The role of anionic polysaccharides in the preparation of nanomedicines with anticancer applications.

Cancer has become one of the main causes of death in developed countries, and it is expected to be declared as the disease with the highest worldwide morbidity and mortality indexes in the coming decades. Nanomedicine aims to overcome some problems related to this prevalent disease, particularly the lack of efficient diagnostic and therapeutic tools. The most recent scientific advances, which have conducted to a more personalized medicine, were focused on the production of nanocarriers involved into the transport and the delivery of drugs to targeted cells. A wide variety of nanocarriers composed by different materials have been designed for their use as drug delivery systems. Polysaccharides have emerged as very useful biopolymers among all raw materials used in the preparation of these nanoplatforms. They are highly stable, non-toxic and biodegradable molecules, and also present some chemical properties which are very difficult to reproduce using artificial polymers. Anionic polymers, such as hyaluronic acid, heparin or alginate, present some structural and chemical characteristics which make them ideal polymers to prepare nanosystems with anticancer applications. This review will focus on the description of some anionic polysaccharides and the possibilities they offer towards the preparation of nanosystems with applications in cancer treatment and diagnostics.pre-print889 K

In Vitro Studies of Heparin-Coated Magnetic Nanoparticles for Potential Use in the Treatment of Neointimal Hyperplasia

With the ever-increasing prevalence of atherosclerosis, procedures such as angioplasty and stenting have become common practice, both of which are simple techniques spouting relatively satisfying results for the past several decades. While successful in opening of occluded vessels, these therapies can be met down the line with thrombosis or even repeated occlusion of the vessel, known as restenosis. Similar to the issues faced within oncology, treatment of this restenosis via widespread drug administration throughout the body is not desirable. Cardiovascular and other medical fields have begun looking into the use of magnetic nanoparticles as a drug delivery vessel. Previously, our lab proposed the use of these particles to concentrate and carry drug doses for local delivery as treatment of neointimal hyperplasia leading to restenosis. This pairing would allow concentrated drug doses to be carried directly to the affected vessel position, without adverse effects elsewhere in the vessel or even the entire body

The design of polymeric microneedles for the delivery of sensors for real-time physiological monitoring

Ce mémoire de maîtrise porte sur le développement d’un système d’administration de microaiguilles pour livrer des sondes et des capteurs fluorescents dans le contexte du diagnostic et de la surveillance des soins de santé. Bien que parfois négligés en faveur des soins de santé axés sur le traitement, le diagnostic précoce de la maladie et la surveillance préventive des paramètres biologiques peuvent considérablement améliorer les résultats des soins de santé et joueront probablement un rôle plus important dans les années à venir. Cependant, il reste des obstacles importants à cette approche, à savoir le caractère relativement invasif et perturbateur des analyses biologiques. La nécessité de se rendre dans une clinique et de subir un prélèvement de sang (ou de liquide biologique) invasif présente des inconvénients importants par rapport aux traitements classiques, qui consistent souvent de médicaments pouvant être pris à domicile sans douleur. Une solution à ces problèmes réside dans la mise au point de systèmes minimalement invasifs de diagnostic et de suivi médical, idéalement ceux qui peuvent être utilisés à domicile sans nécessiter de personnel qualifié. À cet égard, les microaiguilles sont une technologie au potentiel énorme, car leur petite taille les rend peu invasives et pratiquement indolores, et leur nature simple à usage unique permet potentiellement une administration à domicile par le patient. Particulièrement prometteuses pour les applications de diagnostic et de surveillance sont les microaiguilles en polymère soluble; fabriquées à partir de polymères synthétiques ou biologiques injectables, ces microaiguilles sont solubilisées après la perforation de la peau, libérant ainsi les composés qu’elles contiennent. Bien que prévu initialement pour la livraison d'agents thérapeutiques, en utilisant ces microaiguilles pour livrer des molécules fluorescentes spécifiquement conçues, il est possible de créer un tatouage médical de diagnostic affichant un signal fluorescent précis. En associant cette technologie à un détecteur de fluorescence portable, la surveillance en temps réel d’un large éventail de paramètres biologiques pourrait devenir accessible en dehors du contexte clinique. Afin de fournir un contexte pour le développement de cette technologie, cette mémoire commence par une revue des principes et des avancées majeures récentes dans le domaine des applications diagnostiques des microaiguilles (Chapitre 1). Par la suite, un tatouage par microaiguille est présenté sous la forme d'un capteur de ROS délivré sur la peau, avec des implications diagnostiques pour le vieillissement et la carcinogenèse de la peau liés aux UV, ainsi que pour des affections inflammatoires telles que le psoriasis, comme validation de concept (Chapitre 2). En outre, un autre tatouage par microaiguille est introduit, consistant d’un capteur spécialement adapté ciblant le système lymphatique, permettant la quantification en temps réel du drainage lymphatique, avec des implications pour la détection précoce de plusieurs affections, notamment le lymphœdème (Chapitre 3).This Master’s thesis concerns the development of a microneedle (MN) delivery system for fluorescent dyes and sensors in the context of diagnostics and healthcare monitoring. While sometimes overlooked in favor of treatment-focused healthcare, early disease diagnosis and preventative monitoring of biological parameters can meaningfully improve healthcare outcomes and will likely play a greater role in coming years. However, significant obstacles to this approach remain, namely the relatively invasive and disruptive nature of biological analyses. The need to travel to a clinic and undergo invasive blood (or biological fluid) sampling presents significant inconveniences relative to common treatments, often consisting of medications that can be taken painlessly at home. A solution to these problems lies in the development of minimally invasive systems for diagnostics and healthcare monitoring, ideally ones which can be used at home without the need for trained personnel. In this regard, MNs are a technology with tremendous potential, as their small size renders them minimally invasive and virtually painless, and their simple, single-use nature potentially allows for at-home administration by the patient. Showing particular promise for diagnostic and monitoring applications are dissolving polymeric MNs; made from injectable synthetic or biological polymers, these MNs are solubilized after breaching the skin, releasing any compound contained within. Though initially envisioned for the delivery of therapeutic agents, by using these MNs to deliver specifically designed fluorescent molecules, it is possible to create a diagnostic medical tattoo displaying a precise fluorescent signal. By pairing this technology with a portable fluorescence detector, real-time monitoring of a wide range of biological parameters could become accessible outside of a clinical setting. To provide context for the development of this technology, this thesis begins with a review of the principles and major recent advances in the field of diagnostic applications of MNs (Chapter 1). Subsequently, a proof-of-concept MN tattoo is introduced in the form of a ROS-sensor delivered to the skin, with diagnostic implications for UV-related skin aging and carcinogenesis, as well as inflammatory conditions such as psoriasis (Chapter 2). Further, another MN tattoo is introduced, consisting of a specifically tailored sensor targeting the lymphatic system, allowing the real-time quantification of lymphatic drainage, with implications in the early detection of several conditions, including lymphedema (Chapter 3)

