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Caries is a multifactorial disease that can negatively affect dental tissues through the demineralization process, which produces acids deriving from the metabolism of carbohydrates. Some strategies to prevent this process have been proposed, such as topical fluoride application, resin-based restorations, pit and fissures sealers, infiltrated resins, vaccines, mouthwashes, and several brushing techniques. Objective. To evaluate in vitro enamel hydrophobic modification as a method of prevention against demineralization. A descriptive and comparative study was carried out. Thirty premolars extracted for orthodontic reasons were obtained, encapsulated in epoxy resin, sectioned, and sanded to obtain specimens 3mm in thickness. The samples were pretreated with NaOCl and EDTA, incubated with 1 and 4% octadeyltrichlorosilane (OTS) or with 3 and 6% octadecyltriethoxysilane (TEOS) for 5min and for 8h. Subsequently, the samples were immersed in citric acid for 2 months. The samples were analyzed by their contact angle, infrared spectroscopy, scanning electron microscopy, atomic and confocal force, before and after treatment in citric acid. The samples coated with 1 and 4% OTS for 5min and 8h kept the silanizing agent on their surface after 2 months in citric acid. The treatment with TEOS was only effective at 6% with a reaction time of 5min. The modification with 1 and 4% OTS protects the surface of the tooth enamel from demineralization in acidic medium. The results indicate that treatment with 4% OTS is effective from 5min, which makes it appropriate in clinical practice. Resumen Introducción. Caries es una enfermedad multifactorial que destruye en tejido dental por la desmineralización de ácidos generados en el metabolismo de carbohidratos. Algunos métodos preventivos, como fluoruro, resinas, selladores de fosetas y fisuras, resinas infiltradas, vacunas, enjuagues bucales, y un sinfín de técnicas de cepillado, han sido empleadas. Objetivo. Evaluar in vitro la modificación hidrofoba del esmalte como método preventivo en contra de la desmineralización. Materiales y Métodos. Un estudio decriptivo y comparativo fue empleado. Se obtuvieron treinta premolares sanos extraidos por razones ortodónticas y encapsulados en resina epóxica, seccionados y pulidos hasta obtener especímenes de 3mm de grosor. Las muestras fueron pretratadas con NaOCl y EDTA, incubadas en octadeciltriclosorilano (OTS) al 1 y 4% y octadeciltrietoxisilano (TEOS) 3 y 6% por 5min y 8h. Después, las muestras fueron sumergidas en ácido cítrico por 2 meses. Las muestras fueron analizadas con ángulo de contacto, espectroscopía infrarroja, microscopía electrónica de barrido, atómica y confocal, antes y después de tratamiento con ácido cítrico. Resultados. Las muestras cubiertas con OTS 1 y 4% por 5min y 8h mantuvieron el agente silanizante sobre la superficie después de 2 meses en ácido cítrico. El tratamiento con TEOS fue efectivo al 6% y con un tiempo de reacción de 5min. Conclusiones. La modificación con 1 y 4% de OTS proteje la superficie del esmalte dental contra la desmineralización en un medio ácido. Estos resultados indican que el tratamiento con OTS 4% es efectivo desde 5min de aplicación, lo cual es apropiado en la práctica clínica.

In the last decade, the publications presenting novel physical and chemical aspects of gadolinium-based oxide (Gd2O3) and oxysulfide (Gd2O2S) particles in the micro- or nano-scale have increased, mainly stimulated by the exciting applications of these materials in the biomedical field. Their optical properties, related to down and upconversion phenomena and the ability to functionalize their surface, make them attractive for developing new probes for selective targeting and emergent bioimaging techniques, either for biomolecule labeling or theranostics. Moreover, recent reports have shown interesting optical behavior of these systems influenced by the synthesis methods, dopant amount and type, particle shape and size, and surface functionality. Hence, this review presents a compilation of the latest works focused on evaluating the optical properties of Gd2O3 and Gd2O2S particles as a function of their physicochemical and morphological properties; and also on their novel applications as MRI contrast agents and drug delivery nanovehicles, discussed along with their administration routes, biodistribution, cytotoxicity, and clearance mechanisms. Perspectives for this field are also identified and discussed.

