Nanoparticles were synthesized and modified for target drug delivery. The research involved the aqueous synthesis of near infrared (NIR) sensitive Au-Au₂S nanoparticles. An anti-cancer drug (<i>cis-platin</i>) was subsequently adsorbed onto the Au-Au₂S nanoparticle surface via the 11-mercaptoundecanoic acid layers. The results showed that the degree of adsorption of cis-platin onto Au-Au₂S nanoparticles was controlled by the pH value of solution, and the rate of drug release was sensitive to NIR irradiation. The results of the synthesis, drug-release properties and nanoparticle-cell interactions will be discussed. / Singapore-MIT Alliance (SMA)

Protein-protein interactions (PPIs) are attractive targets because of their therapeutic potential. One approach to design small molecules that can disrupt the PPIs is to use structural information of proteins. With this approach, triazole-based peptidomimetics that mimic beta-turn hot-spot regions in neurotrophins were synthesized. The monovalent mimics were assembled into bivalent mimics via a combinatorial method. Three different bivalent mimics were prepared for different studies. Bivalent mimics with long-linkers bound to TrkA or TrkC receptor and showed partial antagonism for the receptors. Other mimics were conjugated with cytotoxic compounds and they were used for TrkC targeted drug delivery. The last group of bivalent mimics previously showed targeted delivery effects for pancreatic cancer cells. In this study, we synthesized Eu-chelated bivalent mimics to perform a competitive binding assay for pancreatic cancer cells. Previous research in our group focused on design of secondary structures' mimics on rigid scaffolds as "minimalist mimics." We sought to establish structural design criteria for the minimalist mimics, and we wanted to propose that sets of such compounds could mimic local pairs of amino acids in any secondary structures as "universal peptidomimetics." Thus, we designed five compounds, such as oxazoline-, pyrrole-, dyine- "kinked" and "linear" bistrizole-based peptidomimetics, and performed molecular modelings, DFT calculations, and QMD for them to validate our hypothesis. On the concepts of "minimalist mimics" and "universal peptidomimetics," we developed the C alpha ? C beta vector matching program to evaluate preferred orientations of C alpha - C beta coordinates for secondary structures. We applied the program to omegatides and pyrrolinone-pyrrolidine oligomers. The compounds matched better with strands than for helices. We expanded the C alpha ? C beta vector matching idea to a method that ranks preferred conformations of small molecules on any combination of three interface side-chains in all structurally characterized PPIs. We developed a PDB mining program (explores key orientation, EKO) to do this, and EKO applied to pyrrolinone-pyrrolidine oligomers to find targets. EKO found several interesting targets, such as AICAR Tfase, GAPDH, and HIV-1 protease. HIV-1 dimerization inhibition and Zhang-Poorman kinetic assays were performed to validate our hypothesis, and the results showed that pyrrolinone-pyrrolidine derivatives inhibited HIV-1 dimerization.

No description available.

La thérapie photodynamique (PDT) est un type de traitement du cancer qui offre de nombreux avantages. Une stratégie pour améliorer l'efficacité de la PDT est l'élaboration de photosensibilisateurs (PSs) de troisième génération, composés d’une molécule photoactivable couplée à un agent de ciblage. Les travaux de recherche de cette thèse portent sur l'amélioration de la sélectivité du traitement PDT en concevant des PSs ciblés. La première partie de la thèse est consacrée à l'étude d'un PS couplé à de l’acide folique (PS-FA). L’acide folique est une unité bien connue de ciblage qui se lie de façon efficace au récepteur de l'acide folique sur-exprimé à la surface de nombreuses cellules cancéreuses. Nous avons particulièrement vérifié la stabilité de l'acide folique sous l'influence des facteurs environnementaux. La deuxième partie est consacrée à l'étude du peptide KDKPPR conçu pour cibler neuropiline-1, un récepteur surexprimé dans les néovaisseaux. Plusieurs modifications du peptide ont été faites et les analogues ont été testés par des analyses ELISA afin d'évaluer leur capacité de liaison à la suite des modifications. La troisième partie de la thèse a consisté en la synthèse de porphyrines couplées à des blocs porteurs de 1, 2 ou 3 peptides grâce à la technique de chimie click pour former de multiples conjugués avec des nombres différents de porphyrines et peptides attachés aux plateformes / Photodynamic therapy (PDT) is a type of cancer therapy that could offer many advantages. One possible way to improve the effectiveness of PDT is the elaboration of third generation photosensitizers (PSs) which consisted of PSs coupled with targeting agents. This thesis focuses on improving the selectivity of PS delivery through designing targeted PS agents. The first part of the thesis deals with the study of a PS-folic acid (PS-FA). FA is a well-known targeting unit which bonds with high efficiency to folic acid receptor over-expressed on the surface of many cancer cells. We particularly checked the stability of folic acid under the influence of environmental factors. The second part is devoted to the study of KDKPPR peptide designed to target neuropilin-1, a receptor over-expressed in neovessels. Several modifications of the peptide were made and the analogues were tested through ELISA assays to evaluate their binding capability following the modifications. The third part of the thesis is related to the synthesis of porphyrin and peptide building blocks through click chemistry technique to form multiple conjugates with different numbers of porphyrins and peptides attached to the platforms

