RESUMEN

Electrophotonic (EPh) circuits are novel systems where photons and electrons can be controlled simultaneously in the same integrated circuit, attaining the development of innovative sensors for different applications. In this work, we present a complementary metal-oxide-semiconductor (CMOS)-compatible EPh circuit for biotin sensing, in which a silicon-based light source is monolithically integrated. The device is composed of an integrated light source, a waveguide, and a p-n photodiode, which are all fabricated in the same chip. The functionalization of the waveguide's surface was investigated to biotinylate the EPh system for potential biosensing applications. The modified surfaces were characterized by AFM, optical microscopy, and Raman spectroscopy, as well as by photoluminescence measurements. The changes on the waveguide's surface due to functionalization and biotinylation translated into different photocurrent intensities detected in the photodiode, demonstrating the potential uses of the EPh circuit as a biosensor.

Asunto(s)

Técnicas Biosensibles , Biotina , Silicio/química , Diseño de Equipo , Técnicas Biosensibles/métodos , Semiconductores

RESUMEN

MIS-type structures composed of silicon-rich oxide (SRO), thin films deposited by hot filament chemical vapor deposition (HFCVD), show interesting I-V and I-t properties under white light illumination and a response as photodetectors. From electrical measurements, it was found that at a reverse bias of -4 V, the illumination current increased by up to three orders of magnitude relative to the dark current, which was about 82 nA, while the photogenerated current reached a value of 25 µA. The reported MIS structure with SRO as the dielectric layer exhibited a hopping conduction mechanism, and an ohmic conduction mechanism was found with low voltage. I-t measurements confirmed the increased photogenerated current. Furthermore, the MIS structure, characterized by current-wavelength (I-λ) measurements, exhibited a maximum responsivity value at 254 mA/W, specific detectivity (D*) at 2.21 × 1011 cm Hz1/2 W-1, and a noise equivalent power (NEP) of 49 pW at a wavelength of 535 nm. The structure exhibited good switching behavior, with rise and fall times between 120 and 150 ms, respectively. These rise and decay times explain the generation and recombination of charge carriers and the trapping and release of traps, respectively. These results make MIS-type structures useful as photodetectors in the 420 to 590 nm range.

Asunto(s)

Gases , Silicio , Calor , Silicio/química , Dióxido de Silicio

RESUMEN

Previous studies have reported silicone oil (SO) applied to needles and syringes in the vitreous of patients after intravitreal injections. We evaluated four syringes (SR 1-mL insulin, Saldanha-Rodrigues; BD 1-mL Tuberculin Slip Tip, Becton-Dickinson; BD Ultra-Fine 0.3 mL, HSW Norm-Ject Tuberculin, Henke Sass Wolf) and 10 needles (BD PrecisionGlide 27- and 30-gauge (G); BD Eclipse and JBP Nanoneedle 27-, 30-, 33- and 34-G; TSK Invisible Needle and 27 and 30-G Steriject Control Hub). The protein-free buffer samples injected into the syringes and needles under study were collected in an Eppendorf tube and taken to Flow imaging microscopy, that characterized the concentration and morphology of the microsized particles. The number of particles was analyzed. The coefficients of variation (CV) were the primary outcome. The Feltz and Miller test compared the CVs. The significance level was 5%. Numerous particles and high CVs were associated with both devices, needles and syringes; the comparisons among them did not reach significance. The BD Ultrafine 0.3 mL syringe (149.7%) had the highest CV and the SO-free HSW Norm-Ject (66.4%) syringe the lowest, and the TSK Invisible needle (149.5%) had the highest and the BD Precision Glide 30G needle (35.9%) needle the lowest. In conclusion, particle release, including those with SO morphology, varied greatly among instruments, even from the same lots, which is relevant considering that fewer particles are injected into some eyes compared with others.