Nanostructured porous silicon microparticles (μPSip) synthesized by electrochemical etching were used as tunable carriers for sustained delivery of metformin hydrochloride (MET), an oral antihyperglycemic agent. The surface of native PSi microparticles was modified by thermal oxidation to enhance μPSip stability and MET physical adsorption. Morphological and physicochemical properties of the porous carrier were characterized by a combination of scanning electron microscopy, nitrogen adsorption–desorption, and zeta potential techniques. Drug loading was confirmed by ATR Fourier transform infrared spectroscopy, and loading efficiency was quantified by thermogravimetric analysis and UV–Vis. From MET released profiles, we demonstrated that thermally oxidized µPSip exhibited a sustained release during 26 h, with burst effect depending on pH of the microenvironment. Native PSi loaded particles showed a complete MET release within 6 h with a substantial burst effect at 1 h. The loading kinetics of MET at different initial concentrations were satisfactorily predicted with a 3D diffusional model based on surface diffusion. The proposed model showed that the surface diffusion coefficient (Ds) values increase exponentially as a function of MET loading. The mass transport parameters obtained from the loading kinetics were used to predict the release kinetics of MET. The comparison of experimental and predicted results showed an accurate representation of the data, highlighting the reliability of the model. Through in vivo studies, it was demonstrated that MET-μPSip microcarriers did not induce inflammatory processes. A sustained hypoglycemic effect was observed for 24 h after composite administration, which is a novel contribution of this work.

In this study, we introduce a novel route to produce down and upconverting Eu3+/Yb3+ co-doped oxysulfide nanorods, which display strong red emission at 620 nm under Vis (460 nm) or NIR (976 nm) wavelength excitation. An in-depth analysis of the synthesis parameters such as lanthanides concentration, type of nucleating agent, reaction temperature, and the reaction pressure was performed to determine their influence in the morphology and photoluminescence properties. It was demonstrated that as a nucleating agent, ethanolamine is a good substitute of the commonly used triethylamine providing the advantage of using lower toxicity reagents. The Transmission Electron Microscopy (TEM), Infrared (FTIR) and Zeta Potential analysis showed that the chemical surface of nanorods evolve during thermal and sulfidation processes without producing morphological changes. The intensity of light emission during downconversion (DC) and upconversion (UC) phenomena was found to be doping ions concentration dependent. The highest DC light emission was found at a Yb3+/Eu3+ concentration ratio of 0.25, while the most intense UC luminescence was found at 4. Conversely, quenching of DC and UC was observed when using Yb3+/Eu3+ concentration ratios of 4 and 0.25 respectively, indicating that luminescent centers are strongly affected in both processes by the chemical environment but also for the ions doping ratio. It was demonstrated that two-photon absorption is the primary mechanism for the red emission in the UC process.

Mesoporous silica nanoparticles (MSNPs) were synthesized and loaded with metformin hydrochloride (Metf), its adsorption has studied at different concentrations and pHs, optimal adsorption conditions were determined. Hybrid MSNPs-Metf were mixed with chitosan to compress them and form quasi-spherical pellets, were coated with five chitosan layers as a barrier to prolong metformin release. It showed that this pellet is useful for metformin controlled release since drug over time was significantly delayed by the chitosan coating and then, as metformin is electrostatically linked to MSNPs, it also controls the release of drug, releasing 170 mg after 17 h of exposure at pH 1.2. When pH is >1.2, metformin release was significantly prolonged. Since 170 mg is 21% of a 850-mg metformin dose and previous studies report that 90% of metformin is recovered as unchanged drug in urine after 12 h of metformin intakes. These results suggest that MSNPs-Metf pellets, coated with chitosan, are an option to avoid excessive metformin ingest.

