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This work presents an optimized microwave (MW)-assisted method for the chemical functionalization of porous silicon particles (PSip). 3-(Aminopropyl)triethoxysilane (APTES) was grafted on previously stabilized PSip. The functionalization efficiency was studied and optimized in terms of reaction time (Rt) and reaction temperature (RT) using a central composite design (CCD). The effect of MW irradiation on the surface coverage was found to strongly depend on the PSip surface chemistry, Rt, RT, and percentage of APTES. Quantification of grafted amino groups was performed by the ninhydrin method (NHIM); confirming the results by thermogravimetric analysis (TGA). Reacting with 5% APTES solution at 95 °C for 26 min was the best functionalization conditions. The efficiency of PSip-APTES prepared under the optimized conditions was compared to those functionalized by the traditional method; MW irradiation increases by 39% the number of functional groups grafted onto the PSip surfaces with the additional benefit of having a drastic reduction in Rt.

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 this work, it is proven that a biochar obtained from a commercial gasifier can be used as electrode material for supercapacitors (SC). This biochar was produced at 1000 °C from corn cob wastes (GAS), and was compared to an activated biochar obtained in a traditional lab pyrolysis process (LAB). Both biochars were characterized by different physicochemical techniques, observing their amorphous nature with well-developed microporosity dependent of their pretreatment and production methodology. Furthermore, a computational modeling based on Molecular Dynamics at the ReaxFF level was also performed to elucidate the geometry of the resulting microporous structure after simulated pyrolysis. X-ray structure and pore size distribution are in agreement with those results obtained via computational simulation. Both carbon materials were electrochemically evaluated in acidic electrolyte using 3 and 2 electrode systems, obtaining capacitances of 130 F g $$^{-1}$$ (20 mV s $$^{-1}$$ ), and excellent performance compared to commercial activated carbons, with only about 10 $$\%$$ of capacitance loss after 5000 cycles. However, GAS performance in SC was higher than activated biochar due to its higher micropore volume. This study provides a novel useful application to use gasifier residues from agricultural biomass waste for energy storage devices.

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.

Gold nanoparticles (AuNP) stimulate immune responses in mammals but they have not been tested in species of relevance in aquaculture. In this study the immunostimulant and protective potential of orally administered AuNP against V. parahaemolyticus, the causative agent of Acute Hepatopancreatic Necrosis Disease, was determined in shrimp. Synthetized AuNP (18.57 ± 4.37 nm) were moderately dispersed with a negative ζ potential of −10.3 ± 0.208 mV (pH = 7). AuNP were administered (single dose) at 0.2, 2, and 20 μg/g feed in shrimp. Hemolymph samples were withdrawn daily for 6 days. Hemolymph or hemocytes were used to determine total hemocyte counts, immune-related enzymatic activities, and expression of immune-relevant genes. Hepatopancreas was sampled for the analysis of AuNP biodistribution and histological examination. Survival was recorded daily. No mortality or toxicity signs in hepatopancreas were found. AuNP were detected in hepatopancreas. Early (24–48 h) immunostimulation was mainly related to immune gene up-regulation. Upon a challenge with V. parahaemolyticus, survival was higher (80%) and histopathological damages were lower in shrimp treated with the 2 μg/g dose when compared to the control. Therefore orally administered AuNP are proposed as immunostimulants that protect shrimp against V. parahaemolyticus infection.

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

This paper reports an alternative pickling method for rust removal on metallic surfaces using poly(acrylic acid) and poly(acrylic acid-co-itaconic acid). Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR), thermogravimetry (TGA), static light scattering (SLS), and scanning electron microscopy (SEM) were performed to determine polymer and copolymers formation, thermal properties, molecular weights, and the morphological analysis of polymers, respectively. Through an experimental design, polymers’ response was determined in terms of the synthesis parameters. It was observed that both the initiator and the monomers’ molar ratio significantly affect the value of the polymers’ molecular weight. In contrast, for the rust removal, only the initiator had influence. The rust removal process was carried out by the carboxylic acid groups’ adhesion properties, which interacted with the oxidized plates’ polar hydroxyl groups. This method provides an effective and environmentally friendly way to rust removal on metallic surfaces compared with traditional.

