Eco-friendly Synthesis of Silver Nanoparticles and its Application in Hydrogen Photogeneration and Nanoplasmonic Biosensing.

Environmentally friendly methods for silver nanoparticles (AgNPs) synthesis without the use of hazardous chemicals have recently drawn attention. In this work, AgNPs have been synthesized by microwave irradiation using only honey solutions or aqueous fresh pink radish extracts. The concentrations of honey, radish extract, AgNO3 and pH were varied. AgNPs presented mean sizes between 7.0 and 12.8 nm and were stable up to 120 days. The AgNPs were employed as co-catalyst (TiO2 @AgNPs) to increase the hydrogen photogeneration under UV-vis and only visible light irradiation, when compared to pristine TiO2 NPs. The prepared photocatalyst also showed hydrogen generation under visible light. Additionally, AgNPs were used to assemble a nanoplasmonic biosensor for the biodetection of extremely low concentrations of streptavidin, owing to its specific binding to biotin. It is shown here that green AgNPs are versatile nanomaterials, thus being potential candidates for hydrogen photogeneration and biosensing applications.

Cytotoxic Effects Caused by Functionalized Carbon Nanotube in Murine Macrophages.

BACKGROUND/AIMS: The development of new nanomaterials has been growing in recent decades to bring benefits in several areas, especially carbon-based nanoparticles, which have unique physical-chemical properties and allow to take on several applications. Consequently, the use of new nanomaterials without previous toxicological studies raises concern about possible harmful health effects. The aim of this study was to investigate the cytotoxic profile of a new multi-walled carbon nanotube (MWCNT) functionalized with tetraethylenepentamine called OCNT-TEPA using in vitro assays in murine macrophage cells linage J774 A.1. METHODS: OCNT-TEPA was characterized by transmission electron microscopy (TEM) and high resolution TEM (HR-TEM), scanning electron microscopy (SEM), zeta potential and dynamic light scattering (DLS), and its cytotoxic effects were evaluated at 24 and 48 hours by cell viability assays (MTT and NR), morphology and cell recovery (optic microscopy and clonogenic assay), formation of reactive oxygen (ROS) and nitric oxide (NO) species, inflammatory profile (IL-6 and TNF cytokines), mitochondrial membrane potential analysis (MMP), activation of the caspase 3 pathway and cell death (flow cytometry). RESULTS: The data showed a significant decrease in cell viability, increased production of ROS and NO, alteration of mitochondrial membrane potential, increased levels of inflammatory cytokines, alteration of cell morphology, activation of the Caspase 3 pathway and consequently cell death, in the highest concentrations of OCNT-TEPA tested in the periods of 24 and 48 hours. CONCLUSION: The analyses showed that OCNT-TEPA has a dose-dependent cytotoxic profile, which may be harmful to murine macrophages (J774 A.1) and may represent a health risk.

Performance-optimized otoplasty.

OBJECTIVES: This study proposes a new surgical alternative for the most common deformity in the ears, the so-called "protruding/prominent ears", which is a condition that affects 5% of the Caucasian population (Goulart et al. in Rev Bras Cir Plast 26:602-607, 2011). This technique comes with the benefits of reduced surgical time, shallow learning curve, and a low revision rate. METHODS: We studied a total of 213 patients with an indication for otoplasty from January 2020 to January 2021. Women made up 65% of the study population, while men made up 35%, with an average age of 21 years, the youngest being 7 years of age. The technique presented here corrects all the deformities that cause protruding ears and can be performed together with other ear surgeries, such as surgical treatment of macrotia and lobuloplasty. All surgeries were performed in an outpatient setting under local anesthesia and sedation. RESULTS: All surgeries followed a performance-optimized protocol, with an average total surgical time of 45 min for a bilateral approach. Revision surgery was needed in 2% of cases, with the most frequent complaint being asymmetry in the upper third of the ears. The complication rate was approximately 7.5%, with 1 case of hematoma, 1 case of mild infection, 2 cases of altered ear sensitivity, 3 cases of keloid scar formation, 6 cases of asymmetry in the upper third of the ears, and 3 cases of irregularities or spikes in the antihelix cartilage. Patient satisfaction was measured using the McDowell/Wright Objectives and Outcome Index (McDowell in Plast Reconstr Surg 41:17-27). CONCLUSION: The proposed performance technique is a viable alternative to optimize the surgical time of otoplasty in an outpatient setting. This technique can be performed together with other corrective ear surgeries, has a shallow learning curve, and has a low revision rate. LEVEL IV: Evidence obtained from multiple time series with or without the intervention, such as case studies.