Ce travail rapporte la synthèse et l'évaluation biologique des molécules hybrides de type isocombrétastatine A-4/belinostat. L'évaluation biologique de cette nouvelle série nous a permis d'identifier deux molécules inhibitrices de la polymérisation de la tubuline ainsi que de la HDAC8 possédant une puissante activité anti-proliférative dans la gamme du nanomolaire. De plus, nous démontrons que le système de catalyseur PtO2/PTSA-MeOH/H2O est très efficace pour convertir les alcynes internes et terminaux en cétones et qu’il est compatible avec une grande variété de groupes fonctionnels. / In this work, we report the synthesis and biological evaluation of isocombretastatin A-4/belinostat hybrid molecules. The biological evaluation of these new series has identified two molecules with potent anti-proliferative activity in the nanomolar range, which exhibit inhibitory activity on tubulin assembly and HDAC8. Second, we demonstrate that the PtO2/PTSA-MeOH/H2O catalyst system is very efficient in converting internal and terminal alkynes to ketones and that it is compatible with a wide variety of functional groups.

Despite the central role of IFNγ in vitiligo pathogenesis, systemic IFNγ neutralization is an impractical treatment option due to strong immunosuppression. However, most vitiligo patients present with less than 20% affected body surface area, which provides an opportunity for localized treatments that avoid systemic side effects. After identifying keratinocytes as key cells that amplify IFNγ signaling during vitiligo, I hypothesized that tethering an IFNγ neutralizing antibody to keratinocytes would limit anti-IFNγ effects to the treated skin for the localized treatment. To that end, I developed a bispecific antibody (BsAb) capable of blocking IFNγ signaling while binding to desmoglein expressed by keratinocytes. I characterized the effect of the BsAb in vitro, ex vivo, and in a mouse model of vitiligo. SPECT/CT biodistribution and serum assays after local footpad injection revealed that the BsAb had improved skin retention, faster elimination from the blood, and less systemic IFNγ inhibition than the non-tethered version. Furthermore, the BsAb conferred localized protection almost exclusively to the treated footpad during vitiligo that was not possible by local injection of the non-tethered anti-IFNγ antibody. Thus, keratinocyte-tethering proved effective while significantly diminishing off-tissue effects of IFNγ blockade, offering a new treatment strategy for localized skin diseases, including vitiligo.

No description available.

No description available.

Anticancer active metal complexes such as cisplatin are routinely used for treating various cancers since 1978. However, the side effects of cisplatin overwhelm its therapeutic potential, especially in the latter stages of treatment. The nonspecific cytotoxicity of drugs could be avoided if targeted delivery to cancer cells is achieved using two different methodologies namely, enhanced permeability and retention in solid tumors (EPR) and receptor mediated endocytosis using a homing agent (RME). Ru(II)-arene complexes which are delivered specifically into cancer cells by the transferrin enzyme are less toxic compared to other metal complexes. The thesis describes the synthesis and use of Ru(II)-η6cymene complexes with different ancillary ligands which modulates the anticancer activity and the utility of two macromolecular vehicles in directed drug delivery. Ru(II)-η6cymene complexes with different heterocyclic ancillary ligands are synthesized and their anticancer activity tested against various cancer cell lines. Ruthenium complexes with mercaptobenzothiazoles are found to be quite active against the H460 cell lines that overexpress transferrin receptors and non-cytotoxic to the normal cell line, HEL299. Biophysical studies show that complexes (H1 and H8) can unwind the pBR322 DNA and inhibit the Topo IIα enzyme. A unique biphasic melting curve of CT DNA is observed in the presence of H1 which is attributed to formation of a dinuclear species (H20). Half-sandwich complexes of 6-thioguanine (6-TG) have also been prepared to improve the delivery and efficacy of 6-TG which is used in spite of a deleterious photoreaction. The Ru complexes cytotoxic to several leukemia cell lines. As they are photostable and anticancer active, they are better than 6-TG. Anticancer activity exhibiting piazselenols are used as ancillary ligands to make Ru(II)-arene complexes. Unfortunately, 1H NMR spectra suggests that piazselenol complexes dissociate in solution. However, the nitro substituted piazselenol and its Ru complex show the greatest cytotoxicity (<0.1 µM) against the A2780 cell line. The utility of PAMAM dendrimers and hyper branched polymers (hybramers) conjugated with a homing agent to target cancer cells by EPR and RME is probed. A cytotoxic copper complex (CuATSM) is covalently attached to the macromolecules through a disulfide linker, cleaved in the presence of GSH. Targeting efficacy of the folic acid-dendrimer conjugates is checked against two glioma cell lines. The folic acid-dendrimer conjugate is more active compared to dendrimer conjugate without folic acid against folate-receptor-overexpressing LN18 cell line. Biotin conjugated dendrimer shows better accumulation in HeLa cells, which require high amounts of biotin for growth. In vivo studies demonstrate that the conjugate can cross the blood-brain barrier. These studies suggest that PAMAM dendrimer can be used as a targeted delivery vehicle for cytotoxic metal complexes. Hyperbranched polymers decorated with propargyl groups and hydrophilic OH terminated TEG groups are attached to biotin and a cytotoxic Cu complex. (CuATSM-SS-CONH-N3) through ‘click’ reactions and tested against the HeLa cell line. On the basis of the studies conducted, it is concluded that targeted delivery of cytotoxic metal complexes are possible in the case of Ru(II) half-sandwich complexes and macromolecular vehicles like dendrimers are suitable for specifically delivering copper complexes into cancer cells.

