Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Centrifugal microfluidic platform for applications in low-concentration biosensing of E. Coli(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-11) Farías Álvarez, Mario Alfredo; Madadelahi, Masoud; emimmayorquin, emipsanchez; Salinas Salazar, Carmen Lizzeth; Pilloni Choreño, Oscar; School of Engineering and Sciences; Campus MonterreyAccess to clean and drinkable water is not yet a possibility in many parts of the world. In different regions or rural areas where common water sources are prone to contamination or places where the water treatment does not follow a strict and efficient protocol for disinfection and purification, different pathogens can end up being consumed by several people. Water in these and other places can be contaminated with relative ease, potentially facing from hundreds to thousands of deaths all around the world from diseases caused by unsafe water treatment and pathogenic bacteria. The bacteria Escherichia Coli O157:H7 is a highly pathogenic bacteria that causes a series of gastrointestinal complications and diseases. If left untreated, the consequences can be fatal. Because of this, the need for early detection of this pathogen in water supplies is of great importance. Aptamers are single-stranded chains of DNA or RNA whose sequence can be designed to fold into specific shapes. They can act as an alternative to antibodies for the recognition and binding to antigens and targets of interest. Aptamers have been studied for this potential, and have been successfully synthesized to bind to components in the outer cell membrane of pathogenic bacteria, allowing for a high selectivity. Dendrimers are poly-branched polymers that have the advantage of being able to grow to various generations, exponentially increasing the number of branches they have. Polyamidoamine dendrimers have been studied and researched for their potential in biomedical applications. The functional groups of the branches can be modified and have attached a functional group with the purpose of integrating them into sensing devices. The multiple branches of polyamidoamine dendrimers can then serve as multiple attachment sites for aptamer placement, increasing the amount of bacteria-capturing agents on a biosensing surface. Flow reciprocation is a concept that has been introduced in microfluidic devices, and consists in driving the fluid either actively or passively through a a microfluidic circuit in two directions. This can allow the fluid sample to return to the source or point of origin in the microfluidic device. This concept can be present in centrifugal microfluidics, in which passive ways of reciprocation have been implemented successfully. Pneumatic chambers have been used in order to achieve flow reciprocation by compressing air during the rotation of the device and expanding it during its deceleration. The compression of air is caused by the fluid entering the pneumatic chamber, and it returns to the source chamber due to the air expansion. Since this technique requires high rotational velocities, an alternative is to use flexible membranes as passive pumps that inflate upon rotation and relax during deceleration. These membranes allow for lower rotational speeds and the potential of ease of reciprocation. Flow reciprocation can then be used in biosensors to increase the interaction between the target and the biosensing surface. Then, this can be applied to increase the capturing of pathogenic bacteria by combining this concept with aptamers and dendrimers to achieve low limits of detection. Trial and error of microfluidic devices designs often leads to unused devices that end up discarded and in the trash, which translates into material going to waste. In order to optimize the design and save fabrication resources, computational simulations can be of use. By modeling the desired microfluidic device, one can change any relevant parameters before the actual fabrication of the final device. Lumped-element models are representations of a microfluidic circuit in which each component is governed by its own set of equations and global, system-wide variables are transmitted through ports, obeying Kirchhoff’s laws. The present work aims to combine all of these concepts into a centrifugal microfluidic device for the detection of Escherichia Coli O157:H7 pathogenic bacteria, utilizing aptamers attached to polyamidoamine dendrimers to have multiple capturing sites and using flow reciprocation to enhance the interaction between the bacteria and the aptamers for increased capturing. Fur- thermore, it aims to further develop a lumped-element model for the simulation of centrifugal microfluidic devices, incorporating a new component with elastic membranes for the purpose of flow reciprocation. A limit of detection of 8.137 × 103 CFU/mL was achieved.