Analysis of cytotoxicity and genotoxicity in a short-term dependent manner induced by a new titanium dioxide nanoparticle in murine fibroblast cells.

The extensive use of titanium dioxide nanoparticles (TiO2 NPs) in cosmetics, food, personal care products, and industries brought concerns about their possible harmful effects. Nowadays it has become important to assess TiO2 NPs toxic effects as a way to understand their primary risks. In the cellular environment, after cell uptake, TiO2 NPs were described to induce reactive oxygen species (ROS) production, unbalance oxidative state, and activate apoptosis in several cell lines. Therefore, we aimed to evaluate the cytotoxicity and genotoxicity of a new TiO2 NP surface-functionalized with sodium carboxylic ligands in a murine fibroblast cell line (LA-9). TEM and DLS analyses were performed to define nanoparticle physicochemical characteristics. We evaluated the metabolic activity and LDH released after 24 h exposition to determine cytotoxic effects. Also, we evaluated DNA damage, intracellular reactive oxygen species (ROS) production, and apoptosis induction after 24 h exposure. The TiO2 NP impaired the cell membrane integrity at 1000 µg/mL, induced intracellular ROS production and late apoptosis at 24 h. The genotoxic effects were observed at all conditions tested at 24 h. Indeed, in fibroblasts exposed at 100 µg/mL was observed early apoptosis cells. The intracellular ROS content was increased in a dose-dependent manner. Thus, short-term exposure to TiO2 NP promoted cytotoxicity, genotoxicity and activated apoptosis pathways based on the potential role of oxygen species in the fibroblasts cell line.

Apoptosis and Oxidative Stress Triggered by Carbon Black Nanoparticle in the LA-9 Fibroblast.

BACKGROUND/AIMS: A new type of nanoparticle, called NP CB-EDA (Black Carbon modified with ethylenediamine), is commonly used in the oil industry. In the literature, few studies are found in biological models, making NP-EDA potential cytotoxicity in organisms unclear. As its large surface area is capable of interacting with the biological system, that interaction could lead to factors harmful to health. The objective of this study was to investigate the cytotoxic effect of NP CB-EDA on fibroblasts LA-9 at 24 and 48 hours, at different concentrations of the nanoparticle (1, 50, 250, 500 and 1000 µg/ml). METHODS: NP CB-EDA was characterized by TEM microscopy and its effect on cell viability (MTT method), cell morphology (optical microscopy), cell membrane (lactate dehydrogenase release - LDH), oxidative stress pathways (species levels reactive oxygen, ROS and nitrogen, NOS) and apoptosis/necrosis (flow cytometry) were evaluated. RESULTS: The results show that NP CB-EDA at concentrations of 500 and 1000 µg/ml form clusters. The nanoparticle can be absorbed by cells decreasing cell viability. There was damage to the cell membrane of fibroblasts LA 9, an increase in the production of ROS, NOS and pro-inflammatory interleukins TNF-α and IL-6; it was also observed an increase in % of cells in the state of apoptosis in the two periods analyzed, being this response more significant in 24 hours, and concentrations of 250, 500 and 1000 µg/ml presenting higher cytotoxicity. CONCLUSION: The data suggest that NP CB-EDA in fibroblasts LA9 presents cytotoxic potential, which is associated with oxidative stress and apoptosis.

Uniaxial and Coaxial Electrospinning for Tailoring Jussara Pulp Nanofibers.

Jussara pulp (Euterpe edulis Mart.) is rich in bioactive compounds known to be protective mediators against several diseases. In this context, nevertheless, anthocyanins, the most abundant natural pigment in jussara, are sensitive to temperature, pH, oxygen, and light conditions, leading to instability during food storage or digestion, and, thus jeopardizing the antioxidant proprieties retained by these flavonoids and limiting industrial application of the pulp. The production of nanostructures, from synthetic and natural polymers, containing natural matrices rich in bioactive compounds, has been widely studied, providing satisfactory results in the conservation and maintenance of the stability of these compounds. The current work aimed to compare uniaxial and coaxial electrospinning operation modes to produce core-shell jussara pulp nanofibers (NFs). Additionally, the parameters employed in the electrospinning processes were optimize using response surface methodology in an attempt to solve stability issues for the bioactive compounds. The best experimental conditions provided NFs with diameters ranging between 110.0 ± 47 and 121.1 ± 54 nm. Moreover, the coaxial setup improved jussara pulp NF formation, while further allowing greater integrity of NFs structures.

