RESUMEN

To develop a clean-up material suitable for high-fat food matrices for detecting mycotoxins in yak ghee, an octadecyl-bonded hectorite (Hectorite@NHCO(CH2)17CH3) was synthesized through multi-step chemical reactions. A modified QuEChERS-HPLC-MS/MS method for detecting ten mycotoxins in sesame oil in yak ghee was established using Hectorite@NHCO(CH2)17CH3 as clean-up agent. It involved extracting mycotoxin contaminants using acidified acetonitrile and employing the Hectorite@NHCO(CH2)17CH3 to remove interfering substances from the extract. The purified samples were then analyzed using HPLC-MS/MS. Within a linear range of 1.0-500 µg/kg, there was a good linear relationship between the quantification ion peak area of the target analytes and the corresponding concentrations (R2 ≥ 0.9991). The limit of detection (LOD) ranged from 0.10 µg/kg to 18.62 µg/kg and the limit of quantitation (LOQ) ranged 0.32-62.07 µg/kg. The recoveries at low, medium and high concentrations (25, 100 and 500 µg/kg) ranged from 72.2% to 113.9%, with relative standard deviations (RSD) between 3.2% and 17.5%. The intra-day and inter-day precision met experimental requirements. The proposed method was characterized by a high accuracy and precision, and it could cater to the current demand for detecting ten mycotoxins in yak ghee.

RESUMEN

The development of fluorescent materials that can act as sensors for the determination of metal ions in biological fluids is important since they show, among others, high sensitivity and specificity. However, most of the molecules that are used for these purposes possess a very low solubility in aqueous media, and, thus, it is necessary to adopt some derivation strategies. Clay minerals, for example, hectorite, as natural materials, are biocompatible and available in large amounts at a very low cost that have been extensively used as carrier systems for the delivery of different hydrophobic species. In the present work, we report the synthesis and characterization of a hectorite/phenanthroline nanomaterial as a potential fluorescent sensor for Zn ion detection in water. The interaction of phenanthroline with the Ht interlaminar space was thoroughly investigated, via both theoretical and experimental studies (i.e., thermogravimetry, FT-IR, UV-vis and fluorescence spectroscopies and XRD measurements), while its morphology was imaged by scanning electron microscopy. Afterwards, the possibility to use it as sensor for the detection of Zn2+ ions, in comparison to other metal ions, was investigated through fluorescent measurements, and the stability of the solid Ht/Phe/Zn complex was assessed by different experimental and theoretical measurements.

RESUMEN

This study presents the synthesis of Hec-g@PS through the innovative surface modification of hectorite via photocatalytic atom transfer radical polymerization (ATRP). Then, PLA/Hec-g@PS nanocomposites films was prepared with Hec-g@PS as additives by blown molding technique. Furthermore, the thermal degradation kinetics and crystallization kinetics during the thermal degradation of PLA based nanocomposites films were investigated with simultaneous rheology and FTIR technology. The findings indicated that the activation energies for PLA and PLA/Hec-g@PS were -54,702.12 J/mol and -107,963.47 J/mol, respectively, demonstrating that Hec-g@PS substantially influenced PLA thermal stability. Additionally, while the crystallization rates of PLA based films decreased with rising degradation temperatures. Quantum chemical calculations revealed that the mode of interaction between Hec-g@PS and PLA was mainly dominated by dispersion, supplemented by electrostatic and induced interactions of -22.2103 kcal/mol, -16.0779 kcal/mol and -5.4954 kcal/mol, respectively. The combination of crystallization kinetics and quantum chemical calculations further confirmed that Hec-g@PS promoted the alignment of PLA molecular chains due to the enhanced interaction force between them. Hec-g@PS functioned as a nucleating agent, facilitating PLA crystallization and effectively mitigated its thermal degradation. Hec-g@PS as a nucleating agent provides valuable insights into the potential application prospects of biodegradable materials, particularly in the fields of biomedicine and packaging.