O objetivo geral deste trabalho foi explorar a versatilidade de filmes multicamadas de polieletrólitos (PEM) e suas aplicações em sistemas de entrega de drogas e como filmes funcionais para aplicações biomédicas. Filmes PEM montados pela técnica de camada por camada (layer­-by­-layer, LbL), foram explorados em três aplicações principais. Na primeira, foi explorado o desenvolvimento de um protocolo de funcionalização em filmes de poli(alilamina)/poli (estireno sulfonato), PAH/SPS. Os parâmetros de construção do filme para biotinilação dos grupamentos amina do PAH foram otimizados e aplicados na captura e detecção do antígeno específico da próstata (PSA), na concentração de 100 a 0,1 ng/mL, usando pontos quânticos (Qdots). Em comparação com outros trabalhos, este sistema apresentou uma boa sensibilidade na detecção de PSA, dentro do limite de detecção clínica de 0,4 a 0,1 ng/mL. A segunda aplicação envolveu o desenvolvimento de filmes de sacrifício baseados nas interações naturais da mucina submandibular bovina e da lectina, jacalina (BSM/JAC). Filmes de BSM/JAC apresentaram estabilidade quando submetidos a uma ampla faixa de pH (pH 3-­-9) e em solução de alta força iônica (5 M NaCl). A dissolução dos filmes BSM/JAC pôde ser seletivamente desencadeada mediante à incubação em solução de melibiose, 37 °C, pH 7,4, sem apresentar citotoxicidade às células. Na última parte deste trabalho, a incorporação de lipossomos ecogênicos (ELIP) em mochilas celulares foi investigada. Mochilas celulares são \"patches\" de 7­-10 &#181;m de diâmetro que podem ser fabricados por meio de deposição alternada de polímeros utilizando-­-se a técnica de LbL, sobre uma matriz pré­-moldada obtida por fotolitografia, a fim de criar um sistema composto por três multicamadas estratificadas: uma região de liberação, para promover o destacamento do substrato, uma região de carga de droga, e uma região adesiva às células. O uso de ELIP permitiu incorporação de até 9x mais doxorrubicina (DOX) se comparado com o fármaco livre em solução absorvido pelos dos filmes. A liberação de DOX pelos filmes foi monitorado por 25 dias. Mochilas contendo ELIP-­DOX foram então aderidos a monócitos, e sua viabilidade monitorados por 72h. Mochilas vazias mostraram diminuir a proliferação de monócitos ao longo das 72 horas, enquanto mochilas carregadas com ELIP-­DOX mostraram uma diminuição dramática na população celular, apontando uma potencialização dos efeitos da droga pela sua proximidade com as células. / The overall goal of this thesis was to exploit the versatility of polyelectrolite multilayers (PEM) to be applied in drug delivery systems and biofunctionalizable films for biomedical applications. PEM films assembled by the layer-by­-layer technique were explored in three main applications. In the first part of this work, the development of a functionalization protocol of poly(allylamine)/poly(styrene sulfonate), PAH/SPS was explored. The optimal film parameters to the use of biotinylated multilayers were applied for the capture and detection of prostate specific antigen (PSA) protein in the range of 100 to 0.1 ng/mL, by using quantum dots. Compared to previous work, this system presented a good sensitivity for PSA detection that is within the clinical limit range of 0.4 to 0.1 ng/mL. The second application involved the creation of a novel sacrificial multilayer film. Films based in natural interactions of bovine submaxillary mucin and the lectin jacalin, BSM/JAC were assembled. BSM/JAC films showed stability when underwent a wide rage of pH (pH 3 to 9) and high ionic strength (5 M NaCl) solutions. BSM/JAC dissolution could be triggered released by incubation in melibiose at 37 °C in pH 7.4 buffer, without cytotoxicity. In the last part of this work the incorporation of echogenic liposomes (ELIP) into cell backpacks was investigated. Cell backpacks are 7-10 &#181;m diameter patches that can be fabricated through LbL polymer deposition onto a photopatterned array to create a stacked composite of three stratified multilayer systems: a releasable region for easy detachment from the substrate, a drug payload region, and a cell adhesive region. The use of ELIP allowed up to 9x more doxorubicin (DOX) loading when compared to free drug in solution adsorbed through the films. DOX release from films was monitored for over 25 days. ELIP­-DOX backpacks were then attached to mouse monocytes and their viability monitored by 72h. Empty backpacks showed to decrease monocytes proliferation over the course of 72h, while ELIP­-DOX backpacks showed a dramatic decrease in cell population, showing that DOX effects were enhancement in drug potency by its proximity.