RESUMEN

Developing heterojunction photocatalyst with well-matched interfaces and multiple charge transfer paths is vital to boost carrier separation efficiency for photocatalytic antibiotics removal, but still remains a great challenge. In present work, a new strategy of chloride anion intercalation in Bi2O3 via one-pot hydrothermal process is proposed. The as-prepared Ta-BiOCl/Bi24O31Cl10 (TBB) heterojunctions are featured with Ta-Bi24O31Cl10 and Ta-BiOCl lined shoulder-by-shouleder via semi-coherent interfaces. In this TBB heterojunctions, the well-matched semi-coherent interfaces and shoulder-by-shoulder structures provide fast electron transfer and multiple transfer paths, respectively, leading to enhanced visible light response and improved photogenerated charge separation. Meanwhile, a type-II heterojunction for photocharge separation has been obtained, in which photogenerated electrons are drove from the CB (conduction band) of Ta-Bi24O31Cl10 to the both of bilateral empty CB of Ta-BiOCl and gathered on the CB of Ta-BiOCl, while the photogenerated holes are left on the VB (valence band) of Ta-Bi24O31Cl10, effectively hindering the recombination of photogenerated electron-hole pairs. Furthermore, the separated electrons can effectively activate dissolved oxygen for the generation of reactive oxygen species (·O2-). Such TBB heterojunctions exhibit remarkably superior photocatalytic degradation activity for tetracycline hydrochloride (TCH) solution to Bi2O3, Ta-BiOCl and Ta-Bi24O31Cl10. This work not only proposes a Ta-BiOCl/Bi24O31Cl10 shoulder-by-shoulder micro-ribbon architectures with semi-coherent interfaces and successive type-II heterojunction for highly efficient photocatalytic activity, but offers a new insight into the design of highly efficient heterojunction through phase-structure synergistic transformation strategy.

Asunto(s)

Antibacterianos , Bismuto , Contaminantes Químicos del Agua , Bismuto/química , Antibacterianos/química , Contaminantes Químicos del Agua/química , Catálisis , Procesos Fotoquímicos

RESUMEN

Carbon dioxide electroreduction is a green technology for artificial carbon sequestration, which is being delayed from industrialization due to the lack of efficient catalysts at high current conditions. Herein, the Bi2O3 nanoflakes were uniformly grown on a defective porous carbon (PC). This self-assembling Bi2O3/PC catalyst was applied to drive CO2 electroreduction at 1.0 A, 1.5 A and 2.0 A while the Faradaic efficiency of formate reaches 91.50 %, 86.30 % and 84.22 %, respectively. Density functional theory calculations revealed the intrinsic defect of carbon is able to give electron to Bi through O bridge, which increased the electron aggregation of Bi and lowered the generation energy barrier of *OCHO intermediate. Additionally, the unique 3D network of staggered Bi2O3 enhances the CO2 adsorption and favors the electron transportation. By integrating all above advantages into a solid electrolyte-type cell, we are able to produce pure formic acid in a rate of 15.48 mmol h-1 at ampere current.

RESUMEN

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@ß-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@ß-Bi2O3 achieved a degradation efficiency of 74.0% for 5 ppm toluene after 5 h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.

Asunto(s)

Tolueno , Tolueno/química , Catálisis , Compuestos Orgánicos Volátiles/química , Bismuto/química , Fotólisis

RESUMEN

The electrochemical CO2 reduction reaction (ECO2RR) is a promising strategy for converting CO2 into high-value chemical products. However, the synthesis of effective and stable electrocatalysts capable of transforming CO2 into a specified product remains a huge challenge. Herein, we report a template-regulated strategy for the preparation of a Bi2O3-derived nanosheet catalyst with abundant porosity to achieve the expectantly efficient CO2-to-formate conversion. The resultant porous bismuth nanosheet (p-Bi) not only exhibited marked Faradaic efficiency of formate (FEformate), beyond 91% in a broad potential range from -0.75 to -1.1 V in the H-type cell, but also demonstrated an appreciable FEformate of 94% at a high current density of 262 mA cm-2 in the commercially important gas diffusion cell. State-of-the-art X-ray absorption near edge structure spectroscopy (XANES) and theoretical calculation unraveled the distinct formate production performance of the p-Bi catalyst, which was cocontributed by its smaller size, plentiful porous structure, and stronger Bi-O bond, thus accelerating the absorption of CO2 and promoting the subsequent formation of intermediates. This work provides an avenue to fabricate bismuth-based catalysts with high planar and porous morphologies for a broad portfolio of applications.