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, calcium fluoride (CaF2) and Tb3+-doped calcium fluoride (CaF2:Tb3+) thin films were prepared by electrochemical methods. According to EDS and XRD results, CaF2 thin films undergo through a phase transformation from cubic CaF2:Tb3+ to NaTbF4 when Tb3+ concentration in the electrolytic bath is increased. So that, peaks showed a very clear shifting towards lower angles. On the other hand, optical absorption results showed the typical range of transparency from IR to UV, and from photoluminescence (PL) spectra results it can be observed that it is possible to identify the f-f transition of Tb3+. The PL at low temperature allows finding the quenching concentration when the PL intensity decreases at the highest doping concentration value. However, the results also showed that the transition of Tb3+ does not seem to be affected by the coexistence of the secondary phases such as cubic NaTbF4. In the case of RE-doped CaF2 thin films materials, they can be used with a double purpose for solar cell applications, not only as antireflecting coating, but also as a host for lanthanide doping for down conversion of light. These properties could be very useful for photovoltaic applications, so that the spectral range of light conversion could be increased to achieve higher conversion efficiency values.

Introduction: The development of more efficacious vaccines, especially subunit vaccines administered via non-invasive routes, is a priority in vaccinology. Nanogels are materials that can meet the requirements to serve as efficient vaccine delivery vehicles (in terms of thermo-sensitivity, biocompatibility, and pH-responsiveness; among others); thus there is a growing interest in exploring the potential of nanogels for vaccine development. Areas covered: Herein, a critical analysis of nanogel synthesis methodologies is presented and nanogel-based vaccines under development are summarized and placed in perspective. Promising vaccine candidates based on nanogels have been reported for cancer, obesity, and infectious diseases (mainly respiratory diseases). Some of the candidates were administered by mucosal routes which are highly attractive in terms of simple administration and induction of protective responses at both mucosal and systemic levels. Expert opinion: The most advanced models of nanogel-based vaccines comprise candidates against cancer, based on cholesteryl pullulan nanogels evaluated in clinical trials with promising findings; as well as some vaccines against respiratory pathogens tested in mice thus far. Nonetheless, the challenge for this field is advancing in clinical trials and proving the protective potential in test animals for many other candidates. Implementing green synthesis approaches for nanogels is also required.

This study reports biosynthesis of gold-nanoparticles (AuNPs) by using β-d-glucans isolated from the yeast Yarrowia lypolitica D1. β-d-glucans serve as reducing and stabilizing mediators that induce the formation of AuNPs on the outer surface of the own β-d-glucan. The systems were physicochemically characterized by ultraviolet visible (UV-Vis) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and dynamic light scattering (DLS) analyses. The results revealed the generation of AuNPs with quasi-spherical shape or large one dimension (1D) gold-nanostructures (AuNSs) depending on the HAuCl4 concentration. A cytotoxic study was assessed in mouse splenocytes. Contrary to that expected, important cytotoxicity was found in all β-d-gluc+AuNPs systems by an oxidative stress increase. This study discusses the cytotoxic mechanism, suggesting that the resulting β-d-gluc+AuNPs systems may not be candidates for the formulation of immunostimulants or nanocarriers for biomedical applications.

Recently, the use of chemical warfare agents (CWAs) during terrorist attacks has been intensified affecting mainly civilian population around the world. Since these events are impossible to predict or prevent, the only plausible solution is to design and synthesize novel materials that allow developing more effective portable on-site sensors which at the same time could be produced at low cost in industrial scale. Nanomaterials for their outstanding properties have become ideal candidates for developing emergent platforms applied to the detection of toxic agents and biological threats. The goal of this chapter is to provide an updated overview of the latest research focused on the use of nanotechnology for developing CWAs sensors.

The innovative synthesis of a bio-based poly(acrylic acid) (PAA) and Schizochytrium sp. was performed for the first time. Schizochytrium sp. whole biomass (SCZ) and the insoluble cell fraction (cell wall) (FIP) were used as precursors for the synthesis of the copolymer. Infrared spectroscopy, thermogravimetry, and scanning electron microscopy were performed to determine copolymer formation, thermal properties, and morphology. The new hybrid biopolymers’ thermal and mechanical properties were found to be dependent on microalgae biomass type and concentration. Transition temperature (Tg) of the hybrid PAA-SCZ biopolymers decreased when increasing microalgae percentage, while the opposite occurred for PAA-FIP. It was evaluated the maximum mechanical strength and elongation capacity of PAA-SCZ and PAA-FIP at room temperature and 50 °C. The elongation percentage of the obtained copolymer raised 2–7 times upon increasing the algal biomass concentration. Flexibility increased 3–4 fold when using FIP instead of SCZ. The entire biomass and the cell wall induced structural changes in the hybrid biopolymers similar to those observed in elastomers. A hydrolytic assessment revealed a high swelling capacity (30000 %) for PAA-SCZ hybrid polymer when exposed to physiological conditions (pH 7.4). In terms of these new properties, they can be suitable for biological and environmental applications.