La eficiencia, el costo y la estabilidad son las tres características más importantes que un dispositivo fotovoltaico debe cumplir para poder considerarse como posible producto comercial. En los últimos años un nuevo tipo de celdas ha captado el interés de la comunidad científica, cuyo componente principal es una perovskita híbrida orgánica-inorgánica. Los dispositivos estudiados han logrado eficiencias hasta de 20%, empleando métodos de depósito sencillos. Estos grandes avances se han logrado con el empleo de la perovskita CH3NH3PbI3 como material absorbedor de radiación, sin embargo, debido a su naturaleza, estas celdas carecen de una estabilidad confiable. En este trabajo se emplea la técnica de blow-drying como un método alterno para obtener películas delgadas de CH3NH3PbI3 a partir de soluciones con diferente concentración, empleando aire caliente (25% humedad relativa, 90 °C) como gas de arrastre y condiciones de humedad controlada durante la formación de los depósitos. Mediante FTIR se verificó la química superficial de los depósitos, los cuales mostraron cierta hidratación cuando se empleó aire a 25 °C, misma que fue eliminada al emplear aire caliente. Además, los depósitos obtenidos por esta técnica consistieron en estructuras entrecruzadas conformadas por pequeños gránulos, de acuerdo con lo observado mediante MEB. La cobertura de los sustratos estuvo influenciada por la concentración de las soluciones empleadas para obtener los depósitos, obteniendo un mejor recubrimiento al emplear una solución de concentración 0.434 M. Por otro lado, se estudió la estabilidad de los depósitos obtenidos al ser expuestos a ambientes con humedades de 25%. En esta prueba destacó la estabilidad de los depósitos obtenidos empleando una solución 0.434 M, cuya resistencia a la degradación se extendió a más de 12 días en ambientes con 25% de humedad. Stability is still a property that limits the commercialization of perovskite solar cells. Thus, with the development of continuous deposition methods, it is essential to determine their feasibility in terms of stability and the efficiency of the devices produced. In this work, a hot air blow-drying (HABD) method is proposed as an alternative for the deposition of CH3NH3PbI3 (MAPbI) perovskite thin-films. The ability of HABD to produce homogeneous and stable thin-films was systematically studied and compared with those produced with air at standard conditions (25 °C, 25% relative humidity). The MAPbI thin-films were characterized by infrared spectroscopy and X-ray diffraction revealing that air temperature rules the film hydration. Partial degradation after using air at standard conditions was observed in contrast with the stable and pure perovskite phase obtained when using air heated at 90 C°. The influence of solution concentration on the surface coverage was determined by scanning electron and atomic force microscopies. It was found that 4 μL of precursors solution (0.434 M) produced a homogeneous MAPbI thin-film with ~180 nm thickness and smooth surface (Rq ~ 29 nm) covering a 6.25 cm2 area. Moreover, the outstanding optical and electrical properties of MAPbI were not affected by the deposition procedure. Remarkably, degradation tests demonstrate that our HABD method is capable of producing stable MAPbI thin-films with excellent resistance to degradation at ambient conditions (up to 15 days), which makes it a promising low-cost and easy to use method for the continuous fabrication of perovskite solar cells. Administradores Investigadores Estudiantes

A poly(acrylic acid-co-itaconic acid) (PAA-co-IA)/NaOH hydrogel containing bamboo-type multiwall carbon nanotubes (B-MWCNTs) doped with nitrogen (PAA-co-IA/NaOH/B-MWCNTs) was synthesized and characterized by SEM, absorption of water, point of zero charges, infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The possible use of the PAA-co-IA/NaOH/B-MWCNT hydrogel as an electrode modifier and pre-concentrator agent for Cd(II) sensing purposes was then evaluated using carbon paste electrodes via differential pulse voltammetry. The presence of the B-MWCNTs in the hydrogel matrix decreased its degree of swelling, stabilized the structure of the swollen gel, and favored the detection of 3 ppb Cd(II), which is comparable to the World Health Organization&rsquo, s allowable maximum value in drinking water. A calibration curve was obtained in the concentration range of 2.67 &times, 10&minus, 8 to 6.23 &times, 7 M (i.e., 3 and 70 ppb) to determine a limit of detection (LOD) of 19.24 &mu, gL&minus, 1 and a sensitivity of 0.15 &mu, C ppb&minus, 1. Also, the Zn(II), Hg(II), Pb(II) and Cu(II) ions interfered moderately on the determination of Cd(II).