RESUMEN

Recently, it was shown that the nanocrystallization of Bi2O3 glasses with the addition of SiO2 and Al2O3 leads to the stabilization of the δ-like Bi2O3 phase at least down to room temperature, which is significantly below its stability range in bulk form. In this research, we investigated the properties of bismuthate glasses synthesized with various glass-forming agents such as SiO2, GeO2, B2O3, and Al2O3. It was demonstrated that vitrification of all these systems is possible using a standard melt quenching route. Furthermore, we investigated the crystallization processes in pristine glasses upon increasing the temperature and the thermal stability of arising phases using thermal analysis and high-temperature XRD in situ experiments. It was shown that it is possible to stabilize crystallites' isostructures with δ-Bi2O3 embedded in a residual glassy matrix down to room temperature. The temperature range of the appearance of the δ-like phase strongly depended on the nominal composition of the glasses. We postulate that the confinement effect depends on the local properties of the residual glassy matrix and its ability to introduce sufficient force to stretch the structure of the δ-like Bi2O3 phase in the nanocrystallites.

RESUMEN

We prepare bismuth oxide-reduced graphene oxide (Bi2O3-rGO) composite anode using a one-step chemical precipitation/reduction method. Under a reducing atmosphere, oxygen atoms on the surface of Bi2O3 are gradually removed and neighboring oxygen atoms migrate to the surface, leaving oxygen vacancies. Defective Bi2O3 enhances the number of active sites, providing additional pseudocapacitive performance. The transition metal oxide-based Bi2O3 acts as an anode, providing capacitive performance that far exceeds that of conventional carbon materials. Moreover, the introduction of rGO forms a conductive network for Bi2O3, improving capacitive contribution and ion diffusion capabilities for the electrode. The Bi2O3-rGO-100 (GO added at 100 mg) exhibits a high specific capacitance of 1053F/g at 1 A/g, significantly higher than that of Bi2O3 (866F/g). The Bi2O3-rGO-100 anode and Ni3Co2-rGO cathode are assembled into a battery-type supercapacitor. The coin-cell device achieves an energy density of 88.2 Wh kg-1 at a power density of 850 W kg-1. The Ni3Co2-rGO//Bi2O3-rGO-100 pouch-cell device demonstrates an extremely low Rct of 0.77 Ω. At a power density of 850 W kg-1, the energy density reaches 118.5 Wh kg-1, and remains 67.4 Wh kg-1 at 8500 W kg-1.

RESUMEN

Electrochemical carbon dioxide reduction reaction (ECO2RR) is a promising approach to synthesize fuels and value-added chemical feedstocks while reducing atmospheric CO2 levels. Here, high surface area cerium and sulfur-doped hierarchical bismuth oxide nanosheets (Ce@S-Bi2O3) are develpoed by a solvothermal method. The resulting Ce@S-Bi2O3 electrocatalyst shows a maximum formate Faradaic efficiency (FE) of 92.5% and a current density of 42.09 mA cm-2 at -1.16 V versus RHE using a traditional H-cell system. Furthermore, using a three-chamber gas diffusion electrode (GDE) reactor, a maximum formate FE of 85% is achieved in a wide range of applied potentials (-0.86 to -1.36 V vs RHE) using Ce@S-Bi2O3. The density functional theory (DFT) results show that doping of Ce and S in Bi2O3 enhances formate production by weakening the OH* and H* species. Moreover, DFT calculations reveal that *OCHO is a dominant pathway on Ce@S-Bi2O3 that leads to efficient formate production. This study opens up new avenues for designing metal and element-doped electrocatalysts to improve the catalytic activity and selectivity for ECO2RR.

