Enzyme Powered Nanomotors Towards Biomedical Applications

[eng] The advancements in nanotechnology enabled the development of new diagnostic tools and drug delivery systems based on nanosystems, which offer unique features such as large surface area to volume ratio, cargo loading capabilities, increased circulation times, as well as versatility and multifunctionality. Despite this, the majority of nanomedicines do not translate into clinics, in part due to the biological barriers present in the body. Synthetic nano- and micromotors could be an alternative tool in nanomedicine, as the continuous propulsion force and potential to modulate the medium may aid tissue penetration and drug diffusion across biological barriers. Enzyme-powered motors are especially interesting for biomedical applications, owing to their biocompatibility and use of bioavailable substrates as fuel for propulsion. This thesis aims at exploring the potential applications of urease-powered nanomotors in nanomedicine. In the first work, we evaluated these motors as drug delivery systems. We found that active urease- powered nanomotors showed active motion in phosphate buffer solutions, and enhanced in vitro drug release profiles in comparison to passive nanoparticles. In addition, we observed that the motors were more efficient in delivering drug to cancer cells and caused higher toxicity levels, due to the combination of boosted drug release and local increase of pH produced by urea breakdown into ammonia and carbon dioxide. One of the major goals in nanomedicine is to achieve localized drug action, thus reducing side-effects. A commonly strategy to attain this is the use moieties to target specific diseases. In our second work, we assessed the ability of urease-powered nanomotors to improve the targeting and penetration of spheroids, using an antibody with therapeutic potential. We showed that the combination of active propulsion with targeting led to a significant increase in spheroid penetration, and that this effect caused a decrease in cell proliferation due to the antibody’s therapeutic action. Considering that high concentrations of nanomedicines are required to achieve therapeutic efficiency; in the third work we investigated the collective behavior of urease-powered nanomotors. Apart from optical microscopy, we evaluated the tracked the swarming behavior of the nanomotors using positron emission tomography, which is a technique widely used in clinics, due to its noninvasiveness and ability to provide quantitative information. We showed that the nanomotors were able to overcome hurdles while swimming in confined geometries. We observed that the nanomotors swarming behavior led to enhanced fluid convection and mixing both in vitro, and in vivo within mice’s bladders. Aiming at conferring protecting abilities to the enzyme-powered nanomotors, in the fourth work, we investigated the use of liposomes as chassis for nanomotors, encapsulating urease within their inner compartment. We demonstrated that the lipidic bilayer provides the enzymatic engines with protection from harsh acidic environments, and that the motility of liposome-based motors can be activated with bile salts. Altogether, these results demonstrate the potential of enzyme-powered nanomotors as nanomedicine tools, with versatile chassis, as well as capability to enhance drug delivery and tumor penetration. Moreover, their collective dynamics in vivo, tracked using medical imaging techniques, represent a step-forward in the journey towards clinical translation.[spa] Recientes avances en nanotecnología han permitido el desarrollo de nuevas herramientas para el diagnóstico de enfermedades y el transporte dirigido de fármacos, ofreciendo propiedades únicas como encapsulación de fármacos, el control sobre la biodistribución de estos, versatilidad y multifuncionalidad. A pesar de estos avances, la mayoría de nanomedicinas no consiguen llegar a aplicaciones médicas reales, lo cual es en parte debido a la presencia de barreras biológicas en el organismo que limitan su transporte hacia los tejidos de interés. En este sentido, el desarrollo de nuevos micro- y nanomotores sintéticos, capaces de autopropulsarse y causar cambios locales en el ambiente, podrían ofrecer una alternativa para la nanomedicina, promoviendo una mayor penetración en tejidos de interés y un mejor transporte de fármacos a través de las barreras biológicas. En concreto, los nanomotores enzimáticos poseen un alto potencial para aplicaciones biomédicas gracias a su biocompatibilidad y a la posibilidad de usar sustancias presentes en el organismo como combustible. Los trabajos presentados en esta tesis exploran el potenical de nanomotores, autopropulsados mediante la enzima ureasa, para aplicaciones biomédicas, y investigan su uso como vehículos para transporte de fármacos, su capacidad para mejorar penetración de tejidos diana, su versatilidad y movimiento colectivo. En conjunto, los resultados presentados en esta tesis doctoral demuestran el potencial del uso de nanomotores autopropulsados mediante enzimas como herramientas biomédicas, ofreciendo versatilidad en su diseño y una alta capacidad para promover el transporte de fármacos y la penetración en tumores. Por último, su movimiento colectivo observado in vivo mediante técnicas de imagen médicas representan un significativo avance en el viaje hacia su aplicación en medicina

Sustainability, innovation and finance: integration challenges

This book aims to provide an introduction to the main characteristics of the innovation and green financing promoting sustainable developments. Both innovative and green activities are phenomena with positive externalities and are, among other things, characterized by underfunding. The state, the regulator, has a significant role in boosting innovation and green ecosystems as well, including funding systems. Besides, green things are often innovative; therefore, they are a subset of innovative, creative companies/activities. The discipline is currently fragmented into the following: innovation macro- and microeconomics; sustainability studies macro and micro (e.g. SCR) level, innovation (corporate) management; innovation finance systems (crowdfunding, venture capital) and green approaches. The text tries to integrate the different approaches and methods, which would give it a novelty