Asunto(s)

Cristalización , Nanocompuestos , Poliésteres , Reología , Poliésteres/química , Nanocompuestos/química , Espectroscopía Infrarroja por Transformada de Fourier , Cinética , Temperatura , Silicatos/química

RESUMEN

Dental caries, a chronic infectious disease characterized by tooth mineral loss caused by plaque, is one of the major global public health problems. Silver diamine fluoride (SDF) has been proven to be a highly effective anti-caries drug due to its high bacterial inhibition and remineralization ability. However, the SDF solution is unstable, which immensely limits its clinical application. Therefore, new silver-load clay named AgF@Hec was designed by replacing the NH3with hectorite in this study. Fourier transform infrared spectroscopy and x-ray diffraction spectroscopy were employed to confirm the structure of AgF@Hec. Dynamic light scattering analysis was used to reveal the effect of different hectorite concentrations on the stability of AgF@Hec. Moreover, AgF@Hec exhibits significant remineralization and hardness recovery of the initial carious lesions. Bacteriostatic experiments also proved that it has a significant inhibitory effect onA. Viscosus, S. mutans, S. sanguinis, S. salivarius, Lactobacillus sp.and both gram-positive and gram-negative bacteria. We therefore believed that AgF@Hec should be a promising biomaterial that can be applied in the prevention of dental caries.

Asunto(s)

Arcilla , Caries Dental , Compuestos de Amonio Cuaternario , Compuestos de Plata , Plata , Difracción de Rayos X , Caries Dental/prevención & control , Arcilla/química , Compuestos de Plata/química , Compuestos de Plata/farmacología , Espectroscopía Infrarroja por Transformada de Fourier , Compuestos de Amonio Cuaternario/química , Compuestos de Amonio Cuaternario/farmacología , Plata/química , Plata/farmacología , Fluoruros/química , Antibacterianos/farmacología , Antibacterianos/química , Remineralización Dental/métodos , Streptococcus mutans/efectos de los fármacos , Humanos , Dureza , Ensayo de Materiales , Animales , Pruebas de Sensibilidad Microbiana , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Fluoruros Tópicos

RESUMEN

Background: Clay minerals are nanomaterials that have recently been recognized as enabling excipients that can promote cell adhesion, proliferation, and differentiation. When nanoclays are loaded in a 3D polymeric nanostructure, the cell-substrate interaction is enhanced, and other bioactive properties are optimized. Purpose: In this study, hectorite (HEC)- and montmorillonite (MMT)-doped polymeric scaffolds were explored for the treatment of deep and chronic skin lesions. Methods: Scaffolds were manufactured by means of electrospinning and then crosslinked by heating. Physicochemical analyses were correlated with in vitro biopharmaceutical characterization to predict the in vivo fate of the clay-doped scaffolds. Results and Discussion: The addition of MMT or HEC to the polymeric scaffold framework modifies the surface arrangement and, consequently, the potential of the scaffolds to interact with biological proteins. The presence of nanoclays alters the nanofiber morphology and size, and MMT doping increases wettability and protein adhesion. This has an impact on fibroblast behavior in a shorter time since scaffold stiffness facilitates cell adhesion and cell proliferation. Conclusion: MMT proved to perform better than HEC, and this could be related to its higher hydrophilicity and protein adhesion.

Asunto(s)

Nanofibras , Ingeniería de Tejidos , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Nanofibras/química , Arcilla , Adhesión Celular , Proliferación Celular , Poliésteres/química