RESUMEN

Bismuth (Bi)-based computed tomography (CT) imaging contrast agents (CAs) hold significant promise for diagnosing gastrointestinal diseases due to their cost-effectiveness, heightened sensitivity, and commendable biocompatibility. Nevertheless, substantial challenges persist in achieving an easy synthesis process, remarkable water solubility, and effective targeting ability for the potential clinical transformation of Bi-based CAs. Herein, we show Bi drug-inspired ultra-small dextran coated bismuth oxide nanoparticles (Bi2O3-Dex NPs) for targeted CT imaging of inflammatory bowel disease (IBD). Bi2O3-Dex NPs are synthesized through a simple alkaline precipitation reaction using bismuth salts and dextran as the template. The Bi2O3-Dex NPs exhibit ultra-small size (3.4 nm), exceptional water solubility (over 200 mg mL-1), high Bi content (19.75 %), excellent biocompatibility and demonstrate higher X-ray attenuation capacity compared to clinical iohexol. Bi2O3-Dex NPs not only enable clear visualization of the GI tract outline and intestinal loop structures in CT imaging but also specifically target and accumulate at the inflammatory site in colitis mice after oral administration, facilitating a precise diagnosis and enabling targeted CT imaging of IBD. Our study introduces a novel and clinically promising strategy for synthesizing high-performance Bi2O3-Dex NPs for diagnosing gastrointestinal diseases.

Asunto(s)

Bismuto , Medios de Contraste , Dextranos , Enfermedades Inflamatorias del Intestino , Tomografía Computarizada por Rayos X , Bismuto/química , Animales , Dextranos/química , Tomografía Computarizada por Rayos X/métodos , Enfermedades Inflamatorias del Intestino/diagnóstico por imagen , Ratones , Medios de Contraste/química , Nanopartículas/química , Ratones Endogámicos C57BL

RESUMEN

The rational design of Z-scheme heterojunction hybrid photocatalysts is considered a promising way to achieve high photocatalytic activity. In this study, a dual Z-scheme heterojunction with bismuth sulfide (Bi2S3) nanorods and bismuth oxide (Bi2O3) nanoparticles anchored Sulfur-doped carbon nitride (S-CN) nanotubes (Bi2S3/S-CN/Bi2O3) is designed and fabricated through the ordinal metal ion adsorption, pyrolysis, and sulfidation processes using supramolecular rods as precursor. Compared with pristine Bi2S3, Bi2O3, and CN, the dual Z-scheme tube-shaped Bi2S3/S-CN/Bi2O3 catalyst exhibited a significantly improved photocatalytic activity in amine oxidation. The optimized Bi2S3/S-CN/Bi2O3 nanostructure exhibits a 97.6 % benzylamine conversion and 99.4 % imine selectivity within 4 h under simulated solar light irradiation. The excellent activity of Bi2S3/S-CN/Bi2O3 nanotubes can be attributed to the characteristic hollow defect band structure and efficient charge separation and transfer achieved by the dual Z-scheme charge transfer mechanism, which was systematically studied using electron spin resonance spectroscopy, Kelvin probe force microscope, and other techniques. The optimized dual Z-scheme heterojunction hybrid photocatalyst maintains the high oxidizing ability of Bi2S3 and Bi2O3 and the excellent reducing ability of CN, thereby significantly enhancing the photocatalytic activity. This research provides a facile and feasible synthesis strategy for designing dual Z-scheme heterojunctions with defect band structure to improve the photocatalytic activity.

RESUMEN

Bismuth vanadate (BiVO4) exhibits large absorption efficiency for hard X-rays, which endows it with a robust capacity to attenuate X-ray radiation across a broad energy range. The anisotropic properties of BiVO4 allow for the manipulation of their physical and chemical characteristics through crystallographic orientation and exposed facets. In this study, the issue of heavy recombination caused by sluggish electron transport in BiVO4 is successfully addressed by enhancing the abundance of the (040) crystal face ratio using a Co2+ crystal face exposure agent. The facet-dependent modifications exhibit excellent and balanced intrinsic charge transport properties, and finely optimize both the sensitivity and detection limit of BiVO4 X-ray detectors. As a result, ultra-stable BiVO4 metal oxide X-ray detectors demonstrate a high sensitivity of 3164 µC Gyair -1 cm-2 and a low detection limit of 20.76 nGyair s-1 under 110 kVp hard X-rays, establishing a new benchmark for X-ray detectors based on polycrystalline Bi-halides and metal oxides. These findings highlight the significance of crystal orientation in optimizing materials for X-ray detection, setting a new sensitivity record for X-ray detectors based on polycrystalline Bi-halides and metal oxides, which paves the way for the development of advanced, low-dose, and highly stable imaging systems specifically for hard X-rays.