The development of vaccines is a crucial response against the COVID-19 pandemic and innovative nanovaccines could increase the potential to address this remarkable challenge. In the present study a B cell epitope (S461–493) from the spike protein of SARS-CoV-2 was selected and its immunogenicity validated in sheep. This synthetic peptide was coupled to gold nanoparticles (AuNP) functionalized with SH-PEG-NH2 via glutaraldehyde-mediated coupling to obtain the AuNP-S461–493 candidate, which showed in s.c.-immunized mice a superior immunogenicity (IgG responses) when compared to soluble S461–493; and lead to increased expression of relevant cytokines in splenocytes cultures. Interestingly, the response triggered by AuNP-S461–493 was similar in magnitude to that induced using a conventional strong adjuvant (Freund's adjuvant). This study provides a platform for the development of AuNP-based nanovaccines targeting specific SARS-CoV-2 epitopes., Graphical Abstract An antigenic peptide from SARS-CoV-2 was selected to prepare a gold nanoparticles-based conjugate (AuNP-S461–493), whose immunogenicity was assessed in mice, revealing an enhanced humoral response when compared with the soluble peptide.Unlabelled Image

The current COVID-19 pandemic caused by the SARS-CoV-2 virus demands the development of strategies not only to detect or inactivate the virus, but to treat it (therapeutically and prophylactically). COVID-19 is not only a critical threat for the population with risk factors, but also generates a dramatic economic impact in terms of morbidity and the overall interruption of economic activities.Advanced materials are the basis of several technologies that could diminish the impact of COVID-19: biosensors might allow early virus detection, nanosized vaccines are powerful agents that could prevent viral infections, and nanosystems with antiviral activity could bind the virus for inactivation or destruction upon application of an external stimulus. Herein all these methods are discussed under the light of cutting-edge technologies and the previously reported prototypes targeting enveloped viruses similar to SARS-CoV-2. This analysis was derived from an extensive scientific literature search (including pubmed) performed on April 2020.Perspectives on how biosensors, vaccines, and antiviral nanosystems can be implemented to fight COVID-19 are envisioned; identifying the approaches that can be implemented in the short term and those that deserve long term research to cope with respiratory viruses-related pandemics in the future.

In this work new gelatin-based porous silicon hydrogel composites were developed. Porous silicon microparticles (PSip) with average size of 3 µm and average pore dimensions of 50 nm were used as crosslinking agents. Thermally oxidized or aldehyde functionalized PSip were mixed with a gelatin biopolymer to obtain physically or chemically cross-linked hydrogel composites. The resulting hydrogel networks showed important property enhancements such as improved mechanical stiffness, higher hydrolytic stability, and swelling capability; attributed to the PSip capacity of producing multiple bonds within the hydrogel network. The gelatin composites were evaluated as drug delivery systems using tramadol (TR) as model drug. Kinetics studies showed a TR release up to 20 h for the physically produced composite and up to 30 h for the chemically produced when compared to the hydrogel controls (5 h). Cytotoxicity studies of oxidized and functionalized PSip demonstrated a cell viability above 85%, which supports the use of gelatin-based PSip composites for drug release by topic or oral routes.

Nowadays, hydrogels have become ideal materials for use in biomedical applications by virtue of their biodegradability and biocompatibility. In this study, poly(ethylene glycol) diamine (PEGD) based hydrogels were synthetized using as crosslinking agents citric acid (CA) or glutaraldehyde (GTA), and gelatin (GEL) as hydrogel vehicle. The hydrogels were studied for drug release in vitro using tramadol (TR) as a model drug. Thermal studies under isothermal and non-isothermal conditions were conducted. The elastic module (G′) showed higher values than the loss module (G′) confirming that the contribution of the elastic segments in both materials is more significant than the viscous ones. Aqueous stability, swelling and drug release properties were determined. The swelling analysis indicated that both hydrogels are temperature dependent. The kinetics studies showed an anomalous drug release mechanism. PEGD:CA/GEL hydrogel behave as an elastic matrix strong enough to maintain the drug dosage.