RESUMEN

In the last years, the use of clay minerals for pharmaceutical purposes has increased due to their interesting properties. Hectorite (Ht) is a clay belonging to the smectite group which has attracted attention for applications in biology, tissue engineering and as drug carrier and delivery system. However, the mechanisms involved in Ht cellular uptake and transport into cells, are still unclear. Herein, we used a labeled Ht (Ht/1Cl) to study both the cellular uptake, by confocal laser scanning microscopy, and internalization pathways involved in the cellular uptake, by various endocytosis-inhibiting studies and fluorescence microscopy. These studies highlighted that Ht can penetrate the cellular membrane, localizing mainly in the cytoplasm. The main intracellular transport mechanisms are the ATP-dependent ones and those where filaments and microtubules are involved. Finally, as proof of concept for the potential of Ht as carrier system, we envisaged the covalent grafting of the anticancer molecule methotrexate (MTX), chosen as model, to obtain the Ht-MTX nanomaterial. The covalent linkage was confirmed by several techniques and the morphology of the obtained nanomaterial was imaged by SEM and TEM investigations. The kinetic release of the drug from the Ht-MTX nanomaterial in physiological conditions was studied as well. Furthermore, cytotoxic studies on different cell lines, namely, HL-60, HL-60R, MCF-7, 5637, UMUC3 and RT112 showed that Ht could be a promising material for anticancer therapy.

Asunto(s)

Portadores de Fármacos , Metotrexato , Arcilla , Metotrexato/farmacología , Silicatos

RESUMEN

Clay materials and nanoclays have gained recent popularity in the vaccinology field, with biocompatibility, simple functionalization, low toxicity, and low-cost as their main attributes. As elements of nanovaccines, halloysite nanotubes (natural), layered double hydroxides and hectorite (synthetic) are the nanoclays that have advanced into the vaccinology field. Until now, only physisorption has been used to modify the surface of nanoclays with antigens, adjuvants, and/or ligands to create nanovaccines. Protocols to covalently attach these molecules have not been developed with nanoclays, only procedures to develop adsorbents based on nanoclays that could be extended to develop nanovaccine conjugates. In this review, we describe the approaches evaluated on different nanovaccine candidates reported in articles, the immunological results obtained with them and the most advanced approaches in the preclinical field, while describing the nanomaterial itself. In addition, complex systems that use nanoclays were included and described. The safety of nanoclays as carriers is an important key fact to determine their true potential as nanovaccine candidates in humans. Here, we present the evaluations reported in this field. Finally, we point out the perspectives in the development of vaccine prototypes using nanoclays as antigen carriers.

RESUMEN

Halloysite is an aluminosilicate clay with a predominantly hollow tubular structure (HNTs) able to act as a nanocontainer for the encapsulation of several chemicals. However, HNTs possess low affinity for metal ions in their pristine form and they need to be modified for improving their adsorption capabilities. Therefore, to overcome this issue herein we report a straightforward approach for the covalent modification of the external surface of halloysite nanotubes with hectorite clay. Compared to halloysite, hectorite possesses a lamellar structure with higher cation exchange capacity. The covalent linkage between the two clays was verified by several techniques (FTIR spectroscopy, 13C CP-MAS NMR, TGA, ζ-potential, DLS, and XRD measurements) and the morphology was imaged by TEM investigations. As proof of concept the adsorption ability of the obtained nanomaterial in comparison to pristine clays was proved using ciprofloxacin and silver ions chosen as models for their different chemical characteristics.

RESUMEN

A novel g-C3N4/TiO2/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti3+ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C3N4/TiO2/hectorite was 0.01705 min-1, which is approximately 5.38 and 4.88 times that of P25 and g-C3N4, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e-) and holes(h+). The F element from Hectorite causes the formation of Vo and Ti3+ in TiO2, making it responsive to visible light. The effective separation of e- and h+ mainly results from Z-scheme transfer of photo-produced electrons in g-C3N4/TiO2 interface. The composites can be easily recycled and the degradation rate of the RhB still reached 84% after five cycles, indicating its good reusability.

RESUMEN

Patch tests are highly recommended in eczema patients with eyelid involvement. Sunscreen constitutes a potential cause of eyelid or facial allergic contact dermatitis, and should be considered in patients with refractory eczema on these locations. We report a patient sensitized to several emerging allergens such as bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), Scutellaria baicalensis extract, and propylene glycol with an eyelid dermatitis. Patch tests to the combined ingredients propylene carbonate, cyclopentasiloxane, and disteardimonium hectorite; and talc, Cl 77 491, and dimethicone/methicone copolymer were also positive. We highlight the importance of systematically patch testing with the cosmetics brought in by our patients, as well as with the individual ingredients whenever positive. The identification of emerging allergies to new compounds in cosmetics mainly depends on this practice.

