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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- Development and characterization of nanoparticle-based composites for fire-retardant cotton fabrics(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-12-03) Briones Baños, Michelle; Sánchez Rodríguez, Elvia Patricia; mtyahinojosa, emipsanchez; Murillo Hernández, José Alberto; Escuela de Ingeniería y Ciencias; Campus Estado de México; Almanza Arjona, Yara CeciliaCotton the most widely used natural textile fiber worldwide, but its high flammability posed a great safety concern, especially in occupational environments where workers remain vulnerable to fire-related injuries. There is a growing need for accessible, low-toxicity and effective flame-retardant solutions that can be applied to cotton. In this context, this study evaluates two environmentally conscious treatment routes: one based on chitosan and another based on citric acid combined with sodium hypophosphite (CA + SHP), and examines the effect of the incorporation of zinc oxide nanoparticles (ZnO NPs) into each system. ZnO NPs were synthesized by a typical reproducible precipitation method, producing high-purity, crystalline nanomaterials, confirmed by FTIR, Raman spectroscopy, and SEM. Both treatment systems were applied to cotton fabric without altering its color or dimensions. Chitosan introduced a slight increase in stiffness, while CA + SHP preserved the original softness. SEM confirmed that both coatings were deposited on the fiber surface but formed distinct morphologies, with chitosan generating films and CA + SHP producing localized deposits. Energy dispersive X-ray spectroscopy (EDS) revealed that ZnO NPs were deposited evenly throughout the fabric, without forming agglomerations. FTIR results indicated that the cellulose structure was unchanged after treatment, and XRD confirmed the predominantly amorphous nature of the chitosan films. Thermal analyses revealed that the treatments modified the decomposition behavior of cotton through different mechanisms. The chitosan–ZnO system shifted the main pyrolysis stage by 30 °C, indicating improved thermal stability, whereas the CA + SHP system reduced moisture sensitivity and generated a more thermally stable char residue. DSC supported these observations by showing reduced degradation peak intensities in all treated samples. The vertical flame test highlighted complementary fire-retardant behaviors. Chitosan-based formulations substantially reduced flame duration but produced weak char and long afterglow, whereas the CA + SHP system did not suppress flaming but strongly inhibited glowing combustion and produced short, cohesive char lengths. These differences demonstrate that the two formulations act at different stages of combustion: chitosan primarily affects flaming behavior, while CA + SHP reduces afterflame times. Overall, this work provides a comparative evaluation of two flame-retardant systems for cotton and identifies their respective strengths and limitations. The results suggest that combining their complementary mechanisms may enable more balanced, accessible, and effective fire-retardant treatments for protective clothing, with potential relevance for industries in regions where burn-related injuries remain a critical concern.
- Fabrication of Chitosan-Alginate Core-Shell Mircogels Incorporated with luminescent Cabron Dots for Biomedical Applications(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024-06) Macias Frotto, Elioth Daniel; Ray, Mallar; emimmayorquin; Verduzco, Lidia Elizabeth; School of Engineering and Sciences; Campus Monterrey; Masoud, MadadelahiBiopolymer microgels present many opportunities in biomedicine and tissue engineering. Among diverse types of microgels, core-shell microgels are of special significance since they may be designed to have a solid core surrounded by liquid-like shell or vice-versa and can be made responsive to external stimuli. Under suitable stimulus (e.g. pH or temperature of a solution containing the microgels) the outer shell may be diluted, thereby releasing the core’s material. Such strategies provide promising possibilities for controlled drug delivery and other biological applications. Additionally, nanoparticles having different functionalities can be embedded in these microgels to enhance or tune their overall properties, thereby making them amenable for variety of applications. In this investigation we develop a novel method to produce chitosan-sodium alginate (CS-SA) core-shell microgels in a single step process using a specially designed high throughput centrifugal microfluidic device (HTCMD). We subsequently incorporated nitrogen functionalized graphene quantum dots (NGQDs) in the core-shell microgels which render them luminescent under UV excitation and are expected to enhance the physical and biological characteristics of the hydrogel microspheres. Initial part of this study was focused on designing and fabricating a microfluidic device that could generate core-shell microgels with controllable geometry and sizes. After several attempts with planar structures we converged on a 3D printed multichannel cylindrical HTCMD that could produce core-shell structures with desired control over size and shape. An analysis of the of microgels generated using the specially designed HTCMD was carried out in order to develop an understanding of the ways in which characteristics of the device such as the diameter of the nozzle and the rotating velocity influence the size, shape, and homogeneity of the generated microparticles. Using a nozzle diameter of 310 µm we could obtain core-shell microspheres having an average diameter of 444 µm at 2500 rpm. On the other hand, a variation of angular velocity between 900 to 2500 rpm allowed us to generate microspheres with average diameters varying between 1500 to 400 µm depending on the nozzle diameter. Following successful fabrication of the HTCMD and controlled generation of spherical core-shell microgels, we investigated the structural, compositional and optical properties of the microgels using a variety of techniques. Fourier transform infrared spectroscopy (FTIR) spectra of the as-prepared core-shell microgels for different concentrations of CS and SA and for the NGQD incorporated microgels revealed that the overall bonding architecture is strongly dependent on the concentrations