In this work the single and ternary removal of sulfonamides (sulfamethoxazole, sulfadiazine and sulfametazine) from water was investigated using granular activated carbon. The single adsorption mechanism was elucidated by obtaining the adsorption isotherms supported by computational calculations. The ternary adsorption was analyzed by using an experimental Box-Behnken type response surface design. The results showed that the total adsorption capacity of activated carbon duplicates in ternary systems compared to single systems. Besides, in both cases the activated carbon showed a greater affinity for removing sulfamethoxazole followed by sulfadiazine and sulfametazine, correspondingly. It was shown that hydrogen bonding interactions presented the highest adsorption energies followed by π-π interactions. From the design of experiments three statistically reliable mathematical models were proposed to estimate the adsorption capacity for each sulfonamide as a function of the solution pH, temperature and initial concentration. Finally, it was shown that sulfonamide ternary adsorption is an endothermic process and that the adsorption rate decreases as a result of partial blockage of the pores due to simultaneous adsorption.

New adjuvants are required in the field of vaccinology to enhance the immunogenicity and efficacy of subunit vaccines, which constitute a safer approach to protect against infectious diseases compared to whole pathogen-based vaccines. In the present study, rare-earth upconverting microparticles were explored as possible antigen carriers with adjuvant properties by using a peptide from the Zika virus, an emerging pathogen to which no vaccines are available. The Gd2O3:Tb3+/Er3+ (UpGO) carriers were prepared by hydrothermal synthesis and modified by a reaction with (3-Aminopropyl)triethoxysilane (APTES), in order to introduce reactive amine groups at their surfaces to anchor the ZK2 peptide. The system was fully characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), photoluminescence spectroscopy (PL), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The results showed a stable colloidal system of APTES-UpGO with a high loading capacity of up to 0.480 μg of ZK2 peptide per μg of microparticles. For the in vivo studies, the system was administered to mice by the subcutaneous route and enhanced humoral responses were observed when UpGO was used as the antigen carrier as compared with the group immunized with the peptide alone. The immune response showed a Th2-polarization as revealed IgG subclass analysis. The present study provides new insights into the use of lanthanides-based materials as antigen carriers during vaccine development.

Vaccinology faces the challenge of developing improved immunization approaches that are able to induce long-term immunity with the desired Th profile according to the pathology. In this context, new vehicles for efficient antigen delivery that exert adjuvant effects play a critical role in addressing this goal. Herein, mesoporous silicon particles (PSiP) were assessed as carriers for a peptide-based vaccine targeting the receptor for advanced glycation end products (RAGE), which is a relevant receptor in Alzheimer&acute, s disease and other diseases. A RAGE peptide was adsorbed onto PSiP (PSiP vaccine) and administered to BALB/c mice, leading to immune responses that were similar in magnitude to those induced by the soluble peptide. However, the response induced by PSiP lasted for a significantly longer period when compared with the behavior of the group immunized with the peptide alone. Therefore, PSiP are proposed as carriers to enhance immune memory, which is critical in vaccination. This study opens interesting perspectives related to the application of PSiP in vaccinology.

Terbium-doped gadolinium oxysulfide (Gd 2 O 2 S:Tb 3+ ) nanoparticles were synthesized by using a hydrothermal method followed with a sulfur reaction. We studied parameters such as precursor concentration, stock solutions temperature, reaction time, and reaction temperature to obtain well defined homogeneous particles with specific shape and size. The chemical evolution of the formed particles was followed by the Infrared Spectroscopy (FTIR), thus showing the removal of the hydroxycarbonate precursors at different stages of synthesis. X-ray analysis (WAXD) confirmed that the calcination and sulfidation processes produced cubic (Gd 2 O 3 :Tb 3+ ) and hexagonal (Gd 2 O 2 S:Tb 3+ ) crystalline structures. The photoluminescent (PL) properties were evaluated as a response to UV light excitation in both solid phase and colloidal suspension; we determine the maximum emission intensity as a function of the Tb 3+ ion dopant concentration and determine the limiting amount in the material before quenching occurs. In colloidal suspensions, the emission spectra of both Gd 2 O 3 :Tb 3+ and Gd 2 O 2 S:Tb 3+ were compared, and we observed that the sulfidation process increased the integrated emission intensity seventyfold with respect to the former. To evaluate the particles behavior in aqueous media for possible uses in medical applications, an electrophoretic mobility study was carried out, thus observing that the fluorescence emission depends on the pH of the solution, which in turn correlates with the electrophoretic mobility of the particles.