Asunto(s)

Dermatitis Alérgica por Contacto/etiología , Enfermedades de los Párpados/inducido químicamente , Fenoles/efectos adversos , Extractos Vegetales/efectos adversos , Propilenglicol/efectos adversos , Triazinas/efectos adversos , Adulto , Femenino , Humanos , Pruebas del Parche , Scutellaria baicalensis

RESUMEN

Sodium alginate (SA) is a linear biopolymer, which is the nontoxic, biodegradable, and rich in carboxyl and hydroxyl groups. In the paper, the SA-based hydrogel bead was prepared by the cationic hectorite clay and anionic sodium alginate with a simple ionic gelation method under freeze-drying, and the adsorption properties were evaluated by the removal of copper ions from aqueous solutions. The composites were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET), thermal analysis (TG), and Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Temkin models were applied to describe the adsorption isotherms. The results showed that the adsorption process was found to follow the Freundlich isotherm model and the maximum sorption capacity was observed to be 160.28 mg/g under the initial concentration from 10 to 700 mg/L at 45 °C. Adsorption kinetics data fitted well with pseudo-second-order rate model. The porous structure of the composite was responsible for the adsorption of Cu2+ ions. But the adsorption ability could be improved by pH. Finally, the adsorption mechanism was suggested. Graphical abstract.

Asunto(s)

Alginatos/química , Cobre/aislamiento & purificación , Silicatos/química , Adsorción , Arcilla/química , Cobre/química , Hidrogeles/química , Concentración de Iones de Hidrógeno , Cinética , Modelos Químicos , Porosidad , Espectroscopía Infrarroja por Transformada de Fourier , Termogravimetría , Agua/química , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Difracción de Rayos X

RESUMEN

Herein, we report the formation and properties of a rare example of high-performance composite membranes from polybisbenzimidazobenzophenanthroline-dione (BBB) that do not sustain a flame or burn with smoke nor show melt dripping. In addition, this material possesses a low density and very high thermal stability (char yield as high as 80-94%), strength, and flexibility. Such membranes are highly desirable for battery separators, protective clothing, construction, and automobiles. Because BBB is an insoluble and infusible polymer, the composite membranes were made using a bottom-up vacuum-assisted self-assembly method with an aqueous dispersion of short BBB fibers and Hec. The use of water as the solvent, upscalability, and excellent flame retardancy in combination with low density, flexibility, and low thermal conductivity of the composite membranes make the preparation method and membranes highly promising for future use in real applications.

RESUMEN

Currently, there are few strategies for controlling pathogenic bacteria, especially the pathotypes of Escherichia coli which are an emerging threat to public health worldwide. Here, multivalent vaccine formulations are reported for control of pathogenic E. coli. The formulations utilised clay nanoparticles, either layered double hydroxides (LDH) or hectorite (HEC), to complex with a cocktail of three recombinant antigens, intimin ß (IB), proprietary antigen 1 (PAg1) and proprietary antigen 2 (PAg2). Acting as nano-adjuvants, LDH and HEC were able to stimulate strong, durable and balanced immune responses in mice. Moreover, LDH-IB-PAg1-PAg2 and HEC-IB-PAg1-PAg2 immunised mice developed potent mucosal immune responses and efficiently prevented adherence of enterohemorrhagic E. coli serotype O26 to mammalian cells. Notably, the multi-faceted immune responses elicited by the clay nanoparticle formulations were significantly higher than those induced by a QuilA formulation, without antigenic competition observed for the first time. The results of this study suggest that LDH and HEC offer considerable promise as effective multivalent vaccine carriers against important pathogens such as enteropathogenic E. coli.

