Implantable Microsystem Technologies For Nanoliter-Resolution Inner Ear Drug Delivery

Advances in protective and restorative biotherapies have created new opportunities to use site-directed, programmable drug delivery systems to treat auditory and vestibular disorders. Successful therapy development that leverages the transgenic, knock-in, and knock-out variants of mouse models of human disease requires advanced microsystems specifically designed to function with nanoliter precision and with system volumes suitable for implantation. The present work demonstrates a novel biocompatible, implantable, and scalable microsystem consisted of a thermal phase-change peristaltic micropump with wireless control and a refillable reservoir. The micropump is fabricated around a catheter microtubing (250 μm OD, 125 μm ID) that provided a biocompatible leak-free flow path while avoiding complicated microfluidic interconnects. Direct-write micro-scale printing technology was used to build the mechanical components of the pump around the microtubing directly on the back of a printed circuit board assembly. In vitro characterization results indicated nanoliter resolution control over the desired flow rates of 10–100 nL/min by changing the actuation frequency, with negligible deviations in presence of up to 10× greater than physiological backpressures and ±3°C ambient temperature variation. A biocompatibility study was performed to evaluate material suitability for chronic subcutaneous implantation and clinical translational development. A stand-alone, refillable, in-plane, scalable, and fully implantable microreservoir platform was designed and fabricated to be integrated with the micropump. The microreservoir consists two main components: a cavity for storing the drug and a septum for refilling. The cavity membrane is fabricated with thin Parylene-C layers, using a polyethylene glycol (PEG) sacrificial layer. The septum thickness is minimized by pre-compression down to 1 mm. The results of in vitro characterization indicated negligible restoring force for the optimized cavity membrane and thousands of punctures through the septum without leakage. The micropump and microreservoir were integrated into microsystems which were implanted in mice. The microtubing was implanted into the round window membrane niche for infusion of a known ototoxic compound (sodium salicylate) at 50 nL/min for 20 min. Real-time shifts in distortion product otoacoustic emission thresholds and amplitudes were measured during the infusion. The results match with syringe pump gold standard. For the first time a miniature and yet scalable microsystem for inner ear drug delivery was developed, enabling drug discovery opportunities and translation to human

Navigation multi-bifurcations de corps ferromagnétiques avec un scanner d’imagerie par résonance magnétique