RESUMEN

Nanotechnology-based diagnostic, and therapeutic approaches revolutionized the field of cancer detection, and treatment, offering tremendous potential for cost-effective interventions in the early stages of disease. This research synthesized bismuth oxide (Bi2O3) nanoparticles (NPs) that were modified with polycyclodextrin (PCD), and functionalized with glucose (Glu) to load curcumin (CUR) for CT imaging and chemo-radiotherapy applications in Breast Cancer. The prepared Bi2O3@PCD-CUR-Glu NPs underwent comprehensive characterization, encompassing various aspects, including cell migration, cytotoxicity, cellular uptake, blood compatibility, reactive oxygen species (ROS) generation ability, real-time PCR analysis, in-vivo safety assessment, in-vivo anti-tumor efficacy, as well as in-vitro CT contrast and X-ray RT enhancement evaluation. CT scan was conducted before and after (1 and 3 h) intravenous injection of Bi2O3@PCD-CUR-Glu NPs. Through the use of coupled plasma optical emission spectrometry (ICP-OES) analysis, the final prepared nanoparticle distribution in the Bab/c mice was assessed. The spherical NPs that were ultimately synthesized and had a diameter of around 80 nm demonstrated exceptional toxicity towards the SKBr-3 breast cancer cell line. The cell viability was at its lowest level after 48 h of exposure to a radiation dose of 2 Gy at a concentration of 100 µg/mL. The combined treatment involving using Bi2O3@PCD-CUR-Glu NPs along with X-ray radiation showed a substantial increase in the generation of ROS, specifically a remarkable 420 % growth. Gene expression analysis indicated that the expression levels of P53, and BAX pro-apoptotic genes were significantly increased. The in-vitro CT imaging analysis conducted unequivocally demonstrated the notable superiority of NPs over Omnipaque in terms of X-ray absorption capacity, a staggering 1.52-fold increase at 80 kVp. The resultsdemonstrated that the targeted Bi2O3@PCD-CUR-Glu NPs could enhance the visibility of a small mice tumor that is detectable by computed tomography and made visible through X-ray attenuation. Results suggested that Bi2O3@PCD-CUR-Glu NPs, integrated with CT imaging and chemo-radiotherapy, have great potential as a versatile theranostic system for clinical application.

Asunto(s)

Bismuto , Neoplasias de la Mama , Curcumina , Ratones Endogámicos BALB C , Nanopartículas , Tomografía Computarizada por Rayos X , beta-Ciclodextrinas , Curcumina/administración & dosificación , Curcumina/química , Curcumina/farmacología , Animales , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Neoplasias de la Mama/terapia , Femenino , Humanos , Línea Celular Tumoral , Tomografía Computarizada por Rayos X/métodos , beta-Ciclodextrinas/química , Bismuto/química , Bismuto/administración & dosificación , Nanopartículas/química , Ratones , Especies Reactivas de Oxígeno/metabolismo , Quimioradioterapia/métodos , Supervivencia Celular/efectos de los fármacos , Antineoplásicos/administración & dosificación , Antineoplásicos/farmacología , Antineoplásicos/química

RESUMEN

Liquid crystalline nanoparticles (LCNPs) have gained much attention in cancer nanomedicines due to their unique features such as high surface area, storage stability, and sustained-release profile. In the current study, a novel LCNP for co-encapsulation of Bi2O3 and hydrophilic doxorubicin (DOX) was fabricated and functionalized with folic acid (FA) to achieve efficient tumor targeting toward CT-scan imaging and chemotherapy of melanoma in vitro and in vivo. LCNPs Bi2O3 NPs were prepared using glycerol monooleate-pluronic F-127 (GMO/PF127/water). Firstly, GMO/water were homogenized to prepare LC gel. Then, the stabilizer aqueous solution (PF127/Bi2O3/DOX) was added to the prepared LC gel and homogenized using homogenization and ultrasonication. The formulated NPs exhibited superior stability with encapsulation efficiency. High cytotoxicity and cellular internalization of the FA-Bi2O3-DOX-NPs were observed in comparison with Bi2O3-DOX-NPs and the free DOX in folate-receptor (FR) overexpressing cells (B16F10) in vitro. Moreover, ideal tumor suppression with increased survival rate were observed in tumorized mice treated with FA-Bi2O3-DOX-NPs compared to those treated with non-targeted one. On the other hand, the CT-imaging ability of the Bi2O3-DOX-NPs was tested inB16F10 tumor-bearing mice. The obtained data indicated a high potential of the developed targeted theranostic FA-Bi2O3-DOX-NPs for diagnostics and treatment of melanoma.