Asunto(s)

Adhesinas Bacterianas/administración & dosificación , Antígenos Bacterianos/administración & dosificación , Arcilla , Proteínas de Escherichia coli/administración & dosificación , Vacunas contra Escherichia coli/administración & dosificación , Hidróxidos/administración & dosificación , Nanopartículas/administración & dosificación , Silicatos/administración & dosificación , Adhesinas Bacterianas/química , Adsorción , Animales , Anticuerpos Antibacterianos/sangre , Antígenos Bacterianos/química , Arcilla/química , Escherichia coli/inmunología , Infecciones por Escherichia coli/prevención & control , Proteínas de Escherichia coli/química , Femenino , Hidróxidos/química , Inmunoglobulina G/sangre , Ratones Endogámicos C57BL , Nanopartículas/química , Silicatos/química

RESUMEN

Nanomaterials have been widely tested as new generation vaccine adjuvants, but few evoke efficient immunoreactions. Clay nanoparticles, for example, layered double hydroxide (LDH) and hectorite (HEC) nanoparticles, have shown their potent adjuvanticity in generating effective and durable immune responses. However, the mechanism by which clay nanoadjuvants stimulate the immune system is not well understood. Here, it is demonstrated that LDH and HEC-antigen complexes form loose agglomerates in culture medium/serum. They also form nodules with loose structures in tissue after subcutaneous injection, where they act as a depot for up to 35 d. More importantly, clay nanoparticles actively and continuously recruit immune cells into the depot for up to one month, and stimulate stronger immune responses than FDA-approved adjuvants, Alum and QuilA. Sustained antigen release is also observed in clay nanoparticle depots, with 50-60% antigen released after 35 d. In contrast, Alum-antigen complexes show minimal antigen release from the depot. Importantly, LDH and HEC are more effective than QuilA and Alum in promoting memory T-cell proliferation. These findings suggest that both clay nanoadjuvants can serve as active vaccine platforms for sustained and potent immune responses.

Asunto(s)

Antígenos/metabolismo , Arcilla/química , Inmunidad Humoral , Nanopartículas/química , Animales , Antígenos/ultraestructura , Bovinos , Proliferación Celular , Femenino , Inmunización , Memoria Inmunológica , Ratones Endogámicos C57BL , Nanopartículas/ultraestructura , Tamaño de la Partícula , Albúmina Sérica Bovina/metabolismo , Linfocitos T/citología

RESUMEN

Several 2:1 layer silicates comprising di- and trioctahedral smectites of different layer charge between 0.2 and 0.4 per formula unit and a trioctahedral vermiculite were studied by an in situ method that allowed Fourier transform infrared spectroscopy (FTIR) spectra and water vapor sorption isotherms to be obtained simultaneously. The particle size and shape of the selected materials were determined using X-ray diffraction and gas adsorption analyses, which provided an estimate of the particle size with resulting edge site proportion. The aim of this study was to elucidate the hydration mechanism in 2:1 layer silicates during desorption and adsorption of water vapor. Domains in the desorption and adsorption of water vapor of the smectite samples with a slightly increasing slope were explained by a heterogeneous layer charge distribution, which enables the coexistence of different hydration states even under controlled conditions. Whereas hysteresis was observed over the entire isothermal range of the smectites, the isotherm of the vermiculite sample only showed hysteresis in the transition from the monohydrated state (1W) to the bihydrated state (2W). We also revealed that hysteresis is a function of the layer charge distribution, the achieved water content, and the particle size with resulting edge site contribution. Increasing the edge site proportions led to an increased hysteresis. The findings from the experimental FTIR/gravimetric analysis showed that the transition from 2W to 1W and backward is visible using infrared spectroscopy. The shifting of δ(H-O-H) was influenced by the layer charge and octahedral substitutions. As a final point, we use water as a sensor molecule to describe the OH groups of the octahedral sheet and show that the observed shifts result from a change in the tilting angle. Our experimental results were supported by ab initio thermodynamic simulations that revealed the different shifting behavior of δ(H-O-H) and δ(M x+-OH-N y+) related to the differences in surface charge density and octahedral compositions.