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.

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 not only on 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 roughness of (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.

Although vaccination has prevented millions of deaths, the development of highly immunogenic subunit vaccines is still required. Since the number of adjuvants approved for human use is limited, the new paths for the development of delivery vehicles offered by nanotechnology are of key relevance. Areas covered: Herein, the potential of silica nanoparticles (SP) as both adjuvants and vaccine delivery vehicles is discussed based on the analysis of the current biomedical literature. Expert commentary: SP are reported not only as biodegradable and biocompatible material but also as easy to modify and with a low production cost. Additionally, several reports suggest that SP enhance the immune response. Therefore, SP are a promising delivery vehicle and/or adjuvant in vaccines. However, knowledge on the industrial production and specific aspects of immunity are still required.

Porous silicon (PSi) combines the potential of miniaturization with a very large surface area. The PSi surface can be chemically modified resulting in a high sensitivity (low detection threshold) device for chemical and biomolecular sensing. In previous work, we have shown that redox proteins and fluorescent ligands can be infiltrated into PSi (PSiMc) structures. The hybrid devices have shown interesting new properties produced by the coupling of the individual properties of PSi nanostructures and the modifiers. In this work, we have obtained a PSiMc/redox protein bioelectrode, which presents a quasi-reversible electrochemical response. This effect was attributed to the semiconducting nature of the PSi substrate and to the functional groups of the crosslinking molecules (MPTS), which together produce a capacitive effect on the device. On the other hand, the chemical modification of PSiMc with fluorescent ligands allowed us to fabricate fluorescent PSi hybrid nanostructures, which were tested for the detection of environmental pollutants such as heavy metals (specifically Hg2+). We found that the selectivity of this optical device depends on the selected recognizing molecule. The captured metal induces the formation of a metallic complex that shows higher fluorescence compared with the sensor device. These results demonstrate the viability of using porous silicon as optical sensors and electrochemical biosensors. The infiltration of fluorescent recognizing molecules and proteins into the PSi matrix were evaluated by specular reflectance, FTIR spectroscopy, fluorescence spectroscopy and cyclic voltammetry.

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.

Research on nanometer-sized luminescent semiconductors and their biological applications in detectors and contrasting agents is an emergent field in nanotechnology. When new nanosize technologies are developed for human health applications, their interaction with biological systems should be studied in depth. Rare-earth elements are used in medical and industrial applications, but their toxic effects are not known. In this work, the biological interaction between terbium-doped gadolinium oxysulfide nanoparticles (GOSNPs) with human peripheral blood mononuclear cells (PBMC), human-derived macrophages (THP-1), and human cervical carcinoma cell (HeLa) were evaluated. The GOSNPs were synthetized using a hydrothermal method to obtain monodisperse nanoparticles with an average size of 91 ± 9 nm. Characterization techniques showed the hexagonal phase of the Gd2 O2 S:Tb3+ free of impurities, and a strong green emission at λemi = 544 nm produced by Tb3+ was observed. Toxic effects of GOSNPs were evaluated using cell viability, apoptosis, cell-cycle progression, and immunological response techniques. In addition, an Artemia model was used to assess the toxicity in vivo. Results indicated cell apoptosis in both types of cells with less sensitivity for PBMC cells compared to HeLa cells. In addition, no toxic effects were observed in the in vivo model of Artemia. Moreover, GOSNPs significantly reduced the activation and cell-cycle progression of PBMC and HeLa cells, respectively. Interestingly, an increase in proinflammatory cytokines was not observed. Our data suggest that fluorescence applications of GOSNPs for biolabeling are not toxic in primary immune cells and they may have an immunomodulatory effect. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 605-615, 2017.

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.