Asunto(s)

Agujas , Silicio/química , Aceites de Silicona/química , Jeringas , Reproducibilidad de los Resultados

RESUMEN

Immobilization of PEG-covered silicon dots, PEGSiDs, on glass substrates was performed following a simple strategy involving particle embedding by a sol-gel process forming a silica film on glass slides. The obtained films, denoted as fSiO x -PEGSiD, constitute a water-wettable, strongly supported, photoluminescent glass coating. The films showed high capacity for photosensitizing singlet oxygen (1O2) in the UVA when immersed in water. Staphylococcus aureus colonies formed on fSiO x -PEGSiDs modified glasses revealed the inhibition of bacterial adhesion and bacterial growth leading to the formation of loosely-packed and smaller S. aureus colonies. Upon 350 nm light irradiation of the biofilmed fSiO x -PEGSiDs -modified glasses, S. aureus growth was inhibited and bacteria killed reducing the number of living bacteria by three orders of magnitude. Eradication of attached bacteria was achieved by the synergistic effect exerted by a less adherent fSiO x -PEGSiDs surface that inhibits biofilm formation and the ability of the surface to photosensitize 1O2 to kill bacteria.

Asunto(s)

Biopelículas/efectos de los fármacos , Fármacos Fotosensibilizantes/farmacología , Silicio/farmacología , Oxígeno Singlete/farmacología , Staphylococcus aureus/crecimiento & desarrollo , Adhesión Bacteriana/efectos de los fármacos , Sinergismo Farmacológico , Vidrio , Viabilidad Microbiana/efectos de los fármacos , Fármacos Fotosensibilizantes/química , Polietilenglicoles/química , Puntos Cuánticos , Silicio/química , Dióxido de Silicio/química , Oxígeno Singlete/química , Staphylococcus aureus/efectos de los fármacos , Humectabilidad

RESUMEN

Nickel nanopillar arrays were electrodeposited onto silicon substrates using porous alumina membranes as a template. The characterization of the samples was done by scanning electron microscopy, X-ray diffraction, and alternating force gradient magnetometry. Ni nanostructures were directly grown on Si by galvanostatic and potentiostatic electrodeposition techniques in three remarkable charge transfer configurations. Differences in the growth mechanisms of the nanopillars were observed, depending on the deposition method. A high correlation between the height of the nanopillars and the charge synthesis was observed irrespective of the electrochemical technique. The magnetization measurements demonstrated a main dependence with the height of the nanopillars. The synthesis of Ni nanosystems with a controllable aspect ratio provides an effective way to produce well-ordered networks for wide scientific applications.

Asunto(s)

Óxido de Aluminio/química , Galvanoplastia , Níquel/química , Silicio/química , Campos Magnéticos , Porosidad , Difracción de Rayos X

RESUMEN

The interactions in model ionic YTX3···Z (Y = NC, F, Cl, Br; X = F, Cl, Br, Z = F-, Cl-, Br-, Li+) dyads containing the tetrel atoms, T = C, Si, Ge, were studied using ab initio computational methods, including an energy decomposition analysis, which found that the YTX3 molecules were stabilized by both anions (via tetrel bonding) and cations (via polarization). For the tetrel-bonded dyads, both the electrostatic and polarization forces make comparable contributions to the binding in the C-containing dyads, whereas, electrostatic forces are by far the largest contributor to the binding in the Si- and Ge-containing analogues. Model metastable Li+···NCTCl3···F- (T = C, Si, Ge) triads were found to be lower in energy than the combined energy of the Li+ + NCTCl3 + F- fragments. The pair energies and cooperative energies for these highly polar triads were also computed and discussed.