Structural aspects of molecular recognition

This thesis describes the design, implementation and application of a novel docking algorithm. Chapter 1 reviews some important facts about proteins and protein structure. Several molecular recognition systems are examined in detail. This Chapter also reviews a representative set of recent protein/protein docking methods and discusses their relative merits. Chapter 2 sets out the aims of the new docking algorithm, called DAPMatch, and gives full details of its implementation on a parallel architecture computer. The testing of the algorithm is also discussed. Subsequent chapters describe the application of the DAPMatch algorithm to a number of docking problems. DAPMatch is used to reconstruct the known structures of three antibody/lysozyme complexes, using the unbound structure of lysozyme. For the first time a model of the D1.3 antibody is used as a target molecule for a docking algorithm. These results are presented in Chapter 3 and analysed in detail to demonstrate their significance; non-native solutions are also examined. Chapter 4 describes the practical use of the DAPMatch algorithm in a modelling situation, to construct a hypothetical structure for the high molecular weight epidermal growth factor complex. Chapter 5 describes the adaptation of the DAPMatch algorithm to investigate α-helix/α-helix docking, and presents the results obtained. Chapter 6 explains the conclusions that were derived from this work, and suggests possible future enhancements to the algorithm

Computational Modeling and Design of Protein and Polymeric Nano-Assemblies

Advances in nanotechnology have the potential to utilize biological and polymeric systems to address fundamental scientific and societal issues, including molecular electronics and sensors, energy-relevant light harvesting, â??greenâ?? catalysis, and environmental cleanup. In many cases, synthesis and fabrication are well within grasp, but designing such systems requires simultaneous consideration of large numbers of degrees of freedom including structure, sequence, and functional properties. In the case of protein design, even simply considering amino acid identity scales exponentially with the protein length. This work utilizes computational techniques to develop a fundamental, molecularly detailed chemical and physical understanding to investigate and design such nano-assemblies. Throughout, we leverage a probabilistic computational design approach to guide the identification of protein sequences that fold to predetermined structures with targeted function. The statistical methodology is encapsulated in a computational design platform, recently reconstructed with improvements in speed and versatility, to estimate site-specific probabilities of residues through the optimization of an effective sequence free energy. This provides an information-rich perspective on the space of possible sequences which is able to harness the incorporation of new constraints that fit design objectives. The approach is applied to the design and modeling of protein systems incorporating non-biological cofactors, namely (i) an aggregation prone peptide assembly to bind uranyl and (ii) a protein construct to encapsulate a zinc porphyrin derivative with unique photo-physical properties. Additionally, molecular dynamics simulations are used to investigate purely synthetic assemblies of (iii) highly charged semiconducting polymers that wrap and disperse carbon nanotubes. Free energy calculations are used to explore the factors that lead to observed polymer-SWNT super-structures, elucidating well-defined helical structures; for chiral derivatives, the simulations corroborate a preference for helical handedness observed in TEM and AFM data. The techniques detailed herein, demonstrate how advances in computational chemistry allot greater control and specificity in the engineering of novel nano-materials and offer the potential to greatly advance applications of these systems

Particle motion and gradient dynamics in turbulent flows: Theory and Numerical Simulations

L'abstract è presente nell'allegato / the abstract is in the attachmen

Architecture and Community Variability within the Antelope Creek Phase of the Texas Panhandle

This study is concerned with examining the causes underlying cultural variation. The rationale for examining cultural variation is to elucidate the adaptive relationship of the cultural system within its natural and social environmental contexts. Changes in the environment will engender fundamental modifications of the entire cultural system, which in preindustrial semi-sedentary cultures will be manifested by alterations in architectural, community and settlement patterns, along with other tangible aspects of the cultural system. The study focuses on delineating cultural variability of the Antelope Creek phase, a late prehistoric village manifestation on the Southern High Plains of North America. Architectural remains from 28 extensively excavated sites from an 80 kilometer segment of the Canadian River are used to delineate the range of household and community patterns within the settlement system. Artifactual, mortuary, chronometric and physical environmental information are used in conjunction with the architectural data to examine functional, social, temporal and spatial factors potentially contributing to the household and community variability. IV Many community trends not reconciled by these factors are comprehensible when the natural and social context of the larger region is considered. The present environmental conditions are marginal for dependable maize production, and paleoenvironmental reconstructions indicate that xeric conditions were intensifying throughout the duration of the manifestation. The presence of springs issuing fossil water from the Ogallala aquifer during the on-set of drought conditions underlies the development of the Antelope Creek cultural system. Intensification of drought conditions adversely affected the economic base. In an attempt to alleviate the resulting population stress, a series of buffering mechanisms were implemented in a futile attempt to maintain the Plains Village pattern. A break down in social cohesion, shifts in settlement patterns towards lateral tributaries, expansion of trade networks with adjacent groups, and the development of raiding behavior were unsuccessfully employed to retain the Antelope Creek cultural system. Ultimately these measures proved to be inadequate, and by the sixteenth century, other major alterations in settlement and subsistence patterns were required, which radically changed the cultural system. Ultimately these measures proved to be inadequate, and by the sixteenth century, other major alterations in settlement and subsistence patterns were required, which radically changed the cultural system

Of marks and meaning : a palaeographic, semiotic-cognitive, and comparative analysis of the identity marks from Deir el-Medina.

  De dissertatie analyseert de aard en structuur van een oud-Egyptisch merktekensysteem en onderzoekt de relatie van deze niet-linguïstische vorm van visuele communicatie tot het linguïstische systeem van schrift. Ook worden merktekensystemen als universeel fenomeen, waar in onze eigen maatschappij nog volop gebruik van wordt gemaakt, geanalyseerd.  Middle Eastern Studie