Photodeposition and impregnation methods for the functionalization of zinc oxide nanoagglomerates with silver nanoparticles were studied. The effect of reaction conditions such as nominal amount of stabilized silver nanoparticles, pH, and time on functionalization efficiency was investigated. The functionalized zinc oxide was characterized by X-ray diffraction, electron microscopy, N2 physisorption, infrared spectroscopy, and UV–vis spectroscopy. The results showed that UV irradiation promoted the homogeneous dispersion of strongly bonded silver nanoparticles on ZnO. In addition, hydroxyl surface content and absorption in the visible region of the spectra suggest improvement of photocatalytic activity. The ZnO functionalized with silver by photodeposition and impregnation methods showed four and two times higher reaction rates, respectively, for bisphenol-A degradation compared with pure ZnO. Hence, the proposed functionalization methods represent a useful approach to synthesizing photocatalysts with the potential to be used in degradation of endocrine-disrupting compounds.

Vaccination is a crucial approach to eradicate and control amyriad of infectious and non-communicable diseases. Subunit vaccines are considered the most convenient approach for vaccine formulation; however, the development of new adjuvants and vaccine delivery vehicles to improve the immunogenicity of such formulations is needed. The authors of this review describe the recent application of porous silicon particles (PSiP) as both a potential vaccine delivery vehicle and adjuvant. PSiP are attractive for this application due to its safety, biodegradability and compatibility for functionalization. Herein, the development of multi-epitope cancer vaccines is discussed as an example on how PSiP are promising materials for the development of innovative vaccines.

Nanomaterials are applied with great success in biomedical applications as templates for the development of new generation devices, which can be used to solve current health problems. These new nanoscale systems are designed with multifunctions to perform specific and selective tasks. One of the most important applications of this new nanotechnology; focuses on developing new systems for the controlled release of drugs, mainly due to their capability to improve the temporal and spatial presentation of drugs in the body and their ability to protect them from physiological degradation or elimination. Hydrogels, porous silicon (PSi), and PSi-composites have been widely adopted in this field due to their biological, morphological, and physicochemical properties; which can be tuned to obtain sensitive responses to physiological stimuli. Despite the fact that some recent academic papers have shown the benefits of these nanomaterials in a wide range of biological applications, more in vivo studies are needed to take these hybrid systems towards clinical trials. In this mini-review some of the hydrogels, PSi, and PSi-composites latest applications and prospects in this field of science are presented.

The photocatalytic degradation of O,O-dimethyl O-p-nitrophenyl phosphorothioate (common name methyl parathion) in aqueous TiO2 suspensions is reported in this study. The aim of this article is to identify the intermediate organic reaction products using a number of analytical techniques, such as UV–vis, HPLC, GC–MS and 1H NMR. Total organic carbon (TOC) and the concentration of inorganic ions in the reaction mixture, as a function of reaction time, are also measured to monitor the mineralization of organic chemical species. Under both, acidic and basic conditions, the primary product is methyl paraoxon, which eventually is degraded to 4-nitrophenol. This aromatic compound is mainly transformed into hydroquinone, which is later oxidized to 1,2,4-benzenetriol. GC–MS studies show that this aromatic triol is preferentially converted via an oxidative pathway into 5-hydroxymethyl-5H-furfuran-2-one. Under basic conditions, methyl parathion is converted via a reaction pathway involving methyl paraoxon, 4-nitrophenol, hydroquinone and aliphatic acids with the resulting species being refractory to be further oxidized and mineralized. On the other hand, under controlled acidic conditions, methyl parathion and various intermediates quickly degrade in a rather fast oxidation process.

International audience; Porous silicon microcavity (PSiMc) structures were used to immobilize photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon based electronics and biological redox systems.