Asunto(s)

Química/métodos , Iones , Electricidad Estática , Aniones , Cationes , Flúor/química , Germanio/química , Enlace de Hidrógeno , Ligandos , Litio/química , Modelos Moleculares , Conformación Molecular , Distribución Normal , Teoría Cuántica , Silicio/química

RESUMEN

Artificial membranes are models for biological systems and are important for applications. We introduce a dry two-step self-assembly method consisting of the high-vacuum evaporation of phospholipid molecules over silicon, followed by a subsequent annealing step in air. We evaporate dipalmitoylphosphatidylcholine (DPPC) molecules over bare silicon without the use of polymer cushions or solvents. High-resolution ellipsometry and AFM temperature-dependent measurements are performed in air to detect the characteristic phase transitions of DPPC bilayers. Complementary AFM force-spectroscopy breakthrough events are induced to detect single- and multi-bilayer formation. These combined experimental methods confirm the formation of stable non-hydrated supported lipid bilayers with phase transitions gel to ripple at 311.5 ± 0.9 K, ripple to liquid crystalline at 323.8 ± 2.5 K and liquid crystalline to fluid disordered at 330.4 ± 0.9 K, consistent with such structures reported in wet environments. We find that the AFM tip induces a restructuring or intercalation of the bilayer that is strongly related to the applied tip-force. These dry supported lipid bilayers show long-term stability. These findings are relevant for the development of functional biointerfaces, specifically for fabrication of biosensors and membrane protein platforms. The observed stability is relevant in the context of lifetimes of systems protected by bilayers in dry environments.

Asunto(s)

Membrana Dobles de Lípidos/química , Membranas Artificiales , Microscopía de Fuerza Atómica/métodos , Silicio/química , 1,2-Dipalmitoilfosfatidilcolina/química , Transición de Fase , Fosfolípidos/química , Temperatura , Vacio , Volatilización

RESUMEN

Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.

Asunto(s)

Azospirillum brasilense/fisiología , Nitrógeno/química , Silicio/química , Suelo/química , Zea mays/crecimiento & desarrollo , Productos Agrícolas/química , Fertilizantes , Hojas de la Planta/crecimiento & desarrollo , Raíces de Plantas/crecimiento & desarrollo , Semillas/crecimiento & desarrollo , Estrés Fisiológico/fisiología

RESUMEN

This work aimed to develop cantilever nanobiosensor functionalized with tyrosinase enzyme to detect 17ß-estradiol and estrone hormones. In this system, the tyrosinase enzyme was covalently immobilized by self-assembled monolayer onto the cantilever sensor surface. It was possible to verify that the high hormone concentration investigated resulted in high voltage response. The nanobiosensor presented a distinction between the concentrations evaluated and was verified sensitivities of 0.497 and 0.101 V/µg, limit of detection of 0.1 and 0.4 ng/L for the hormones 17ß-estradiol and estrone, respectively. The device showed good reversibility and during 30 days of storage maintained about 99% of the original signal. The cantilever nanobiosensor applied in different water samples (ultrapure, river, tap, and mineral) showed good performance, so could be readily extended toward the on-site monitoring of the other trace small molecular pollutants in environmental water matrices.

Asunto(s)

Técnicas Biosensibles , Monitoreo del Ambiente/instrumentación , Monitoreo del Ambiente/métodos , Estradiol/análisis , Estrona/análisis , Monofenol Monooxigenasa/química , Nanopartículas/química , Contaminantes Químicos del Agua/análisis , Contaminantes Ambientales/análisis , Límite de Detección , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Nanotecnología , Ríos , Silicio/química , Esteroides , Propiedades de Superficie , Agua/química

RESUMEN

Hypervalent tellurium compounds have a particular reactivity towards thiol compounds which are related to their biological properties. In this work, this property was assembled to tellurium-functionalized surfaces. These compounds were used as linkers in the immobilization process of thiolated biomolecules (such as DNA) on microcantilever surfaces. The telluride derivatives acted as reversible binding agents due to their redox properties, providing the regeneration of microcantilever surfaces and allowing their reuse for further biomolecules immobilizations, recycling the functional surface. Initially, we started from the synthesis of 4-((3-((4-methoxyphenyl) tellanyl) phenyl) amino)-4-oxobutanoic acid, a new compound, which was immobilized on a silicon surface. In nanomechanical systems, the detection involved a hybridization study of thiolated DNA sequences. Fluorescence microscopy technique was used to confirm the immobilization and removal of the telluride-DNA system and provided revealing results about the potentiality of applying redox properties to chalcogen derivatives at surfaces.