Magnetic Nanoparticles in the Prevention of Neointimal Hyperplasia

The use of vascular stents to treat occluded blood vessels is common practice; however, this procedure is often complicated by neointimal hyperplasia reocclusion and thrombogenesis. One treatment option is systematically administering heparin to activate antithrombin III leading to deactivation of thrombin and other proteases involved in blood clotting. This treatment is associated with high rates of bleeding and other vascular complications. In addition to the widely known anti-coagulation effects, heparin has long been known to exhibit an anti-proliferative effect on the growth of cells. The ideal solution would be localized delivery to the site of the interest. Recently, the advancements in magnetic resonance have allowed magnetic nanoparticles to be localized at sites of interest. We propose that a heparin-coated magnetite nanoparticle will fit this ideal solution given it\u27s potential to deliver localized anti-coagulation and anti- proliferative effects. In this study, we present the synthesis, characterization, and initial cytotoxicity studies of such a particle. Magnetite nanoparticles were synthesized and characterized to determine magnetic core diameter, hydrodynamic diameter, zeta potential, and heparin loading. Live/Dead and MTS assays were utilized to assess cellular toxicity on vascular smooth muscle cells (VSMCs). Cellular uptake and actin distribution of VSMCs post nanoparticle treatment was observed with Prussian Blue Staining and immunofluorescence respectively. Nanoparticles were characterized by TEM to be in the middle of our target range with a diameter of 24.3nm. Heparin loading was found to range from 0.976 to 2.8896 ug heparin/ug nanoparticle depending on the synthesis batch. Proliferation and cytotoxicity studies on vascular smooth muscle cells showed that at the low loading of heparin on nanoparticles, there is indication of proliferation inhibition without VSMC cell death. There was not a noticeable cellular uptake of heparin nanoparticles; however, actin distribution gives possible indication that VSMCs were induced into their contractile phenotype. The results from this study demonstrate a successful synthesis route of heparin-coated nanoparticles and indications for further investigation of VSMC response