New Multi-Walled carbon nanotube of industrial interest induce cell death in murine fibroblast cells.

The search for new nanomaterials has brought to the multifactorial industry several opportunities for use and applications for existing materials. Carbon nanotubes (CNT), for example, present excellent properties which allow us to assume a series of applications, however there is concern in the industrial scope about possible adverse health effects related to constant exposure for inhalation or direct skin contact. Thus, using cell models is the fastest and safest way to assess the effects of a new material. The aim of this study was to investigate the cytotoxic profile in LA9 murine fibroblast lineage, of a new multi-walled carbon nanotube (MWCNT) that was functionalized with tetraethylenepentamine (TEPA) to obtain better physical-chemical characteristics for industrial use. The modifications presented in the CNT cause concern, as they can change its initial characteristics, making this nanomaterial harmful. HR-TEM, FE-SEM and zeta potential were used for the characterization. Cytotoxicity and cell proliferation tests, oxidative and nitrosative stress analyzes and inflammatory cytokine assay (TNF-α) were performed. The main findings demonstrated a reduction in cell viability, increased release of intracellular ROS, accompanied by an increase in TNF-α, indicating an important inflammatory profile. Confirmation of the data was performed by flow cytometry and ImageXpress with apoptosis/necrosis markers. These data provide initial evidence that OCNT-TEPA has a cytotoxic profile dependent on the concentration of LA9 fibroblasts, since there was an increase in free radicals, inflammation induction and cell death, suggesting that continuous exposure to this nanoparticle can cause damage to different tissues in the organism.

Microwave-Driven Hexagonal-to-Monoclinic Transition in BiPO4: An In-Depth Experimental Investigation and First-Principles Study.

Present theoretical and experimental work provides an in-depth understanding of the morphological, structural, electronic, and optical properties of hexagonal and monoclinic polymorphs of bismuth phosphate (BiPO4). Herein, we demonstrate how microwave irradiation induces the transformation of a hexagonal phase to a monoclinic phase in a short period of time and, thus, the photocatalytic performance of BiPO4. To complement and rationalize the experimental results, first-principles calculations have been performed within the framework of density functional theory. This was aimed at obtaining the geometric, energetic, and structural parameters as well as vibrational frequencies; further, the electronic properties (band structure diagram and density of states) of the bulk and corresponding surfaces of both the hexagonal and monoclinic phases of BiPO4 were also acquired. A detailed characterization of the low vibrational modes of both the hexagonal and monoclinic polymorphs is key to explaining the irreversible phase transformation from hexagonal to monoclinic. On the basis of the calculated values of the surface energies, a map of the available morphologies of both phases was obtained by using Wulff construction and compared to the observed scanning electron microscopy images. The BiPO4 crystals obtained after 16-32 min of microwave irradiation provided excellent photodegradation of Rhodamine B under visible-light irradiation. This enhancement was found to be related to the surface energy and the types of clusters formed on the exposed surfaces of the morphology. These findings provide details of the hexagonal-to-monoclinic phase transition in BiPO4 during microwave irradiation; further, the results will assist in the design of electronic devices with higher efficiency and reliability.

α-AgVO3 Decorated by Hydroxyapatite (Ca10(PO4)6(OH)2): Tuning Its Photoluminescence Emissions and Bactericidal Activity.

Defect-related luminescent materials have attracted interest because of their excellent optical properties and are considered as a less expensive and nontoxic alternative to commonly used lanthanide-based optical systems. These materials are fundamentally and technologically important for the next generation of full-color tunable light-emitting diodes as well as in the biomedical field. In this study, we report the preparation of α-silver vanadate (α-AgVO3, AV) decorated by hydroxyapatite (Ca10(PO4)6(OH)2, HA) with intense photoluminescence (PL) emissions at various HA/AV molar ratios (1:1-1:1/32) by a simple route based on chemical precipitation. The well-defined diffraction peaks observed by X-ray diffraction were all indexed to the monoclinic AV and hexagonal HA phases. Analysis of the results obtained by Fourier transform infrared spectroscopy reveals the presence of short-range structural order as deduced by the characteristic vibrational modes assigned to AV and HA systems. Characterization by scanning and transmission electron microscopies confirms the presence of AV and HA micro- and nanorods, respectively. UV-vis spectroscopy renders band gap energies of 5.80 eV for HA and in the range 2.59-2.65 eV for pure AV and HA/AV samples. The PL data reveal the presence of broad-band emission profiles, typical of defect-related optical centers in materials. Depending on the molar ratio, the emission can be completely tunable from the blue to red spectral regions; in addition, pure white color emission was obtained. On the basis of these results, we propose an order-disorder model induced by structural and interface defects to explain the PL emissions in the HA/AV system. Moreover, our results show that HA/AV composites have superior bactericidal activity against Staphylococcus aureus (methicillin-resistant and methicillin-susceptible) and can be used as a novel multifunctional material.