RÉSUMÉ Le nombre de personnes atteintes par le carcinome hépatocellulaire (CHC), un type de cancer du foie, est en progression croissante. Mondialement, le CHC est la seconde cause de mortalité chez les patients atteints par le cancer, à cause du taux de survie extrêmement faible. Le pronostic du CHC est très mauvais : aux USA et au Canada, le taux de survie à cinq ans est de 12% et 20% respectivement. Pour les personnes à un stade très avancé, les traitements possibles sont très limités. Un des traitements possibles est la chimioembolisation hépatique qui consiste à injecter des microparticules médicamenteuses dans le foie. L’objectif de ces particules est double : d’une part, elles embolisent les vaisseaux sanguins qui nourrissent les cellules tumorales et, d’autre part, libèrent des médicaments anti-cancer qui vont détruire les cellules malades. Malheureusement, en l’absence de tout contrôle, ces vecteurs thérapeutiques détruisent aussi des cellules saines de l’organe, en général en nombre limité. Pour ainsi améliorer les soins de ces patients, nous proposons d’utiliser le scanner d’imagerie à résonance magnétique (IRM) pour diriger ces microparticules dans la circulation sanguine dans le but de cibler uniquement les cellules malades. Les retombées de ce projet sont multiples pour le patient : entre-autres, diminution des effets secondaires, et procédures moins invasives et plus efficaces. Pas uniquement limitée au foie, la navigation par résonance magnétique (NRM) a réellement le potentiel de révolutionner certaines pratiques médicales et d’améliorer grandement la prise en charge et les soins pour les patients touchés par le cancer. Cette thèse décrit les stratégies à mettre en place afin de réaliser la NRM sur plusieurs canaux consécutifs afin de rendre les procédures de navigation plus ciblées et plus localisées. Pour atteindre cet objectif, plusieurs expériences ont été menées. Tout d’abord, nous avons prouvé qu’il était possible de guider une bille de 1 mm sur 4 canaux consécutifs à l’aide d’une bobine imagerie. Nous avons donc conçu un prototype microfluidique (fantôme) sous la forme d’un arbre, où chaque canal père se divise en deux canaux fils. Nous obtenons alors huit chemins possibles avec trois bifurcations (deux choix possibles à chaque jonction). Nous avons ainsi démontré que le guidage d’une bille sur trois bifurcations était possible, avec des gradients magnétiques inférieurs à 40 mT/m et donc équivalents à ceux utilisés par des IRM cliniques. Des vitesses de déplacement de 14 cm/s ont été mesurées. Suite à ces expériences de guidage, nous avons présenté quelques résultats sur la problématique de l’augmentation de la température : en effet, les bobines de gradient, lorsqu'utilisées pour faire de la navigation, chauffent rapidement et nécessitent des temps de refroidissement. Le ratio durée de guidage sur durée de refroidissement peut ainsi être faible sans stratégie de guidage adaptée. Ainsi, nous suggérons d’utiliser le temps de refroidissement de la bobine de propulsion afin de réaliser des séquences d’imagerie pour, par exemple, évaluer la dose injectée et réévaluer les paramètres de guidage. Expérimentalement, les séquences d'imagerie n'ont pas induit d'augmentation de la température et peuvent donc être exécutées sans perte de performance.----------ABSTRACT The number of new cases of Hepatocellular Carcinoma (HCC), one type of liver cancer, is on the rise. HCC is the second leading cause of cancer death worldwide, due to extremely low survival rate. Prognosis is very poor: the overall 5-year relative survival rate is 12% in the USA and 20% in Canada. The number of available treatments for patients diagnosed at distant stages of the disease is low. A possible treatment is the transarterial chemoembolization (TACE). TACE consists in a combined injection of embolic material and chemotherapeutic drugs. The benefit of TACE is two-fold: embolisation of tumor feeding arteries and local release of anti-cancer drugs directly to the tumoral cells. Unfortunately, without any control, these vectors may reach and kill surrounding healthy liver cells. To increase patient care, we propose to use the Magnetic Resonance Imaging scanner (MRI) as an actuator to navigate therapeutic microparticules into the bloodstream toward liver lesions. Potential outcomes for the patient are, among others, a reduction of side effects and a less invasive intervention. Not restricted to liver, Magnetic Resonance Navigation (MRN) shows promises to drastically change some medical procedures and to increase cancer patient care and management. This thesis decribes strategies to achieve MRN along multiple consecutive channels. In this objective, several experiments have been conducted. Firstly, we showed that a 1-mm bead can be navigated along four consecutives microfluidic channels using an imaging coil. A microfluidic phantom has been designed to obtain eight paths with three bifurcations (two possible choices at every junction). Using magnetic gradient amplitudes lower than 40 mT/m, which are equivalent to clinical MR scanners performance, we successfully steered a bead in all the eight paths. The velocity of the bead reached 14 cm/s. Following these experiments, we worked on potential issues regarding heat rise in the coil. Indeed, imaging coils heats up very quickly when used for MRN and therefore require some time to cool. Without any temperature management strategies, the navigation time over cooling time ratio can be low and thus the procedure duration may be longer. We therefore suggested using the cooling deadtime to apply imaging sequences and acquire information about injected dose or to re-assess navigation parameters. Experimentally, since no temperature rise was measured during the imaging sequences, there is no performance loss. From these observations, more characterisation tests were conducted on the imaging coil to find the most critical parameters regarding the heat rate. We measured an average time of two minutes before the coil reaches its critical temperature. In the worst-case scenario, where at least two gradients are applied simultaneously, less than one minute of propulsion at maximum power is available. From these results, a temperature model has been derived to predict heat rise according to the characteristics of the propulsion sequence. These equations will be integrated within a broad MRN model. Lastly, the inherent design of MRI only allows the application of a single force vector upon all magnetic bodies within a volume. It is therefore impossible to steer a continuous stream of particles along multiple consecutive vessels. One requirement for multiple-bifurcation navigation is therefore to create a discrete injection of particles (bolus) such that only one bolus is navigated at a time. Furthermore, a second requirement for multiple-bifurcation navigation is the synchronisation of the release of the bolus from the catheter with the start of the propulsion sequence

Nanoparticle-based optical interfaces for retinal neuromodulation: a review

Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as “bionic eyes.” However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses

The study of renal function and toxicity using zebrafish (Danio rerio) larvae as a vertebrate model