Asunto(s)

Técnicas Biosensibles , ADN/química , Silicio/química , Telurio/química , Secuencia de Bases/genética , Nanoestructuras/química , Hibridación de Ácido Nucleico , Compuestos de Sulfhidrilo/química , Propiedades de Superficie

RESUMEN

We describe the use of a hybrid magnetic nanocomposite (HMNC) for the extraction and purification of plasmid DNA (pDNA) from Escherichia coli aqueous solutions. The HMNC, which was synthesized via emulsion polymerization, was characterized by transmission electron microscopy, scanning electron microscopy, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering and magnetic measurements. The results confirmed the incorporation of polyaniline (Pani) in its conducting form onto a core formed by the magnetic iron oxide, with the hybrid particles presenting an average size of (95 ±â€¯30) nm and a saturation magnetization of 30 emu/g. The yield, purity and quality of the pDNA purified by using the Pani HMNC were evaluated by UV-Vis spectroscopy, agarose gel electrophoresis, and Polymerase Chain Reaction (PCR), respectively. An average yield of ~6.9 µg was obtained in the DNA extraction process, with the collected material presenting a good purity (a ₳260/280 ratio in the 1.68-1.82 range) and an excellent quality, as confirmed by subsequent PCR assays. Hence, this HMNC appears as a promising material for use in pDNA purification protocols, and we suggest that this novel HMNC-based methodology can be of general interest and find widespread application in different biomedical procedures.

Asunto(s)

Compuestos de Anilina/química , ADN/química , Compuestos Férricos/química , Magnetismo , Nanocompuestos/química , Plásmidos , Silicio/química

RESUMEN

AIM: Amino functionalization is a first step modification aiming to achieve biomedical applications of silicon nanoparticles, for example, for photodynamic therapy or radiotherapy. Nevertheless, toxicity and low quantum yields due to the positive charge of amino groups emerge as a problem that could be solved with subsequent derivatizations. MATERIALS & METHODS: Folic and PEG-conjugated nanoparticles were obtained from amino-functionalized silicon nanoparticle (NH2SiNP). Cytotoxicity was determined on a tumor cell line at low and high concentrations. Four end points of in vivo toxicity were evaluated on zebrafish (Danio rerio). RESULTS: Folic acid functionalization reduced the cytotoxicity in comparison to amino and PEG-functionalized nanoparticles. In zebrafish, folic functionalization lowered toxicity in general while PEG increased it. CONCLUSION: Functionalization of NH2SiNP with folic acid reduced the toxic effects in vitro and in vivo. This could be useful for therapeutic applications. PEG functionalization did not lower the toxicity.

Asunto(s)

Ácido Fólico/química , Nanopartículas/química , Polietilenglicoles/química , Animales , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Sistemas de Liberación de Medicamentos/métodos , Ácido Fólico/farmacología , Nanopartículas/toxicidad , Silicio/química , Silicio/toxicidad , Pez Cebra

RESUMEN

The roles of the anode material, boron-doped diamond (BDD), with different boron (B) and substrate Silicon (Si) or Niobium (Nb) content, and one dimensionally stable anode (DSA®), were evaluated in the oxidation of norfloxacin (NOR) by electrochemical advanced oxidation process (EAOP). The effect of other components in real wastewater on the performance of EAOP was also studied. The anode materials were characterized by cyclic voltammetry, regarding diamond quality, electro-generation of oxidants and NOR oxidation mechanism (direct and/or indirect). The results showed that the anode material influences on the NOR oxidation pathway, due to distinct characteristics of the substrate and the coating. Apparently, low difference in diamond-sp³/sp2-carbon ratio (Si/BDD100 × Si/BDD2500) does not leads to significant differences in the EAOP. On the other hand, the variation in the sp³/sp2 ratio seems to be higher when Si/BDD2500 and Nb/BDD2500 are compared, which would explain the best current efficiency result for Si substrate. However, the Nb substrate presented a similar current efficiency and a 60% lower energy consumption. Dissolved organic matter (DOM) present in the real wastewater affect the EAOP-Nb/BDD due to HO and persulfate ions scavenged. However, when supporting electrolyte was added to a real wastewater spiked with NOR, the NOR decay reaches similar values found to the synthetic one. Due to the energy saving and mechanical properties, Nb substrate presents some technological advantages in relation to Si, which can facilitate the application to industrial levels.