- Application and evaluation of aptamers in the design of the biosensor for the capture of testosterone and/or its synthetic analogs in food supplements.(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024) Medina Benítez, Ariadna; Antonio Pérez, Aurora; emimmayorquin; Aranda Barrandas, Maria Eugenia; School of Engineering and Sciences; Campus Estado de México; Torres Huerta, Ana LauraThe present project arises from the need to develop a detecting tool for the presence of testosterone and its synthetic analogs in food supplements. Testosterone and its synthetic analogs are part of the androgenic-anabolic steroids (AASs) that are also cataloged as prohibited substances for food supplements since they have several adverse effects. The presence of AASs poses a significant public health issue due to several factors. These include the lack of strict regulations, the rise in consumption of food supplements, and the challenges associated with current analytical methods for assessing supplement composition. In response to this growing problem, the project searches to develop a competitive detection tool with high affinity, real-time detection, and user-friendly operation. To achieve this, the development of a biosensor was proposed, focusing on its two main components: (1) the biorecognition element, utilizing aptamers for their ability to specifically recognize and capture small analytes, and (2) the transducer element, employing gold nanoparticles (AuNPs) for their chemical and optical properties, which enable them to attach to aptamers via thiol modification. For this study, eight aptamers (apT5, P4G13, TESS1, TESS2, TESS3, T4, T5.1, and T6) with previous reports of interaction with testosterone were evaluated to select the best candidate regarding the structural stability at different ionic concentrations and temperatures values, as well as best affinity and interaction characteristics with testosterone, androstenedione, and testosterone undecanoate. In silico analysis allows us to know the stability and behavior of each analyzed aptamer and evaluate the aptamer’s ability to interact with its target. On the other hand, an in vitro analysis tracks the changes in the folded and unfolded aptamer dimensions monitored by the Dynamic Light Scattering (DLS) technique and the structural changes using the Circular Dichroism (CD) technique, both under the previously in silico conditions. An intermediate step was to construct and characterize the size of the biosensing platform (aptamer-AuNPs) and the binding complex (aptamer-AuNPs-analyte) using the DLS technique. To analyze the affinity with the analytes we performed relative capture tests with testosterone and testosterone undecanoate. The results from the in silico approach were consistent with the experimental data gathered, exhibiting that the sequence size in bp, and aptamers native conformation, intervene in their affinity and biosensor functionality. The aptamers apT5, P4G13, and T4 were discarded as possible candidates because they did not show stability and optimal affinity in the in silico analysis. T5.1, and T6 proved to be functional aptamers because they showed good affinity but less stability, both in silico and in vitro, TESS2, and TESS3, showed optimal stability and affinity, however, TESS1 turned out to be the best candidates because of their stability and number of interactions, which translates into a greater affinity, compared to the rest.
- ZnO/FTO based biosensor deposited via spin coating method for bacteria detection(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2023-12) Rojas Pablos, Ernesto; López Mena, Edgar René; dnbsrp; Ceballos Sanchez, Oscar; Sanchez Ante, Gildardo; Sanchez Martínez, Araceli; Escuela de Ingeniería y Ciencias; Campus Guadalajara; Navarro López, Diego EloyrTransparent oxide conductors have been an up-and-coming research topic thanks to their excellent conductive and optoelectric properties. This type of materials are the basis for some of the current technological advances in areas such as sensing devices, transistors, and solar cells. A biosensor consists of an analog component that translates the presence of biomolecules or minerals into an electrical signal that can be processed and later interpreted by the user for future work. The adaptation of nanotechnology to biosensors can provide nanoscale analysis for the detection of biomolecules. The deposition of different nanomaterials into biosensors has made possible the creation of highly sensitive and selective biosensors, which are desired properties for sensing devices. This research presents the design of a ZnO/FTO-based amperometric biosensor deposited via spin coating technique for bacteria detection on a molecular scale. The deposition of a ZnO thin film layer provides detection capabilities to the FTO in order to determine the presence of bacteria. As the ZnO thin film layer serves as an active region, the presence of the bacteria induces a change in the current measured through the biosensor when a voltage is applied. The characterization of the ZnO thin film as well as the electrical characterization of the biosensor were performed in order to prove the functionality of the device. Material characterization revealed a successful deposition of ZnO in the FTO glass substrate, obtaining a compact thin film consisting of spherical agglomerations of material. The electrical characterization reveled a change in current to different bacteria samples employed at different concentrations with \textit{Escherichia coli} showcasing the most sensitive results. The obtained biosensors proved to be functional for the detection of the presence of bacteria in very controlled parameters, proving ZnO as an effective alternative for future nano-biosensor devices.
- Numerical modelling of a nanoplasmonic biosensor based on a Mach-Zehnder interferometer(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-06-03) Félix Rendón, Ulises; De León Arizpe, Israel; lagdtorre/tolmquevedo; Martínez Chapa, Sergio Omar; Hernández Aranda, Raúl Ignacio; School of Engineering and Sciences; Campus MonterreyIn the last few decades, optical biosensors based on surface plasmon resonance (SPR) have attracted increasing attention as a label-free alternative for the detection of small traces of biological and chemical markers, for application ranging from drug discovery and medical diagnosis to food quality and national defense. These approaches exploit the high sensitivity of surface plasmons polaritons (SPPs) to variations in the refractive index of the medium surrounding a thin metal film, which is caused by adsorption of the analyte molecules in the metal-dielectric interface. However, nowadays the plasmonic biosensor platforms with best performance require of complex optical configurations and bulky instrumentation, which difficult its miniaturization capability and portability, limiting its integration with other bioanalytical tools. In this work, we propose a novel design based on a Mach-Zehnder interferometer (MZI), consisting on a gold layer with a subwavelength aperture surrounded by grooves, and a detection system based on intensity interrogation. Our proposed architecture contemplates independent control of the reference and sensing arms in a planar disposition, which allows the biosensor to operate in the region of maximum sensitivity for low-analyte concentration and avoid the requirement of using complex multilayer fabrication techniques. Through numerical simulations using the FDTD-method, we found that our platform performed satisfactorily compared to previously reported designs. Moreover, its miniaturization potential, small footprint, and simple illumination scheme make it an ideal candidate for use in integrated sensing systems, which can be further enhanced by multiplexing.