Asunto(s)

Bismuto , Melanoma , Nanopartículas , Animales , Ratones , Sistemas de Liberación de Medicamentos/métodos , Medicina de Precisión , Ácido Fólico/química , Doxorrubicina , Nanopartículas/química , Agua , Línea Celular Tumoral

RESUMEN

In this study, a simple novel hybrid mesoporous nanomaterial derived from a metal-organic framework (ZIF-8) and chitosan, which were coated on green bismuth oxide, has been successfully synthesized, characterized, and applied to investigate its dapsone loading-releasing capability in the aqueous media. This suggested nanocomposite showed promise for drug loading from water b using hydrogen bonds, pi-pi, and electrostatic interactions. Structural and morphological analyses were performed on the proposed green synthesized nanocomposite through scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, and thermogravimetric analysis. Various influencing parameters, including pH, nanocomposite dose, and contact time, were investigated to optimize the dapsone loading process. Utilizing the non-linear optimization methodology, the results show that dapsone-loading efficiency was >85 % for 50 mg.L-1 of dapsone drug. The optimum parameters for achieving maximal loading of dapsone drug were pH = 6.8, hybrid mesosphere dose = 2.6 mg.mL-1, and time = 53 min. Based on the release investigations, the dapsone-loaded nanocomposite was put into phosphate buffer saline, at pH = 7.4 and T = 37 °C, with a maximum efficiency of 93.9 after 24 h.

Asunto(s)

Quitosano , Nanocompuestos , Quitosano/química , Agua/química , Dapsona , Microscopía Electrónica de Rastreo , Nanocompuestos/química , Espectroscopía Infrarroja por Transformada de Fourier

RESUMEN

Bismuth is a catalyst material that selectively produces formate during the electrochemical reduction of CO2. While different synthesis strategies have been employed to create electrocatalysts with better performance, the restructuring of bismuth precatalysts during the reaction has also been previously reported. The mechanism behind the change has, however, remained unclear. Here, we show that Bi2O3 nanoparticles supported on Vulcan carbon intrinsically transform into stellated nanosheet aggregates upon exposure to an electrolyte. Liquid cell transmission electron microscopy observations first revealed the gradual restructuring of the nanoparticles into nanosheets in the presence of 0.1 M KHCO3 without an applied potential. Our experiments also associated the restructuring with solubility of bismuth in the electrolyte. While the consequent agglomerates were stable under moderate negative potentials (-0.3 VRHE), they dissolved over time at larger negative potentials (-0.4 and -0.5 VRHE). Operando Raman spectra collected during the reaction showed that under an applied potential, the oxide particles reduced to metallic bismuth, thereby confirming the metal as the working phase for producing formate. These results inform us about the working morphology of these electrocatalysts and their formation and degradation mechanisms.

RESUMEN

Non-uniform, non-spherical bismuth oxide deposited on titanium vanadium oxide (3%-BVT1) was successfully synthesized via co-precipitation method and assessed for visible light degradation of aqueous diclofenac. The synthesized photocatalysts were characterized using X-ray diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Up to 80.7% diclofenac degradation was observed with a significant increment in reaction rate compared to commercially available Degussa P25 (kapp = 0.0013 → 0.0083 min-1) achieved within 3 h treatment time under optimized parameters of diclofenac concentration (10 mg L-1), catalyst loading (0.1 g L-1), and pH (5). The enhanced photocatalysis could be due to electron-hole separation and contribution of powerful oxidative species •OH > O2•- > h+ > > e-. The recyclability experiments indicate that 3%-BVT1 retained its efficiency up to 74.1% over five reaction cycles. Gas chromatography-mass spectrometry analysis indicated the formation of several transformation products during the degradation pathway. The studies of interfering ions depicted mild interference by sulfates, while interference by phosphates and nitrates was negligible during photocatalytic process, i.e., 70, 78.01, and 78.43% for the selected concentrations of 50, 25, and 40 mg L-1 as per their maximum concentrations detected in the natural wastewaters. Thus, 3%-BVT1 is a potential versatile candidate to treat various organic pollutants including pharmaceuticals.