Asunto(s)

Técnicas Electroquímicas/métodos , Niobio/química , Norfloxacino/química , Aguas Residuales/química , Antibacterianos/química , Boro/química , Electrodos , Oxidantes , Oxidación-Reducción , Silicio/química , Agua/química , Contaminantes Químicos del Agua/química

RESUMEN

Silicon blue-emitting nanoparticles (NPs) are promising effectors for photodynamic therapy and radiotherapy, because of their production of reactive oxygen species (ROS) upon irradiation. RESULTS: Amino-functionalized silicon NPs (NH2SiNP) were intrinsically nontoxic below 100 µg/ml in vitro (on two tumor cell lines) and in vivo (zebrafish larvae and embryos). NH2SiNP showed a moderate effect as a photosensitizer for photodynamic therapy and reduced ROS generation in radiotherapy, which could be indicative of a ROS scavenging effect. Encapsulation of NH2SiNP into ultradeformable liposomes improved their skin penetration after topical application, reaching the viable epidermis where neoplastic events occur. CONCLUSION: Subsequent derivatizations after amino-functionalization and incorporation to nanodrug delivery systems could expand the spectrum of the biomedical application of these kind of silicon NPs.

Asunto(s)

Sistemas de Liberación de Medicamentos , Nanopartículas/química , Fármacos Fotosensibilizantes/administración & dosificación , Silicio/administración & dosificación , Animales , Supervivencia Celular/efectos de los fármacos , Humanos , Liposomas/administración & dosificación , Liposomas/química , Nanopartículas/administración & dosificación , Fotoquimioterapia , Fármacos Fotosensibilizantes/química , Especies Reactivas de Oxígeno/metabolismo , Silicio/química , Pez Cebra/crecimiento & desarrollo

RESUMEN

Porous silica-based materials are attractive for biomedical applications due to their biocompatibility and biodegradable character. In addition, inorganic supports such as porous silicon are being developed due to integrated circuit chip compatibility and tunable properties leading to a wide range of multidisciplinary applications. In this contribution, biosilica extracted from a rarely studied plant material (Equisetum Myriochaetum), its conversion to silicon and the potential for both materials to be used as supports for enzyme immobilization are investigated. E. myriochaetum was subject to conventional acid digestion to extract biogenic silica with a% yield remarkably higher (up to 3 times) than for other Equisetum sp. (i.e. E. Arvense). The surface area of the isolated silica was ∼400 m2/g, suitable for biotechnological applications. Biogenic silicon was obtained by magnesiothermic reduction. The materials were characterized by SEM-EDX, XRD, FT-IR, ICP-OES, TGA and BET analysis and did not contain significant levels of class 1 heavy elements (such as Pb, Cd, Hg and As). Two commercial peroxidases, horseradish peroxidase (HRP) and Coprinus cinereus peroxidase (CiP) were immobilized onto the biogenic materials using three different functionalization routes: (A) carbodiimide, (B) amine + glutaraldehyde and (C) amine + carbodiimide. Although both biogenic silica and porous silicon could be used as supports differences in behaviour were observed for the two enzymes. For HRP, loading onto biogenic silica via the glutaraldehyde immobilization technique (route B) was most effective. The loading of CiP showed a much higher peroxidase activity onto porous silicon than silica functionalized by the carbodiimide method (route A). From the properties of the extracted materials obtained from Equisetum Myriochaetum and the immobilization results observed, these materials appear to be promising for industrial and biomedical applications.