Zebrafish (Danio rerio) is a powerful model in biomedical and pharmaceutical sciences. The zebrafish model was introduced to toxicological sciences in 1960, followed by its use in biomedical sciences to investigate vertebrate gene functions. As a consequence of many research projects in this field, the study of human genetic diseases became instantly feasible. Consequently, zebrafish have been intensively used in developmental biology and associated disciplines. Due to the simple administration of medicines and the high number of offspring, zebrafish larvae became widely more popular in pharmacological studies in the following years. In the past decade, zebrafish larvae were further established as a vertebrate model in the field of pharmacokinetics and nanomedicines. In this PhD thesis, zebrafish larvae were investigated as an earlystage in vivo vertebrate model to study renal function, toxicity, and were applied in drug-targeting projects using nanomedicines. The first part focused on the characterization of the renal function of three-to four-dayold zebrafish larvae. Non-renal elimination processes were additionally described. Moreover, injection techniques, imaging parameters, and post-image processing scripts were established to serve as a toolbox for follow-up projects. The second part analyzed the impact of gentamicin (a nephrotoxin) on the morphology of the pronephros of zebrafish larvae. Imaging methodologies such as fluorescent-based laser scanning microscopy and X-ray-based microtomography were applied. A profound comparison study of specimens acquired with different laboratory X-ray-based microtomography devices and a radiation facility was done to promote the use of X-ray-based microtomography for broader biomedical applications. In the third part, the toxicity of nephrotoxins on mitochondria in renal epithelial cells of proximal tubules was assessed using the zebrafish larva model. Findings were compared with other teleost models such as isolated renal tubules of killifish (Fundulus heteroclitus). In view of the usefulness and high predictability of the zebrafish model, it was applied to study the pharmacokinetics of novel nanoparticles in the fourth part. Various in vivo pharmacokinetic parameters such as drug release, transfection of mRNA/pDNA plasmids, macrophage clearance, and the characterization of novel drug carriers that were manipulated with ultrasound were assessed in multiple collaborative projects. Altogether, the presented zebrafish model showed to be a reliable in vivo vertebrate model to assess renal function, toxicity, and pharmacokinetics of nanoparticles. The application of the presented model will hopefully encourage others to reduce animal experiments in preliminary studies by fostering the use of zebrafish larvae

Drug Delivery Technology Development in Canada

Canada continues to have a rich history of ground-breaking research in drug delivery within academic institutions, pharmaceutical industry and the biotechnology community

Current Insights on Lipid-Based Nanosystems

Lipid-based nanosystems, including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), cationic lipid nanoparticles, nanoemulsions, and liposomes, have been extensively studied to improve drug delivery through different administration routes. The main advantages of these systems are their ability to protect, transport, and control the release of lipophilic and hydrophilic molecules (either small-molecular-weight molecules or macromolecules); the use of generally recognized as safe (GRAS) excipients that minimize the toxicity of the formulations; and the possibility to modulate pharmacokinetics and enable the site-specific delivery of encapsulated payloads. In addition, the versatility of lipid-based nanosystems has further been demonstrated for the delivery of vaccines, the protection of active cosmetic ingredients, and the improvement of moisturizing properties of cosmetic formulations.Lipid-based nanosystems are well established and there are already different commercially approved formulations for various human disorders. This success has paved the way for the diversification of the pipeline of development, to address unmet medical needs for several indications, such as cancer, neurological disorders, and autoimmune, genetic, and infectious diseases.This Special Issue aims to update readers on the latest research on lipid-based nanosystems, both at the preclinical and clinical levels. A series of 15 articles (six reviews and nine studies) is presented, with authors from 12 different countries, showing the globality of the investigations that are being carried out in this area

Current Insights on Lipid-Based Nanosystems

Lipid-based nanosystems, including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), cationic lipid nanoparticles, nanoemulsions, and liposomes, have been extensively studied to improve drug delivery through different administration routes. The main advantages of these systems are their ability to protect, transport, and control the release of lipophilic and hydrophilic molecules (either small-molecular-weight molecules or macromolecules); the use of generally recognized as safe (GRAS) excipients that minimize the toxicity of the formulations; and the possibility to modulate pharmacokinetics and enable the site-specific delivery of encapsulated payloads. In addition, the versatility of lipid-based nanosystems has further been demonstrated for the delivery of vaccines, the protection of active cosmetic ingredients, and the improvement of moisturizing properties of cosmetic formulations.Lipid-based nanosystems are well established and there are already different commercially approved formulations for various human disorders. This success has paved the way for the diversification of the pipeline of development, to address unmet medical needs for several indications, such as cancer, neurological disorders, and autoimmune, genetic, and infectious diseases.This Special Issue aims to update readers on the latest research on lipid-based nanosystems, both at the preclinical and clinical levels. A series of 15 articles (six reviews and nine studies) is presented, with authors from 12 different countries, showing the globality of the investigations that are being carried out in this area

Synthesis of new pyrazolium based tunable aryl alkyl ionic liquids and their use in removal of methylene blue from aqueous solution

In this study, two new pyrazolium based tunable aryl alkyl ionic liquids, 2-ethyl-1-(4-methylphenyl)-3,5- dimethylpyrazolium tetrafluoroborate (3a) and 1-(4-methylphenyl)-2-pentyl-3,5-dimethylpyrazolium tetrafluoroborate (3b), were synthesized via three-step reaction and characterized. The removal of methylene blue (MB) from aqueous solution has been investigated using the synthesized salts as an extractant and methylene chloride as a solvent. The obtained results show that MB was extracted from aqueous solution with high extraction efficiency up to 87 % at room temperature at the natural pH of MB solution. The influence of the alkyl chain length on the properties of the salts and their extraction efficiency of MB was investigated