Asunto(s)

Diclofenaco , Vanadio , Titanio/química , Luz , Bismuto/química , Agua , Catálisis

RESUMEN

BACKGROUND: Selective accumulation of photosensitizers into cancerous cells is one of the most important factors affecting photodynamic therapy (PDT) efficacy. 5-aminolevulinic acid (5-ALA) is the precursor of a strong photosensitizer, protoporphyrin-IX; but it has poor permeability into the cells. Folate receptors are overexpressed on the surface of many tumor cells. In the present study, folic acid (FA) and 5-ALA conjugated bismuth oxide nanoparticles were synthesized; and used in PDT, radiotherapy (RT), and concurrent PDT & RT against nasopharyngeal carcinoma (KB cell line). METHODS: The KB cells were incubated with the synthesized nanoparticles (NPs) for 2 h; then illuminated using a custom-made LED lamp at the light dose of 26 J/cm2. Irradiation of the cells was carried out using X-ray 6 MV (2 Gy); and synergistic effect of the simultaneous RT and PDT treatments was evaluated using fractional product values. Efficacy of the treatments was determined using MTT and Caspase-3 enzyme activity assays. RESULTS: Targeting of folic acid receptors enables the selective endocytosis of the conjugated NPs. RT results in the presence of Bi2O3 NPs showed a significant radiosensitizer potential of these NPs. Fractional product values of 1.49±0.05, 1.36±0.06, and 1.05±0.06 obtained in the presence of FA-5-ALA conjugated NPs, 5-ALA conjugated NPs, and in the absence of the NPs, respectively. Therefore, simultaneous RT and PDT in the presence of these conjugated NPs is superior to RT in the presence of the NPs. CONCLUSION: Simultaneous PDT and RT in the presence of FA-5-ALA conjugated bismuth oxide NPs can be introduced as a promising therapeutic approach in controlling KB cancer cells.

Asunto(s)

Ácido Aminolevulínico , Bismuto , Ácido Fólico , Fotoquimioterapia , Fármacos Fotosensibilizantes , Fotoquimioterapia/métodos , Bismuto/farmacología , Humanos , Fármacos Fotosensibilizantes/farmacología , Ácido Aminolevulínico/farmacología , Células KB , Ácido Fólico/química , Nanopartículas/química , Supervivencia Celular/efectos de los fármacos , Neoplasias Nasofaríngeas/tratamiento farmacológico , Neoplasias Nasofaríngeas/radioterapia , Línea Celular Tumoral

RESUMEN

This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances.

RESUMEN

BACKGROUND: Nanotechnology has emerged as a transformative realm of exploration across diverse scientific domains. A particular focus lies on metal oxide nanoparticles, which boast distinctive physicochemical attributes on the nanoscale. Of note, green synthesis has emerged as a promising avenue, leveraging plant extracts as both reduction and capping agents. This approach offers environmentally friendly and cost-effective avenues for generating monodispersed nanoparticles with precise morphologies. METHODS: In this investigation, we embarked on the synthesis of Bismuth oxide nanoparticles, both in their pure form and doped with silver (Ag) and copper (Cu). This synthesis harnessed the potential of Biebersteinia multifida extract as a versatile reducing agent. To comprehensively characterize the synthesized nanoparticles, a suite of analytical techniques was employed, including energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, and Raman spectroscopy. RESULTS: The synthesized nanoparticles underwent a rigorous assessment. Their antibacterial attributes were probed, revealing a pronounced enhancement in antibiofilm activity against Pseudomonas aeruginosa and Staphylococcus aureus bacteria upon metal nanoparticle doping. Furthermore, their potential for combating cancer was scrutinized, with the nanoparticles exhibiting selective cytotoxicity towards cancer cells, U87, compared to normal 3T3 cells. Notably, among the doped nanoparticles, Cu-doped variants demonstrated the highest potency, further underscoring their promising potential. CONCLUSION: In conclusion, the present study underscores the efficacy of green synthesized Bismuth oxide nanoparticles, particularly those doped with Ag and Cu, in augmenting antibacterial efficacy, bolstering biofilm inhibition, and manifesting selective cytotoxicity against cancer cells. These findings portend a promising trajectory for these nanoparticles in the spheres of biomedicine and therapeutics. As we look ahead, a deeper elucidation of their mechanistic underpinnings and in vivo investigations are essential to fully unlock their potential for forthcoming biomedical applications.