Asunto(s)

Enzimas Inmovilizadas/química , Equisetum/química , Dióxido de Silicio/química , Silicio/química , Porosidad

RESUMEN

We developed a highly sensitive silicon platform, suitable to assess the molecular organization of protein samples. Prototype platforms were obtained using different electrochemical protocols for the electrodeposition of Ag-nanoparticles onto the hydrogenated silicon surface. A platform with high Surface Enhanced Raman Scattering efficiency was selected based on the surface coverage and the number density of particles size distribution. The performance of the platform was determined by studying the interaction of Myristoylated Alanine-Rich C Kinase Substrate (MARCKS) protein with the substrate according to its molecular organization. The chemical and structural characteristics of MARCKS molecules were examined under two configurations: i) a disordered distribution given by a MARCKS solution drop deposited onto the platform and, ii) a compact monolayer transferred to the platform by the Langmuir-Blodgett method. Raman spectra show vibrational bands of Phenylalanine and Lysine residues specific for the protein effector domain, and evidence the presence of alpha helix structure in both configurations. Moreover, we distinguished the supramolecular order between the compact monolayer and random molecular distribution. The platforms containing Ag-nanoparticles are suitable for studies of protein structure and interactions, advancing a methodological strategy for our long term goal, which is to explore the interaction of proteins with model membranes.

Asunto(s)

Sustrato de la Proteína Quinasa C Rico en Alanina Miristoilada/química , Espectrometría Raman/métodos , Galvanoplastia , Humanos , Nanopartículas del Metal/química , Conformación Proteica en Hélice alfa , Dominios Proteicos , Silicio/química , Plata/química , Propiedades de Superficie

RESUMEN

There are many chronic diseases related with inflammation. The chronic inflammation can produce other problems as cancer. Therefore, it is necessary to design drugs with better anti-inflammatory activity than those in the clinic. Likewise, these could be used in chronic treatments with minimum adverse effects. The amide or ester functionality in combination with the insertion of a silyl alkyl moiety is able to improve some drug properties. In this context, the evaluation of a group of silicon containing ibuprofen derivatives (SCIDs) as antioxidants and anti-inflammatory agents is reported. Antioxidant activity was evaluated by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH⨪), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS•+) and the Fe(II) chelating ability methods. The anti-inflammatory activity was determined by using the carrageenan induced rat paw edema. The gastrotoxic profile of the SCIDs that displayed significant anti-inflammatory activity was determined by the indomethacin induced ulceration method. The SCIDs performed better than ibuprofen as chelating agents for Fe(II) and as scavengers for the free radicals DPPH• and ABTS•+. On the anti-inflammatory test, compound 4a inhibited the edema up to 87%, while 4d &10b achieved significant inflammation inhibition at a lower effective dose 50 (ED50) than ibuprofen´s. None of the SCIDs endowed with anti-inflammatory activity, showed significant gastrotoxic effects with respect to those displayed by ibuprofen. Based on the experimental results and aided by the theoretical docking approach, it was possible to rationalize how the SCIDs may bind to cyclooxygenase isoforms and helped to explain their reduced gastrotoxicity. The evaluated effects were improved in SCIDs with respect to ibuprofen.

Asunto(s)

Simulación por Computador , Ibuprofeno/química , Ibuprofeno/farmacología , Silicio/química , Animales , Antiinflamatorios/química , Antiinflamatorios/metabolismo , Antiinflamatorios/farmacología , Antioxidantes/química , Antioxidantes/metabolismo , Antioxidantes/farmacología , Benzotiazoles/química , Compuestos de Bifenilo/química , Dominio Catalítico , Ciclooxigenasa 2/química , Ciclooxigenasa 2/metabolismo , Ibuprofeno/metabolismo , Quelantes del Hierro/química , Quelantes del Hierro/metabolismo , Quelantes del Hierro/farmacología , Masculino , Simulación del Acoplamiento Molecular , Picratos/química , Ratas , Ratas Wistar , Ácidos Sulfónicos/química