In this work, we report the experimental results and theoretical analysis of strong localization of resonance transmission modes generated by hybrid periodic/quasiperiodic heterostructures (HHs) based on porous silicon. The HHs are formed by stacking a quasiperiodic Fibonacci (FN) substructure between two distributed Bragg reflectors (DBRs). FN substructure defines the number of strong localized modes that can be tunable at any given wavelength and be unfolded when a partial periodicity condition is imposed. These structures show interesting properties for biomaterials research, biosensor applications and basic studies of adsorption of organic molecules. We also demonstrate the sensitivity of HHs to material infiltration.

A rhodamine organosilane derivative (Rh-UTES) has been obtained by one-pot synthesis. The chemical structure of Rh-UTES was confirmed by nuclear magnetic resonance (NMR) and infrared (FTIR) techniques. To obtain an inorganic-organic hybrid sensor, Rh-UTES was covalently immobilized on a porous silicon microcavity (PSiMc) via triethoxysilane groups. The attachment of the organic derivative into PSiMc was confirmed by FTIR, specular reflectance, and scanning electron microscopy (SEM). The optical performance of Rh-UTES receptor for Hg2+ detection was investigated by fluorescent spectroscopy and microscopy. Upon the addition of increasing amounts of Hg2+ ions, a remarkable enhancement in emission intensity was produced in both systems. In the solid phase, an increase of integrated fluorescent emission of 0.12- and 0.15-fold after Hg2+ receptor coordination was observed. The light harvesting capability of PSiMc devices allowed obtaining an enhanced fluorescent emission after Rh-UTES immobilization (277-fold). The fluorescence microscopy of hybrid PSiMc sensor provided an optical qualitative test for Hg2+ detection.

Los pesticidas son sustancias químicas que tienen como objetivo eliminar plagas ya sean animales o vegetales, sin embargo, se ha descubierto que su uso en exceso ha causado una variedad de repercusiones adversas en los humanos y en el ambiente. El alto empleó de pesticidas en la agricultura y su esparcimiento sobre grandes superficies ha provocado que un gran porcentaje de pesticidas se pueda permear afectando cuerpos de agua subterráneos y a su vez también pueda ser arrastrado sobre la superficie, afectando cuerpos de agua superficiales. Debido a esto, la detección y cuantificación de especies químicas contaminantes son primordiales actualmente, ya que se presenta una gran problemática a nivel mundial por contaminación. Por tales motivos el presente proyecto plantea la síntesis de un fluoróforo orgánico inmovilizado en una red polimérica con el objetivo de detectar pesticidas organofosforados. El fluoróforo se sintetizó a partir de adenosín trifosfato y de la molécula fluorescente de naftalimida. Este sensor se evaluó en glifosato (Gli), uno de los herbicidas organofosforados más polémicos en la actualidad por su alto empleó en plantaciones de aguacate en México. La detección se llevó a cabo por un mecanismo de sustitución de la parte de reconocimiento por el contaminante, lo que permitió el cambio de fluorescencia de la solución contaminada con el pesticida. El máximo rango de detección de glifosato fue de 100 a 800 µM, lo cual es excelente para la detección de estos contaminantes en zonas cercanas a plantaciones agrícolas. Se hicieron pruebas de selectividad empleando otros analitos como carbonatos, fosfatos, nitratos y arseniatos, moléculas presentes en altas concentraciones en suelos y aguas, obteniendo una buena selectividad hacia el pesticida objetivo. Pesticides are chemicals that are intended to eliminate pests whether they are animals or plants, nevertheless their overuse has been found to cause a variety of adverse impacts on humans and the environment. The excessive use of pesticides in agriculture and their spread over large natural areas has caused a large percentage of pesticides to permeate affecting underground water and in some cases be dragged on the surface, affecting surface water bodies. Based on these facts, the detection and quantification of polluting chemical species are essential today since there is a great problem worldwide due to contamination. The present project proposes the synthesis of an organic fluorophore immobilized in a polymeric matrix with the objective of sensing organophosphate pesticides. The fluorophore was synthesized from adenosine triphosphate and the fluorescent molecule of naphthalimide. This sensor was evaluated against glyphosate, one of the most controversial organophosphate herbicides due to its high use in avocado plantations in Mexico. The detection was carried out by a substitution mechanism of the sensor, which allowed the change of fluorescence of the solution contaminated with the pesticide. The maximum glyphosate detection range was found to be 100 to 800 µM, which is excellent for detecting these contaminants in areas close to agricultural plantations. Selectivity tests were carried out using other analytes such as carbonates, phosphates, nitrates, and arsenates, obtaining good selectivity towards the target pesticide. Grupos de la comunidad Investigadores Estudiantes