Asunto(s)

Antiinfecciosos , Antineoplásicos , Nanopartículas del Metal , Animales , Ratones , Espectroscopía Infrarroja por Transformada de Fourier , Antiinfecciosos/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Nanopartículas del Metal/química , Óxidos , Extractos Vegetales/química , Pruebas de Sensibilidad Microbiana , Difracción de Rayos X

RESUMEN

Bismuth oxides were synthesized from bismuth carbonate using the sol-gel method. Studies have described the formation of Bi2O3, as a precursor of HNO3 dissolution, and intermediate oxides, such as BixOy when using H2SO4 and H3PO4. The average size of the crystallite calculated from Scherrer's formula ranged from 9 to 19 nm, according to X-ray diffraction. The FTIR analysis showed the presence of specific Bi2O3 bands when using HNO3 and of crystalline phases of "bismuth oxide sulphate" when using H2SO4 and "bismuth phosphate" when using H3PO4. The TG curves showed major mass losses and specific thermal effects, delimited in four temperature zones for materials synthesized with HNO3 (with loss of mass between 24% and 50%) and H2SO4 (with loss of mass between 45% and 76%), and in three temperature zones for materials synthesized with H3PO4 (with loss of mass between 13% and 43%). Further, the thermal stability indicates that materials have been improved by the addition of a polymer or polymer and carbon. Confocal laser scanning microscopy showed decreased roughness in the series, [BixOy]N > [BixOy-6% PVA]N > [BixOy-C-6% PVA]N, and increased roughness for materials [BixOy]S, [BixOy-6% PVA]S, [BixOy-C-6% PVA]S, [BixOy]P, [BixOy-6% PVA]P and [BixOy-C-6% PVA]P. The morphological analysis (electronic scanning microscopy) of the synthesized materials showed a wide variety of forms: overlapping nanoplates ([BixOy]N or [BixOy]S), clusters of angular forms ([BixOy-6% PVA]N), pillars ([BixOy-6% PVA]S-Au), needle particles ([BixOy-Au], [BixOy-6% PVA]S-Au, [BixOy-C-6% PVA]S-Au), spherical particles ([BixOy-C-6% PVA]P-Pt), 2D plates ([BixOy]P-Pt) and 3D nanometric plates ([BixOy-C-6% PVA]S-Au). For materials obtained in the first synthesis stage, antimicrobial activity increased in the series [BixOy]N > [BixOy]S > [BixOy]P. For materials synthesized in the second synthesis stage, when polymer (polyvinyl alcohol, PVA) was added, maximum antimicrobial activity, regardless of the microbial species tested, was present in the material [BixOy-6% PVA]S. For the materials synthesized in the third stage, to which graphite and 6% PVA were added, the best antimicrobial activity was in the material [BixOy-C-6% PVA]P. Materials synthesized and doped with metal ions (gold or platinum) showed significant antimicrobial activity for the tested microbial species.

Asunto(s)

Bismuto , Nanoestructuras , Bismuto/farmacología , Oro , Platino (Metal) , Óxidos/farmacología , Polímeros

RESUMEN

CuBi2 O4 has recently emerged as a promising photocathode for photo-electrochemical (PEC) water splitting. However, its fast degradation under operation currently poses a limit to its application. Here, we report a novel method to study operando the semiconductor-electrolyte interface during PEC operation by surface-sensitive high-energy X-ray scattering. We find that a fast decrease in the generated photocurrents correlates directly with the formation of a metallic Bi phase. We further show that the slower formation of metallic Cu, as well as the dissolution of the electrode in contact with the electrolyte, further affect the CuBi2 O4 activity and morphology. Our study provides a comprehensive picture of the degradation mechanisms affecting CuBi2 O4 electrodes under operation and poses the methodological basis to investigate the photocorrosion processes affecting a wide range of PEC materials.