of CS and SA and is marginally affected by the presence of NGQDs. X-ray diffraction (XRD) of NGQD, CS-SA core-shell microgels and the NGQD incorporated CS-SA particles reveal signatures of crystallinity in all the three samples although sharp crystalline features are not present in any of the samples. In case of NGQD this is attributed to the nanometric size of the crystalline domains while in CS and SA samples the presence of amorphous constituents dominate. Scanning electron microscopy (SEM) alongside brightfield microscopy showed the formation of distinct core-shell interface between CS and SA core-shell structure. UV-vis absorption spectra of all the samples exhibit standard absorption characteristics suggesting the formation of structures with desired electronic transitions. The NGQDs demonstrate excellent room temperature photoluminescence (PL) emission with a PL peak at 444 nm for an excitation of 350 nm. The CS SA core-shell particles exhibit a very weak room temperature PL but following NGQD incorporation their emission is completely defined by the characteristics of the NGQDs. The size and shape controlled, luminescent hydrogel core-shell microspheres have immense potential applications in the fields of drug delivery and tissue engineering. This work proposes a simplified method for the synthesis of microgels by utilizing the pH-dependent sol-gel transition qualities of chitosan, the ionic crosslinking capabilities of alginate. The simplicity of the centrifugal microfluidic platform utilized in the research make it possible to exert exact control over the architecture of the microgel, which in turn promotes a synthesis process that is both easy and extremely effective.
- Fabrication and characterization of microalgae extract loaded chitosan/alginate-based nanoparticles with ultraviolet protection features(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2022-12-06) Santiesteban Romero, Berenice; Iqbal, Hafiz Muhammad Nasir; puemcuervo, emipsanchez; Martínez Ruiz, Manuel; Coronado Apodaca, Karina Guadalupe; Gámez Méndez, Ana María; School of Engineering and Sciences; Campus Monterrey; Sosa Hernández, Juan EduardoMicroalgae are constantly exposed to ultraviolet rays because they are usually found in areas with high sunlight exposure. Several studies have addressed the harmful impact of increased ultraviolet radiation on various microalgae. However, some microalgae have a great ability to overcome or counteract different stresses such as intense solar ultraviolet radiation, this has been happening over the years and with the evolution of microalgae, some examples of defense and/or tolerance mechanisms are DNA repair, synthesis of antioxidants, and enzymatic/non-enzymatic compounds, such as mycosporine-like amino acids and scytonemin to counteract the harmful effects of ultraviolet radiation. This characteristic has not only been investigated to learn more about microalgae, but also for applications such as product creation, since they grow rapidly and are considered the most promising and sustainable sources of biomass. Due to their performance under optimal conditions, they have been widely studied for different bioproducts. Which is why microalgae extracts, by showing resistance to both types of rays, show great potential as sunscreens and this gives a very strong advantage to future bioproducts. This study deals with the application of microalgae extracts for the creation of polymeric nanoparticles based on chitosan and alginate. The synthesis of nanoparticles with a size of 500 nm and a polydispersity index of 0.1 was successfully achieved, indicating the uniformity of these nanoparticles. Different characterization techniques were used for the analysis of these nanoparticles, including UV-Visible spectrophotometry (UV-Vis), Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). All these techniques allow us to see different aspects of the nanoparticles confirming their structure, uniformity, and composition for further effective utilization.
- Optimization of nanocomposite hydrogels for the treatment of diabetic foot ulcers(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-11-24) Villalba Rodríguez, Angel Manuel; Iqbal, Hafiz Muhammad Nasir; RR/tolmquevedo; Escuela de Ingeniería y Ciencias; Campus Monterrey; Parra-Saldívar, RobertoIn the present, diabetic foot ulcers are a very common pathology all around the world, and most products in the market offer to solve a specific need for the patient such as battling infection or allowing wound debridement. In such regard biomaterial-based nano cues with multi-functional characteristics have been engineered with high interests around the globe. The ease in fine tunability with maintained compliance makes an array of nanocomposite biomaterials outstanding candidates for the biomedical sector of the modern world. In this context, the present work intends to tackle the necessity of alternatives for the treatment of diabetic foot ulcers through the formulation of nanoclay/polymer-based nanocomposite hydrogels. Laponite RD, a synthetic 2-Dimensional nanoclay that becomes inert when in physiological environment, while mixed with water, becomes a clear gel with interesting shear-thinning properties. Optimization of the hydrogel formulation is approached by preparing the samples at several concentration ratios (Nanoclay-Chitosan and Nanoclay-Gelatin; 35-95% of nanoclay in steps of 15%), where the mechanical properties such as viscosity, shear-thinning and injectability are observed to change. Zero shear viscosity of the samples was calculated by the Cross Model Equation, and was observed to increase for the chitosan samples as the nanoclay ratio increased (3.41x103 - 6.44x104 Pa⋅s at 35-65% of nanoclay, respectively) and then decreasing after that concentration of nanoclay. Gelatin had the opposite behavior, while both formulations having a zero shear viscosity of ~3.5x104 Pa⋅s at 95% of nanoclay. Injection force values of the samples in 3 mL plastic syringes with 20G needles, ranged between 1 and 4 N in average, approximately. Adding Laponite RD to chitosan or gelatin, allows for the modification of mechanical properties of such materials. The setup explored in this research allows for a promising polymeric matrix that can potentially be loaded with active compounds for antibacterial support in foot ulcers, as well as enzymes for wound debridement.