Se estudiaron dos polímeros a base de ácido acrílico. El primero fue un poli(ácido acrílico-co-ácido itacónico)/NaOH, un hidrogel sintético, sintetizado con el propósito de conocer su capacidad de hinchamiento y su capacidad para eliminar óxido de hierro y cobre de superficies metálicas. Se demostró que la formación del copolímero y la neutralización de los grupos carboxílico mejoraron la capacidad de eliminación de óxido y su capacidad de hinchamiento. La remoción máxima de óxido de hierro fue de 269 mg g−1 de hidrogel, valor cuatro veces mayor que el reportado en la literatura. El segundo hidrogel fue un polímero innovador de base biológica de ácido acrílico y Schizochytrium sp. realizado por primera vez. La célula completa de Schizochytrium sp. (SCZ) y su fracción celular insoluble (FIP) se utilizaron como precursores para la polimerización. Se realizaron espectroscopía infrarroja (FTIR), termogravimetría (TGA) y microscopía electrónica de barrido (SEM) para determinar la formación del copolímero, las propiedades térmicas y su morfología. Las propiedades térmicas y mecánicas de los nuevos hidrogeles híbridos dependieron del tipo y concentración de la biomasa de microalgas. La temperatura de transición vítrea (Tg) de los biopolímeros disminuyó al aumentar el porcentaje de Schizochytrium sp., mientras que ocurrió lo contrario para el polímero con FIP. La resistencia mecánica máxima de los biopolímeros fue del 715% de elongación y se encontró a 50 ºC. El alargamiento del polímero de base biológica aumentó de 2 a 7 veces al aumentar la concentración de biomasa de microalgas. La flexibilidad aumentó de 3 a 4 veces cuando se utilizó su pared celular insoluble en lugar de la célula completa. Una evaluación hidrolítica reveló la capacidad máxima de hinchamiento (30000%) cuando se expone a condiciones fisiológicas (pH 7,4). En términos de sus propiedades, estos polímeros de base biológica pueden ser adecuados para aplicaciones biológicas y ambientales. Two polymers based on acrylic acid were studied. The first one was a poly(acrylic acid-co-itaconic acid)/NaOH, a synthetic hydrogel, synthetized with the purpose to discover its swelling capacity and its ability to remove iron and copper rust from metallic surfaces. It was proven that copolymer formation and neutralization of carboxylic acid groups highly improved the rust removal capabilities and its swelling ability. The maximum iron rust removal was 269 mg g−1 of hydrogel, a value which is four times greater than that reported in literature. The second hydrogel was an innovative bio-based polymer of acrylic acid and Schizochytrium sp. performed for the first time. The whole cell of Schizochytrium sp. (SCZ) and its insoluble cell fraction (FIP) were used as precursors for the polymerization. Infrared spectroscopy (FTIR), thermogravimetry (TGA), and scanning electron microscopy (SEM) were performed to determine the copolymer formation, the thermal properties, and its morphology. The new hybrid hydrogels’ thermal and mechanical properties were dependent on the microalgae biomass type and concentration. The temperature of glass transition (Tg) of the biopolymers decreased when increasing Schizochytrium sp. percentage, while the opposite occurred for polymer with FIP. The maximum mechanical strength of the biopolymers was 750 % of elongation and was found at 50 ºC. The elongation of the bio-based polymer raised 2–7 times upon increasing the microalgal biomass concentration. Flexibility increased 3–4 fold when using its insoluble cell wall instead of whole cell. A hydrolytic assessment revealed the maximum swelling capacity (30000 %) when exposed to physiological conditions (pH 7.4). In terms of their properties, these bio-based polymers can be suitable for biological and environmental applications.