pH responsive gels that deliver anti-inflammatory drugs

Anti-inflammatory drugs can suppress or prevent chronic inflammation. However, uncontrolled application of anti-inflammatory drugs often impair the wound healing process. This can be overcome by combining hydrogel wound dressings with drug delivery systems to achieve stage-dependent drug release. The pH of cutaneous wounds is dynamic and correlates with the stage of the wound healing process, with inflammation being acidic, granulation being progressively alkali, and remodeling returning skin to its pre-injury pH. By taking the advantage of this pH difference, stage-specific wound treatments can be developed to respond to these environmental cues using a pH sensitive hydrogel. In the first part of this study, pH sensitive methacrylated chitosan (MAC) hydrogels were synthesized and characterized through 1H NMR. Chitosan was first methacrylated and then crosslinked through three polymerization methods: step growth by thiol-ene photoclick reaction, chain growth by UV polymerization, and mixed model in which both step growth and chain growth mechanism were used. The resulting hydrogels exhibited adjustable mechanical properties, swelling ratios, and pH sensitivities without affecting degradation behavior and in vitro cell response. Cytocompatibility studies were performed using NIH/3T3 fibroblasts. Cell proliferation was suppressed when seeding on the hydrogel surfaces comparing to tissue culture plastic (TCP), yet no measurable cell death was observed. With appropriate drug delivery systems, the responsivity of these gels to different pH environments may prove useful as stage-responsive wound dressings. However, the therapeutic effects of many modern drugs are limited owing to their low solubility and low half-life in circulation. Furthermore, there is a lack of design principles which adds the difficulty in synthesize efficacious drug carriers. The purpose of the second part of this study is to examine the relationship between drug delivery to cells and the chemical properties of the polymer micelle drug carriers. Polyethylene glycol (PEG) based alternating copolymer poly[(polyoxyethylene)-oxy-5-hydroxyisophthalic] (Ppeg) with PEG molecular weights of 600 and 1000 were synthesized and modified with different alkanes to study the effects of altering the hydrophobic and hydrophilic chain lengths. NMR, critical micelle concentration (CMC), micelle size, and micelle zeta potential of the synthesized polymers were measured. The resulting polymer particles were able to form micelles in aqueous solution with CMCs lower than 0.04 wt%. Drug delivery studies were performed with a model hydrophobic drug, pyrene. Drug loading data showed the polymer particles were able to encapsulate pyrene and has a loading capacity up to 8 wt%. The sustain release ability was measured and the pyrene release was extended over 5 days. Both loading capacity and sustain release ability were found to be highly dependent on CMC. The micelles were exposed to RAW 264.7 cells to determine their cytocompatibility, Most Ppeg polymer micelles showed more than 85% cell viability with and without pyrene loading. Cell internalization of the micelles encapsulated drug was measured both quantitatively and qualitatively and was enhanced compared to unencapsulated drug. Predictive equations of drug loading, releasing, and internalization were obtained by factorial analysis as a function of PEG and alkane chain length. The results indicated that the internalization enhancement of polymer micelle was mainly affected by hydrophilic chain length; neither hydrophobic chain length nor loading capacity has significant influence on internalization

Development of giant liposomal formulation for drug delivery and tissue engineering application

This thesis delineates the development of giant liposomal formulation and application of drug loaded giant liposome encapsulated hydrogel as a theranostics formulation. Liposomes of varying composition of cholesterol and soy lecithin were prepared by ether infusion-homogenization method. Optimization of the composition was done on the basis of number of liposome formed at different lipid compostion and stirrer speed. Physico-chemical characterization of the giant liposome was done by morphology (microscopy) study, vesicle size distribution profile, stability studies at different pH and temperature, efficiency of drug loading, in vitro toxicity of the drug loaded liposomes and hemocompatibility.Loading of giant liposomes inside the hydrogel was done using the sodium alginate and calcium carbonate solution and 0.1 NHCl. Entrapment of giant liposome inside the hydrogel was confirmed by using fluorescence microscope. Then analysis of the mechanical properties was performed using a P3 probe at a test speed of 1mm/sec.In conclusion, giant liposome loaded hydrogel may be used as advanced pharmaceutical formulation for theranostic application

LbL Nano-Assemblies: A Versatile Tool for Biomedical and Healthcare Applications

Polyelectrolytes (PEs) have been the aim of many research studies over the past years. PE films are prepared by the simple and versatile layer-by-layer (LbL) approach using alternating assemblies of polymer pairs involving a polyanion and a polycation. The adsorption of the alternating PE multiple layers is driven by different forces (i.e., electrostatic interactions, H-bonding, charge transfer interactions, hydrophobic forces, etc.), which enable an accurate control over the physical properties of the film (i.e., thickness at the nanoscale and morphology). These PE nano-assemblies have a wide range of biomedical and healthcare applications, including drug delivery, protein delivery, tissue engineering, wound healing, and so forth. This review provides a concise overview of the most outstanding research on the design and fabrication of PE nanofilms. Their nanostructures, molecular interactions with biomolecules, and applications in the biomedical field are briefly discussed. Finally, the perspectives of further research directions in the development of LbL nano-assemblies for healthcare and medical applications are highlighted

Magnetic Nanoparticle Systems for Nanomedicine—A Materials Science Perspective

Iron oxide nanoparticles are the basic components of the most promising magneto-responsive systems for nanomedicine, ranging from drug delivery and imaging to hyperthermia cancer treatment, as well as to rapid point-of-care diagnostic systems with magnetic nanoparticles. Advanced synthesis procedures of single- and multi-core iron-oxide nanoparticles with high magnetic moment and well-defined size and shape, being designed to simultaneously fulfill multiple biomedical functionalities, have been thoroughly evaluated. The review summarizes recent results in manufacturing novel magnetic nanoparticle systems, as well as the use of proper characterization methods that are relevant to the magneto-responsive nature, size range, surface chemistry, structuring behavior, and exploitation conditions of magnetic nanosystems. These refer to particle size, size distribution and aggregation characteristics, zeta potential/surface charge, surface coating, functionalization and catalytic activity, morphology (shape, surface area, surface topology, crystallinity), solubility and stability (e.g., solubility in biological fluids, stability on storage), as well as to DC and AC magnetic properties, particle agglomerates formation, and flow behavior under applied magnetic field (magnetorheology)