvents and in water demonstrate intense photoluminescence in the red spectral region. The polymers P1 and P3 with 1-phenylisoquinoline cyclometalating ligands in iridium fragments reveal 4-6 fold higher emission quantum yields in solutions than those of P2 and P4 that contain iridium complexes with 1-(thien-2-yl)isoquinoline cyclometalating ligands. The emission parameters of P1-P4 in degassed solutions essentially differ from those in the aerated solutions showing oxygen-dependent quenching of phosphorescence. Biological testing of P1 and P3 demonstrates that the polymers do not penetrate into live cultured cancer cells and normal skin fibroblasts and do not possess cytotoxicity within the concentrations and time ranges reasonable for biological studies. In vivo, the polymers display longer phosphorescence lifetimes in mouse tumors than in muscle, as measured using phosphorescence lifetime imaging (PLIM), which correlates with tumor hypoxia. Therefore, preliminary evaluation of the synthesized polymers shows their suitability for noninvasive in vivo assessments of oxygen levels in biological tissues.

Supramolecular behaviour and fluorescence of rhodamine-functionalised ROMP polymers

A ROMP platform leading to rhodamine B containing amphiphilic block copolymers, which self-assemble into micelles which are able to sequester molecular dyes and interact with them by energy transfer. The polymer micelles do not interact with DNA.

Epigenetic Metalloenzymes

Epigenetics controls the expression of genes and is responsible for cellular phenotypes. The fundamental basis of these mechanisms involves in part the post-translational modifications (PTMs) of DNA and proteins, in particular, the nuclear histones. DNA can be methylated or demethylated on cytosine. Histones are marked by several modifications including acetylation and/or methylation, and of particular importance are the covalent modifications of lysine. There exists a balance between addition and removal of these PTMs, leading to three groups of enzymes involved in these processes: the writers adding marks, the erasers removing them, and the readers able to detect these marks and participating in the recruitment of transcription factors. The stimulation or the repression in the expression of genes is thus the result of a subtle equilibrium between all the possibilities coming from the combinations of these PTMs. Indeed, these mechanisms can be deregulated and then participate in the appearance, development and maintenance of various human diseases, including cancers, neurological and metabolic disorders. Some of the key players in epigenetics are metalloenzymes, belonging mostly to the group of erasers: the zinc-dependent histone deacetylases (HDACs), the iron-dependent lysine demethylases of the Jumonji family (JMJ or KDM) and for DNA the iron-dependent ten-eleven-translocation enzymes (TET) responsible for the oxidation of methylcytosine prior to the demethylation of DNA. This review presents these metalloenzymes, their importance in human disease and their inhibitors.

The ROMP: A Powerful Approach to Synthesize Novel pH-Sensitive Nanoparticles for Tumor Therapy

Fast clearance, metabolism, and systemic toxicity are major limits for the clinical use of anti-cancer drugs. Histone deacetylase inhibitors (HDACi) present these defects, despite displaying promising anti-tumor properties on tumor cells in vitro and in in vivo models of cancer. The specific delivery of anti-cancer drugs into the tumor should improve their clinical benefit by limiting systemic toxicity and by increasing the anti-tumor effect. This paper deals with the synthesis of the polymeric nanoparticle platform, which was produced by Ring-Opening Metathesis Polymerization (ROMP), able to release anti-cancer drugs in dispersion, such as histone deacetylase inhibitors, into mesothelioma tumors. The core-shell nanoparticles (NPs) have stealth properties due to their poly(ethylene oxide) shell and can be viewed as universal nano-carriers on which any alkyne-modified anti-cancer molecule can be grafted by click chemistry. A cleavage reaction of the chemical bond between NPs and drugs through the contact of NPs with a medium presenting an acidic pH, which is typically a cancer tumor environment or an acidic intracellular compartment, induces a controlled release of the bioactive molecule in its native form. In our in vivo syngeneic model of mesothelioma, a highly selective accumulation of the particles in the tumor was obtained. The release of the drugs led to an 80% reduction of tumor weight for the best compound without toxicity. Our work demonstrates that the use of theranostic nanovectors leads to an optimized delivery of epigenetic inhibitors in tumors, which improves their anti-tumor properties in vivo.