Quasi-reversible and direct electrochemistry has been observed at a new electrochemical interface constructed by functionalization of porous silicon microcavities (PSiMc) with either amino (APTES) or mercapto (MPTS) propyltriethoxysilane and the redox protein cytochrome c (cyt c). The high specific surface area, tunable pore size (observed by scanning electron microscopy) and functional surface of PSiMc permitted the infiltration of molecular binders and cyt c into the porous structure. The optical response of PSiMc was evaluated during all modification steps. In all the cases a red shift in the reflectance spectra after substrate modification was observed, indicating the infiltration and immobilization of organic binders and the cyt c protein. Dose-response curves demonstrated that biofunctionalization with APTES followed by glutaraldehyde (GTA) amine activation provides higher amounts of immobilized protein with 4.73 nmol protein/cm 2 of etching area compared with 1 nmol protein/cm 2 when using MPTS as a molecular binder. Infrared spectroscopy (FTIR) also demonstrated the adsorption of the protein within the surface nanostructure. The PSiMc/cyt c hybrid devices showed high electrochemical stability due to the retaining of the protein's redox activity even after several months of its immobilization

In this work we propose a new method to produce a fluorescent chemical sensor for mercury detection (Hg(II)). This device is mainly based on the optical properties of porous silicon nanostructures (PSi) [1] coupled with the fluorescent properties of Rhodamine B [2] (Rh-urea-Ph-urea-Si) ligand derivative, which is covalently linked to PSi acting as receptor of metal ions. The Rh-urea-Ph-urea-Si (Ph=Phenil) compound was synthesized and its complexing ability was studied in liquid phase and solid by fluorescence spectrometry. The results showed that the fluorescence response of the metallic complex is metal concentration dependent. If the Hg(II) concentration increases, the florescence intensity also increases to reach the saturation point of the fluorophore. The electrochemical etching of crystalline silicon wafer [3] produced the PSi transducers, which in turn were functionalized with the organic receptors. The ligand infiltration into the PSi matrix and the metal coordination on the hybrid substrate were evaluated by specular reflectance, infrared and fluorescence spectroscopy, and SEM. Fluorescence microscopy confirmed the qualitative detection of Hg(II) ions due to the increase of the fluorescence observed after metal capture. The changes in electrical impedance upon porous silicon samples before and after the chemical modification, allowed us to obtain the approximate surface area of the porous devices. During the presentation of this work, the Hg (II) detection through voltammetric techniques will be discussed. Acknowledgements. This work was supported by the CONACYT, Project No. CB-153161 and 169634. P Mayela De la Cruz thanks the CONACYT Scholarship: 237466. We acknowledge to Olga Dávalos Montoya for FTIR support and Prof. Jaime Ruiz for the facilities provided for the use of the fluorescent microscope. References. [1] A. Melek, D. Wissem, M. Ghrib, C. Radhouane, Ezzaouia. Journal of Luminescence. 132 (2012) 277-281. [2] Zhisheng Wu, Xuanjun Wu, Yuhui Yang, Ting-bin Wen, Shoufa Han, Bioorganic & Medicinal Chemistry Letters. 22 (2012) 6358–6361. [3] G. Palestino, M. Martin, V. Agarwal, R. Legros, T. Cloitre, László Zimanyi, C. Gergely, Phys. Status Solidi C. 6(7) (2009) 1624-1628

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.

AgNPs have been used to manufacture nanomaterials with new biophysical properties and functions. However, few experimental approaches have been used to assess their potential toxic or beneficial effects on human health, in association with the size, concentration, and biological target. The aim of this work was to evaluate the effects of the AgNPs on the smooth muscle of rat trachea. A single administration of AgNPs did not modify the smooth muscle tone, but, when the trachea rings were pre-treated with acetylcholine (ACh), AgNPs produced a contractile effect. Simultaneous administration of AgNPs and ACh resulted in a slight increase of smooth muscle contractility induced by ACh. AgNPs pretreatment followed by ACh administration showed that AgNPs exerted an important contraction effect induced by ACh after which muscle tone did not return to the basal level. This effect was associated with an increase in the production of nitric oxide (NO). The contractile response of the AgNPs induced by ACh was completely blocked when the rings were incubated, after the ACh but before the AgNPs administration, with 1400 W (NO blocker). The contractile effect was also abolished by atropine, which suggests that AgNPs alter ACh muscarinic receptor signaling. These data also show that AgNPs modify the contractile action of ACh through NO production and possibly induce hyper-reactivity of tracheal smooth muscle.