Laser-induced formation of bismuth nanoparticles.

In the current communication, the synthesis of metallic Bi nanoparticles with coexisting crystallographic structures (rhombohedral, monoclinic, and cubic) obtained via direct femtosecond laser irradiation of NaBiO3 is demonstrated for the first time. By exploring the use of high laser power values, it is revealed that the promoted laser-mediated reactions lead to the synthesis of coexisting phases in metal nanoparticles, which may be a widely occurring phenomenon in other materials under femtosecond laser irradiation, and a fundamental concern for laser-based nanofabrication.

Tuning the electronic properties of Zr UiO-66 through defect-functionalised multivariate modulation.

The multivariate modulation of Metal-Organic Frameworks is presented as a valuable tool to introduce multiple functional units into UiO-66 while increasing its porosity. This manuscript encloses a comprehensive study using p-functionalised benzoate -NO2, -SO3 and -SH modulators, rationalizing the defects introduced and their impact on properties.

Modulation of cell death mechanisms via α-Ag2WO4 morphology-dependent factors.

The cytotoxic of α-Ag2WO4 synthesized in different morphologies (cuboidal (AW-C), hexagonal rod-like (AW-HRL) and nanometric rod-like (AW-NRL) was analyzed to understand the impact of morphological modulation on the toxicity of 3 T3 cell lines in the dark and when photoactivated by visible light. Pathways of toxicity were examined, such as parameters and electrostatic interaction, uptake, ion release and ROS production. Cytotoxicity was observed for all samples after reaching concentrations exceeding 7.8 µg/mL. Uptake tests demonstrated that the samples were not internalized by cells, likely due to their negative surface charge. AW-NRL exhibited autophagy in the absence of light and during photoactivation, primarily attributed to its ability to generate singlet oxygen. Analyzing intercellular ROS and RNS production, AW-HRL induced an increase in NO through exposure to photo-generated hydroxyl radicals, while AW-NRL showed increases only at non-photoactivated concentrations and AW-C did not exhibit increases. Interestingly, in the dark, these cells showed a low propensity for apoptosis, with late apoptosis and necrosis being more pronounced. When photoactivated, this behavior changed, revealing predominantly apoptotic and late apoptotic cell death. There is a need for an understanding of how morphology can alter the biological properties of α-Ag2WO4 to predict and optimize its effects on cellular responses.

Efficient photoelectrochemical real textile wastewater detoxification using photoanodes of C3N4-BiVO4.

Photoelectrochemical systems utilizing solar energy have garnered significant attention for their sustainability in remediating contaminated water. This study focuses on advancing photoanode development through the utilization of carbon nitrides (C3N4) and bismuth vanadate (BiVO4), two promising semiconductor materials renowned for their efficient electron-hole pair separation leading to enhanced photocatalytic activity. Four distinct materials were synthesized and compared: BiVO4 over C3N4, C3N4 over BiVO4, and pristine BiVO4 and C3N4. Upon electrochemical analysis, the C3N4-BiVO4 heterostructure exhibited the highest photoelectrocatalytic charge transfer constant, mobility, and lifetime of charge carriers. Capitalizing on these exceptional properties, the composite was applied to remove organic matter real effluent from the textile industry. The photoelectrodegradation of the effluent demonstrated substantial removal of Total Organic Carbon (TOC) and the generation of low toxicity degradation products, accompanied by low energy consumption. The compelling results underscore the high potential of the synthesized C3N4-BiVO4 heterostructure for industrial applications, particularly in addressing environmental challenges associated with textile industry effluents.

Tracking of structural defects induced by Eu-doping in ß-Ag2MoO4: their influences on electrical properties.