Thermosensitive polynorbornene poly(ethylene oxide) nanoparticles loaded with oligoDNAs: an innovative approach for acting on cancer-associated pain

DNA oligonucleotides (oligoDNAs) have been recently identified as a novel class of therapeutic tools for acting on the cancer-associated pain.

Fluorescent ROMP Monomers and Copolymers for Biomedical Applications

The synthesis and characterization of a series of green, blue and red-fluorescent exo-oxanorbornene acid and imide monomers carrying nitrobenzofurazan, coumarin, and Rhodamin B, respectively, as fluorophores is presented. These monomers carry oxanorbornene as polymerizable unit, and were readily copolymerized with bioactive functional oxanorbornene monomers by ring-opening metathesis polymerization (ROMP), as demonstrated by gel permeation chromatography and NMR spectroscopy. Due to the ease of synthesis of these monomers, and their cost-effectiveness compared many to other fluorescent probes, they are useful for biomaterials applications.

Synthesis, Characterization and Thermal Properties of Poly(ethylene oxide), PEO, Polymacromonomers via Anionic and Ring Opening Metathesis Polymerization

Branched polymers are a valuable class of polymeric materials. In the present study, anionic polymerization techniques were employed for the synthesis of low molecular weight poly(ethylene oxide) (PEO) macromonomers bearing norbornenyl end groups. The macromonomers were characterized by SEC, MALDI-TOF and NMR spectroscopy. Subsequent ring opening metathesis polymerization (ROMP) of the macromonomers using ruthenium catalysts (Grubbs catalysts of the 1st, 2nd and 3rd generations) afforded the corresponding polymacromonomers. The effects of the macromonomer molecular weight, the type of the catalyst, the nature of the solvent, the monomer concentration and the polymerization temperature on the molecular characteristics of the branched polymers were examined in detail. The crystallization behavior of the macromonomers and the corresponding polymacromonomers were studied by Differential Scanning Calorimetry (DSC). The thermal stability and the kinetics of the thermal decomposition of the samples were also studied by Thermogravimetric Analysis (TGA). The activation energies of the thermal decomposition were analyzed using the Ozawa–Flynn–Wall and Kissinger methodologies.

Histone Deacetylase Inhibitors Delivery using Nanoparticles with Intrinsic Passive Tumor Targeting Properties for Tumor Therapy

Fast clearance, metabolism and systemic toxicity are major limits for the clinical use of anti-cancer drugs. Histone deacetylase inhibitors (HDACi) present these defects despite displaying promising anti-tumor properties on tumor cells in vitro and in in vivo model of cancers. Specific delivery of anti-cancer drugs into the tumor should improve their clinical benefit by limiting systemic toxicity and by increasing the anti-tumor effect. In this work, we describe a simple and flexible polymeric nanoparticle platform highly targeting the tumor in vivo and triggering impressive tumor weight reduction when functionalized with HDACi. Our nanoparticles were produced by Ring-Opening Metathesis Polymerization of azido-polyethylene oxide-norbornene macromonomers and functionalized using click chemistry. Using an orthotopic model of peritoneal invasive cancer, a highly selective accumulation of the particles in the tumor was obtained. A combination of epigenetic drugs involving a pH-responsive histone deacetylase inhibitor (HDACi) polymer conjugated to these particles gave 80% reduction of tumor weight without toxicity whereas the free HDACi has no effect. Our work demonstrates that the use of a nanovector with theranostic properties leads to an optimized delivery of potent HDACi in tumor and then, to an improvement of their anti-tumor properties in vivo.

