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Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2019, Tutors: Maria Sarret Pons, Carlos Rodriguez Abreu, Chromonics are an interesting class of lyotropic liquid crystals with several potential medical and technological applications. Their confinement in emulsions provides an opportunity to design advanced organic-based materials. In this work, 9 dyes are tested in order to establish chromonic behaviour. Their phases are characterized using Polarized Optical Microscopy and Small Angle X-Ray Scattering (SAXS). Some of them are used for the formulation of stable water-in-oil (W/O) and water-in-water (W/W) emulsions, which are characterized using rheological techniques. Mesogenic phases were observed in seven of the nine studied dyes. Acid red 27, Alcian blue (chloride and acetate salts), Congo red and Neutral red acetate formed chromonic nematic (Nc phase) and hexagonal (M phase) columnar phases. The structure of their phases was not characterized due to partial insolubility. The representative chromonic phases are shown through the partial phase diagram of nickel (II) phthalocyanine tetra-sulfonic acid. This compound stacks in cylindrical columns in both Nc and M phases, with a diameter of one molecule. Two of the studied dyes were used to formulate the emulsion confinement. Representative optical textures of these systems were observed, as star-like and tactoid forms. The chromonic nematic phase of pinacyanol acetate was confined in drops of W/O emulsions with polydimethylsiloxane, vinyldimethylsiloxy terminated as the oil phase. The drop size was highly polydisperse and above 2 [mi]m. This emulsion showed a Newtonian rheology behaviour. Nickel (II) phthalocyanine tetra-sulfonic acid chromonic nematic phase was confined in W/W emulsions with added polyvinylpirrolydone. The W/W emulsion presented a polydisperse drop size larger than 1 [mi]m and showed a Newtonian behaviour. Other oils, surfactants and polymers were tested.

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2023, Tutors: Josep Puigmartí-Luis, Maria Guix Noguera, Ramón Santiago Herrera Restrepo, Nowadays, ischemic stroke is one of the most common and dangerous medical conditions, occurring when a blood clot blocks an artery in the brain vascular system. As a leading cause of mortality worldwide, there is an ever-increasing drive to improve diagnosis and treatment for hemostatic diseases. Microfluidic devices have proved to be one the best experimental platform to study hemostasis’ mechanism, being able to reproduce the interaction between hemodynamics and thrombus. Therefore, clots with mechanical and biological properties closer to native blood clots can be created and studied inside microfluidic chips. In this work, we aim to develop and optimize a 5-inlet microfluidic device to create blood clots by mimicking the physiological environment during blood coagulation. In particular, our goal is to induce coagulation by co-flowing whole blood with tissue factor, simulating the extrinsic pathway of coagulation cascade. Creating a reaction-diffusion area inside the chip will allow us to modulate the reagents mixing point and the blood clot location, as the mixing event is governed by diffusion rates. Toward that goal, we evaluated the effect of flow rate and viscosity inside our device to finally create two controlled blood clots with different sizes and locations. This approach of providing a fine control over blood clots will serve in the future as an in vitro testing platform for drug screening assays

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2023, Tutors: Jordi Ignés Mullol, Francesc Sagués Mestre, Ramon Santiago Herrera Restrepo, Liquid crystals (LCs) are unique states of matter that exhibit both liquid and crystal properties. From the 19th century until now, extensive research has been carried out to understand and take advantage of the fascinating properties of liquid crystals. An intriguing subclass of liquid crystals is the lyotropic chromonic liquid crystal (LCLC). Unlike thermotropic liquid crystals as 5CB, which form through temperature changes, LCLCs are formed when certain organic molecules, known as chromonic dyes, are dissolved in solvents such as water. These LCLCs exhibit a rich variety of phase behavior and unique optical properties, making them of great interest to various applications, including screens, sensors, and biomedical devices. One of the most famous LCLC is Sunset Yellow (SSY). To Describe the confinement of 5CB and SSY and observe phenomena such as the boundary effects in emulsified droplets will be one of the aims of our work. In order to form the emulsions, microfluidic systems will be used. They use small channels and precise control of fluid flows to create well-defined structures and patterns of liquid crystals. This approach offers several advantages, such as high performance, precise control of the size and shape of droplets, and the ability to create complex geometries. Once the emulsions are generated, we will study the properties of confined LCs in droplets and their behavior in front of an external magnetic field.