- Combined effect of wounding stress and chitosan treatment on the accumulation of antioxidant phenolic compounds in carrot(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-06-12) Berumen Guerrero, Luis; Jacobo Velázquez, Daniel Alberto; emipsanchez/tolmquevedo; Benavides Lozano, Jorge Alejandro; Senés Guerrero, Carolina; School of Engineering and Sciences; Campus MonterreyThe application of postharvest treatments to fruits and vegetables that improves their health-promoting properties, prior to their processing into value-added foods, is an emerging topic of research. Antioxidant phenolic compounds are bioactive secondary metabolites that can be increased by the application of postharvest treatments in horticultural crops. Chlorogenic acid is the main phenolic compound in carrots, and it possesses potent activity against the metabolic syndrome. Wounding stress has been reported as an effective postharvest treatment to increase chlorogenic acid content in carrots. Likewise, chitosan is another elicitor that induces the secondary metabolism of plants. However, the combined effect of wounding stress and chitosan treatment on the accumulation of phenolic compounds has not been previously reported. In the present study, the effect of postharvest wounding stress applied alone and combined with chitosan, over total and individual phenolic compounds in carrot was investigated. Carrots were wounded to obtain pie-cuts and shreds, and the tissue was further sprayed with a chitosan suspension (0.5% w/v). Whole carrots were used as control. After storage, wounding stress induced a significant increase in total phenolics by 278.9% and 1516.9% for carrot pie-cuts and shreds, respectively, as compared with the control before storage (further referred as CBS), whereas the whole tissue did not show an increase. When chitosan was applied in the tissue the wound-induced accumulation of phenolics was further enhanced, showing increases of 917.4% and 2332.7% for pie-cuts and shreds, respectively, as compared with CBS. Interestingly, after storage whole carrots treated with chitosan showed a significant increase (119.5%) in the total phenolic content as compared with CBS. The major phenolic compounds identified in non-stressed carrot tissue (CBS) was chlorogenic acid (220.6 mg/kg), followed by p-coumaric acid derivative (112.9 mg/kg), p-coumaric acid (99.5 mg/kg), gallic acid (71.8 mg/kg) and protocateuic acid (39.3 mg/kg). After storage, the application of chitosan induced the accumulation of isocoumarin in whole carrots (27.9 mg/kg), which was not detected in CBS. An additional phenolic compound that showed accumulation due to chitosan application in whole carrots were chlorogenic acid, and protocatechuic acid, showing increases of 284.6% and 9.95%, respectively, as compared with CBS. As observed for total phenolics, the accumulation of certain individual phenolics increased with the wounding intensity applied. For carrot pies non-treated with chitosan, phenolics that showed increases in concentration after storage were the chlorogenic acid (670.0%), p-coumaric acid derivative (29.43%). Furthermore, biosynthesis of isocoumarin was also detected in carrot pies (45.9 mg/kg) due to wounding stress. Likewise, other compounds such as p-coumaric acid and protocatechuic acid did not show significant increase after storage of carrot pies, whereas the concentration of gallic acid decreased by 50.1%. On the other hand, shredded carrots non-treated with chitosan, showed higher accumulation of most individual phenolics as compared with carrot pies. In this context, shreds showed increases of chlorogenic acid (3,470.0%), p-coumaric acid derivative (200.8%), and p-coumaric acid (17.2%) as compared with CBS. Likewise, shredded carrots showed a high accumulation of isocoumarin after storage (377.5 mg/kg), which was 723.1% higher than isocumarin content in stored carrot pies. When the two stresses were combined (wounding + chitosan) a synergistic effect on the accumulation of certain phenolic compounds were obtained. For instance, after storage chlorogenic acid increased by 1991.3% and 5069.1% in chitosan treated carrot pies and shreds, respectively; whereas p-coumaric acid derivative increased by 173.7% and 385.6% in chitosan treated carrot pies and shreds, respectively. Similarly, isocoumarin, which was not detected in CBS, showed a high accumulation after storage of chitosan treated carrot pies (413 mg/kg) and shreds (1074.8 mg/kg). Results presented herein demonstrated that the combination of wounding stress and chitosan can be used as an effective strategy to increase the content of antioxidant phenolic compounds in carrots. The stressed carrot tissue treated can be used as raw material to obtain value-added food products or for the extraction and purification of antioxidant phenolic compounds with application in the food and dietary supplement industries.