RESUMEN

Improved strategies are urgently required to control infections with enterohemorrhagic Escherichia coli and enteropathogenic E. coli, two dominant zoonotic enteric pathogens responsible for a wide spectrum of illnesses as well as deaths of human being, with tremendous financial cost worldwide. The present study investigates the capacity of two clay nanoparticles (NPs) with opposite surface charges, namely synthetic layered double hydroxide (LDH) and hectorite (HEC) NPs as adjuvants to promote strong immune responses against the infections. Here both LDH and HEC NPs are showed to be able to carry an appreciable amount of Intimin ß (1.1 and 4.4 mg per mg clay nanomaterials, respectively) and significantly facilitate antigen uptake by antigen-presenting cells. Remarkably, these clay NPs induce strong antibody and cell-mediated immune responses, which are much higher than that by the potent adjuvant, QuilA. Furthermore, these strong immune responses are well maintained for at least four months in the mouse model, during which there are no changes in histopathology of the animal organs. Collectively these data demonstrate the suitability of LDH and HEC NPs as useful adjuvants in new-generation vaccine formulations to control various infectious diseases.

Asunto(s)

Adhesinas Bacterianas/inmunología , Silicatos de Aluminio/química , Proteínas de Escherichia coli/inmunología , Vacunas contra Escherichia coli/inmunología , Escherichia coli/inmunología , Nanopartículas/química , Animales , Formación de Anticuerpos/inmunología , Células Presentadoras de Antígenos/metabolismo , Antígenos Bacterianos/metabolismo , Arcilla , Endocitosis , Ensayo de Immunospot Ligado a Enzimas , Inmunidad Celular/inmunología , Inmunización , Interferón gamma/metabolismo , Ratones Endogámicos C57BL

RESUMEN

In this work, a new and facile method was introduced to prepare molecularly imprinted polymers (MIPs) based on nano clay hectorite (Hec) for sinomenine hydrochloride (SM) analysis. Hec was firstly dissolved in distilled water in order to swell adequately, followed by a common precipitation polymerization with SM as the template, methacrylic acid as monomer, ethylene glycol dimethacrylate as a crosslinker and 2,2-azobisisobutyronitrile as an initiator. Hec@SM-MIPs were characterized by Fourier transform infrared spectrometer, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The maximum binding capacity of Hec@SM-MIPs, SM-MIPs and non-imprinted polymers (NIPs) (Hec@NIPs) was 57.4, 16.8 and 11.6 mg/g, respectively. The reason for this result may be that Hec@SM-MIPs have more binding sites and imprinted cavities for template molecule. Equilibrium data were described by the Langmuir and Freundlich isotherm models. The results showed that the Hec@SM-MIPs adsorption data correlated better with the Langmuir equation than the Freundlich equation under the studied concentration range. In vitro drug release experiment, Hec@SM-MIPs have a better ability to control SM release than SM-MIPs. Therefore, Hec@SM-MIPs were successfully applied to extraction of SM and used as the materials for drug delivery system.

Asunto(s)

Portadores de Fármacos/química , Portadores de Fármacos/síntesis química , Impresión Molecular , Morfinanos/química , Ácidos Polimetacrílicos/química , Ácidos Polimetacrílicos/síntesis química , Silicatos/química , Adsorción , Liberación de Fármacos , Cinética , Polimerizacion

RESUMEN

The aging of salt-free hectorite suspensions with different concentrations (c(L)=2.9, 3.2 and 3.5 wt%) stored for 2 days or 4 days was studied by rheology at different temperatures. The evolution of storage and loss moduli G' and G″ during aging followed aging time-temperature superposition. The temperature dependence of the shift factor a(T), which reflected the aging kinetics, was interpreted by the reaction-limited colloidal aggregation (RLCA) mechanism with counterion condensation in calculating the double-layer interaction of the charged clay particles. Temperature dependence of the plateau modulus and yield stress of the suspension aged for 800 s was modeled with the soft glassy rheology (SGR) theory. The estimated noise temperature x indicated that the sample aged at higher temperature corresponded to a deeper quench in the nonergodic state. Under larger amplitude of oscillatory shear, the suspension exhibited a strain rate-frequency superposition (SRFS). The shearing eliminated the effects of aging and heating.