Vancomycin Functionalized Nanoparticles for Bactericidal Biomaterial Surfaces

In this paper, we describe a simple and powerful way to synthesize antibacterial biomaterials with applications as implants in orthopedic surgery. Such implants are obtained by covalently grafting onto the Ti90A16 V4 alloy surface with vancomycin-functionalized nanoparticles. Nanoparticles were produced by ring-opening metathesis polymerization of α-norbornenyl-ω-vancomycin poly(ethylene oxide) macromonomers. Vancomycin is an interesting candidate because of its use in the field of implant associated infection as it is a glycopeptide which acts on bacterial walls. As a consequence, vancomycin does not need to be released for it to be active. In the first part of this paper, the synthesis and the complete characterization of these materials are described. In a second part, the in vitro antibacterial behavior is analyzed and discussed.

Modular Design of Poly(norbornenes) for Organelle-Specific Imaging in Tumor Cells

Through modular ROMP (ring-opening metathesis polymerization) directly from monomeric norbornenes of bioactive peptides, rhodamine B chromophore, and PEG solubilizer, we designed and synthesized a series of water-soluble poly(norbornenes) with organelle-specific imaging capability in tumor cells. For the selection of FxrFxK, TAT, and SV40 peptide sequences, these fluorescence probes exhibited different targeting specificity toward mitochondria, lysosome, and nucleolus, respectively, based on the same poly(norbornene) backbonds. More importantly, the ROMP strategy enables selective combination from various monomers and allows programmable biofunctionalization via peptide sequence permutations, which would greatly extend the biomedical applications such as imaging, diagnosis, and therapy for these synthetic polymers.

Switchable two-photon imaging of RGD-functionalized polynorbornenes with enhanced cellular uptake in living cells

Two-photon imaging polynorbornenes were fabricated directly from photochromic spiropyran, RGD peptides and hydrophilic PEG monomers via modular ROMP.

Editorial of Special Issue Ruthenium Complex: The Expanding Chemistry of the Ruthenium Complexes

Recent trends in Ru complex chemistry are surveyed with emphasis on the development of anticancer drugs and applications in catalysis, polymers, materials science and nanotechnology.

Redox-responsive branched-bottlebrush polymers for in vivo MRI and fluorescence imaging

Stimuli-responsive multimodality imaging agents have broad potential in medical diagnostics. Herein, we report the development of a new class of branched-bottlebrush polymer dual-modality organic radical contrast agents--ORCAFluors--for combined magnetic resonance and near-infrared fluorescence imaging in vivo. These nitroxide radical-based nanostructures have longitudinal and transverse relaxation times that are on par with commonly used heavy-metal-based magnetic resonance imaging (MRI) contrast agents. Furthermore, these materials display a unique compensatory redox response: fluorescence is partially quenched by surrounding nitroxides in the native state; exposure to ascorbate or ascorbate/glutathione leads to nitroxide reduction and a concomitant 2- to 3.5-fold increase in fluorescence emission. This behaviour enables correlation of MRI contrast, fluorescence intensity and spin concentration with tissues known to possess high concentrations of ascorbate in mice. Our in vitro and in vivo results, along with our modular synthetic approach, make ORCAFluors a promising new platform for multimodality molecular imaging.

Vorinostat-polymer conjugate nanoparticles for Acid-responsive delivery and passive tumor targeting

In vivo histone deacetylase (HDAC) inhibition by vorinostat under clinically acceptable dosing is limited by its poor pharmacokinetics properties. A new type of nontoxic pH-responsive delivery system has been synthesized by ring-opening metathesis polymerization, allowing for the selective distribution of vorinostat in mesothelioma tumors in vivo and subsequent histone reacetylation. The delivery system is synthesized by generic click chemistry, possesses native stealth properties for passive tumor targeting, and does not need additional chemistry for cellular internalization. Although vorinostat alone at 50 mg/kg in mice showed no effect, our new delivery system with 2 mg/kg vorinostat promoted histone reacetylation in tumors without side effects, demonstrating that our strategy improves the activity of this HDAC inihibitor in vivo.

A modular designed copolymer with anti-thrombotic activity and imaging capability

Through a modular ROMP (ring-opening metathesis polymerization) strategy, a random copolymer with anti-thrombotic activity and imaging capability has been constructed from RGD, rhodamine B and PEG modified norbornene monomers. As we expected, these tri-component polynorbornenes exhibit significant enhancement in anti-thrombotic efficacy and bioavailability in vivo.