In this study, several methods were employed to investigate the electrical characteristics of ß-Ag2MoO4 systems, both Eu-doped and undoped, synthesized using the microwave-assisted hydrothermal method. The focus extended to understanding how synthesis time influences material defects, with doping fixed at 1%. A systematic shift in the silver vacancy (VAg) concentration was observed within the doped ß-Ag2MoO4 system. Specifically, this study demonstrated that the incorporation of Eu3+ into polycrystalline ß-Ag2MoO4 initially increases the VAg concentration. However, as the synthesis time progresses, the VAg concentration decreases, resulting in alterations in the resulting electrical properties, arising from the intricate interplay between the number of grain boundaries and carrier density. By combining information obtained from photoluminescence, positron annihilation lifetime spectroscopy, and impedance spectroscopy, a comprehensive conduction mechanism was formulated, shedding light on both doped and undoped ß-Ag2MoO4 systems.

Striking the balance: Unveiling the interplay between photocatalytic efficiency and toxicity of La-incorporated Ag3PO4.

Persistent molecules, such as pesticides, herbicides, and pharmaceuticals, pose significant threats to both the environment and human health. Advancements in developing efficient photocatalysts for degrading these substances can play a fundamental role in remediating contaminated environments, thereby enhancing safety for all forms of life. This study investigates the enhancement of photocatalytic efficiency achieved by incorporating La3+ into Ag3PO4, using the co-precipitation method in an aqueous medium. These materials were utilized in the photocatalytic degradation of Rhodamine B (RhB) and Ciprofloxacin (CIP) under visible light irradiation, with monitoring conducted through high-performance liquid chromatography (HPLC). The synthesized materials exhibited improved stability and photodegradation levels for RhB. Particularly noteworthy was the 2% La3+-incorporated sample (APL2), which achieved a 32.6% mineralization of CIP, nearly three times higher than pure Ag3PO4. Toxicological analysis of the residue from CIP photodegradation using the microalga Raphidocelis subcapitata revealed high toxicity due to the leaching of Ag + ions from the catalyst. This underscores the necessity for cautious wastewater disposal after using the photocatalyst. The toxicity of the APL2 photocatalysts was thoroughly assessed through comprehensive toxicological tests involving embryo development in Danio rerio, revealing its potential to induce death and malformations in zebrafish embryos, even at low concentrations. This emphasizes the importance of meticulous management. Essentially, this study adeptly delineated a thorough toxicological profile intricately intertwined with the photocatalytic efficacy of newly developed catalysts and the resultant waste produced, prompting deliberations on the disposal of degraded materials post-exposure to photocatalysts.

Effects of ZnWO4 nanoparticles on growth, photosynthesis, and biochemical parameters of the green microalga Raphidocelis subcapitata.

Nanoparticles have applications in many sectors in the society. ZnWO4 nanoparticles (ZnWO4-NPs) have potential in the fabrication of sensors, lasers, and batteries, and in environmental remediation. Thus, these NPs may reach aquatic ecosystems. However, we still do not know their effects on aquatic biota and, to our knowledge, this is the first study that evaluates the toxicity of ZnWO4-NPs in a eukaryotic organism. We evaluated the toxicity of ZnWO4-NPs on the green microalga Raphidocelis subcapitata for 96 h, in terms of growth, cell parameters, photosynthesis, and biochemical analysis. Results show that most of Zn was presented in its particulate form, with low amounts of Zn2+, resulting in toxicity at higher levels. The growth was affected from 8.4 mg L-1, with 96h-IC50 of 23.34 mg L-1. The chlorophyll a (Chl a) content increased at 30.2 mg L-1, while the fluorescence of Chl a (FL3-H) decreased at 15.2 mg L-1. We observed increased ROS levels at 44.4 mg L-1. Regarding photosynthesis, the NPs affected the oxygen evolving complex (OEC) and the efficiency of the photosystem II at 22.9 mg L-1. At 44.4 mg L-1 the qP decreased, indicating closure of reaction centers, probably affecting carbon assimilation, which explains the decay of carbohydrates. There was a decrease of qN (non-regulated energy dissipation, not used in photosynthesis), NPQ (regulated energy dissipation) and Y(NPQ) (regulated energy dissipation via heat), indicating damage to the photoprotection system; and an increase in Y(NO), which is the non-regulated energy dissipation via heat and fluorescence. The results showed that ZnWO4-NPs can affect the growth and physiological and biochemical parameters of the chlorophycean R. subcapitata. Microalgae are the base of aquatic food chains, the toxicity of emerging contaminants on microalgae can affect entire ecosystems. Therefore, our study can provide some help for better protection of aquatic ecosystems.

Biocompatibility and inflammatory response of silver tungstate, silver molybdate, and silver vanadate microcrystals.