RESUMEN

Organic silicon (OS), glucosamine sulfate (GS), and methylsulfonylmethane (MSM) have been related to bone and connective tissue health and have been considered as basic therapy for osteoarthrosis disorders. Therefore, the aim was to analyze the effect of the association of these three components in mandibular bone defects in rats. Nine rats were used for histocompatibility test. In each animal was implanted the composition (70% OS, 15% GS, 15% MSM) and gutta percha (control) under the dorsal subcutaneous tissue. The samples were collected at 7, 14, and 21 days post-surgery and inflammatory events analyzed. In sequence, the composition was engrafted in mandibular bone defects of nine rats; bone defects without treatment were the control group. Analyses were performed at 7, 14, and 28 days post-surgery and samples were evaluated by scanning electron microscopy (SEM). For the histocompatibility test, both groups had a moderate inflammatory process at 7 days post-surgery and mild inflammatory process at 14 and 21 days. But in SEM analysis, the composition promotes an extensive reabsorption in cortical and crest alveolar bone, and great tooth root reabsorption. In conclusion, although the composition had positive result in the histocompatibility test, its direct application in mandibular bone defects caused intense resorption.

Asunto(s)

Regeneración Ósea/efectos de los fármacos , Dimetilsulfóxido/administración & dosificación , Glucosamina/administración & dosificación , Mandíbula/efectos de los fármacos , Silicio/administración & dosificación , Sulfonas/administración & dosificación , Animales , Regeneración Ósea/inmunología , Dimetilsulfóxido/uso terapéutico , Glucosamina/uso terapéutico , Masculino , Mandíbula/inmunología , Mandíbula/patología , Microscopía Electrónica de Rastreo , Prótesis e Implantes , Ratas , Silicio/química , Silicio/uso terapéutico , Sulfonas/uso terapéutico , Cicatrización de Heridas/efectos de los fármacos

RESUMEN

In this work, porous-silicon samples were prepared by electrochemical etching on p-type (B-doped) Silicon (Si) wafers. Hydrofluoric acid (HF)-ethanol (C2H5OH) [HF:Et] and Hydrofluoric acid (HF)-dimethylformamide (DMF-C3H7NO) [HF:DMF] solution concentrations were varied between [1:2]-[1:3] and [1:7]-[1:9], respectively. Effects of synthesis parameters, like current density, solution concentrations, reaction time, on morphological properties were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements. Pore sizes varying from 20 nm to micrometers were obtained for long reaction times and [HF:Et] [1:2] concentrations; while pore sizes in the same order were observed for [HF:DMF] [1:7], but for shorter reaction time. Greater surface uniformity and pore distribution was obtained for a current density of around 8 mA/cm2 using solutions with DMF. A correlation between reflectance measurements and pore size is presented. The porous-silicon samples were used as substrate for hydroxyapatite growth by sol-gel method. X-ray diffraction (XRD) and SEM were used to characterize the layers grown. It was found that the layer topography obtained on PS samples was characterized by the evidence of Hydroxyapatite in the inter-pore regions and over the surface.

Asunto(s)

Materiales Biocompatibles , Durapatita/química , Silicio/química , Microscopía Electrónica de Rastreo , Porosidad , Difracción de Rayos X

RESUMEN

Trimethylsilyl chloride is an efficient activating agent for azines in isocyanide-based reactions, which then proceed through a key insertion of the isocyanide into a N-Si bond. The reaction is initiated by N activation of the azine, followed by nucleophilic attack of an isocyanide in a Reissert-type process. Finally, a second equivalent of the same or a different isocyanide inserts into the N-Si bond leading to the final adduct. The use of distinct nucleophiles leads to a variety of α-substituted dihydroazines after a selective cascade process. Based on computational studies, a mechanistic hypothesis for the course of these reactions was proposed. The resulting products exhibit significant activity against Trypanosoma brucei and T. cruzi, featuring favorable drug-like properties and safety profiles.

Asunto(s)

Antiparasitarios/farmacología , Cianuros/química , Hidrazinas/química , Nitrógeno/química , Silicio/química , Trypanosoma cruzi/efectos de los fármacos , Antiparasitarios/síntesis química , Antiparasitarios/química , Estructura Molecular , Pruebas de Sensibilidad Parasitaria