Silver tungstate (α-Ag2WO4), silver molybdate (ß-Ag2MoO4), and silver vanadate (α-AgVO3) microcrystals have shown interesting antimicrobial properties. However, their biocompatibility is not yet fully understood. Cytotoxicity and the inflammatory response of silver-containing microcrystals were analyzed in THP-1 and THP-1 differentiated as macrophage-like cells, with the alamarBlue™ assay, flow cytometry, confocal microscopy, and ELISA. The present investigation also evaluated redox signaling and the production of cytokines (TNFα, IL-1ß, IL-6, and IL-8) and matrix metalloproteinases (MMP-8 and -9). The results showed that α-AgVO3 (3.9 µg/mL) did not affect cell viability (p > 0.05). α-Ag2WO4 (7.81 µg/mL), ß-Ag2MoO4 (15.62 µg/mL), and α-AgVO3 (15.62 µg/mL) slightly decreased cell viability (p ≤ 0.003). All silver-containing microcrystals induced the production of O2 - and this effect was mitigated by Reactive Oxygen Species (ROS) scavenger and N-acetylcysteine (NAC). TNFα, IL-6 and IL-1ß were not detected in THP-1 cells, while their production was either lower (p ≤ 0.0321) or similar to the control group (p ≥ 0.1048) for macrophage-like cells. The production of IL-8 by both cellular phenotypes was similar to the control group (p ≥ 0.3570). The release of MMP-8 was not detected in any condition in THP-1 cells. Although MMP-9 was released by THP-1 cells exposed to α-AgVO3 (3.9 µg/mL), no significant difference was found with control (p = 0.7). Regarding macrophage-like cells, the release of MMP-8 and -9 decreased in the presence of all microcrystals (p ≤ 0.010). Overall, the present work shows a promising biocompatibility profile of, α-Ag2WO4, ß-Ag2MoO4, and α-AgVO3 microcrystals.

Study of biological properties of gold nanoparticles: Low toxicity, no proliferative activity, no ability to induce cell gene expression and no antiviral activity.

Gold nanoparticles (AuNPs) are a fundamental building block of many applications across nanotechnology as they have excellent biosafety which make them promising for a broad range of biomedical applications. Here we explore their in vivo toxicity, cytotoxicity and proliferative capacity in human keratinocyte HaCaT cells, their ability to induce gene expression and their antiviral properties against a surrogate of SARS-CoV-2. These nanoparticles were characterized by transmission electron microscopy, dynamic light scattering and zeta potential. The results showed that these AuNPs with sizes ranging from 10 to 60 nm are non-toxic in vivo at any concentration up to 800 µg/mL. However, AuNP cytotoxicity in human HaCaT cells is time-dependent, so that concentrations of up to 300 µg/mL did not show any in vitro toxic effect at 3, 12 and 24 h, although higher concentrations were found to have some significant toxic activity, especially at 24 h. No significant proliferative activity was observed when using low AuNP concentrations (10, 20 and 40 µg/mL), while the AuNP antiviral tests indicated low or insignificant antiviral activity. Surprisingly, none of the 13 analyzed genes had their expressions modified after 24 h's exposure to AuNPs. Therefore, the results show that AuNPs are highly stable inactive materials and thus very promising for biomedical and clinical applications demanding this type of materials.

Unraveling the Intrinsic Biocidal Activity of the SiO2-Ag Composite against SARS-CoV-2: A Joint Experimental and Theoretical Study.

The COVID-19 pandemic has emerged as an unprecedented global healthcare emergency, demanding the urgent development of effective materials to inactivate the SARS-CoV-2 virus. This research was planned to disclose the remarkable biocidal activity of SiO2-Ag composites incorporated into low-density polyethylene. For this purpose, a joint experimental and theoretical [based on first-principles calculations at the density functional theory (DFT) level] study is performed. Biological assays showed that this material eliminatesStaphylococcus aureusand SARS-CoV-2 virus in just 2 min. Here, we investigate a previously unexplored process that we postulate may occur along the O2 and H2O adsorption and activation processes of pure and defective SiO2-Ag surfaces for the generation of reactive oxygen species (ROS). The obtained results help us to predict the nature of ROS: superoxide anion radicals, •O2-, hydroxyl radicals, •OH, and hydroperoxyl radicals, •HO2, that destroy and degrade the structure of the SARS-COV-2 virus. This is consistent with the DFT studies, where the energetic, electronic, and magnetic properties of the intermediates show a feasible formation of ROS. Present findings are expected to provide new insights into the relationship among the structure, property, and biocidal activity of semiconductor/metal SiO2-Ag composites.

Carbon Black CB-EDA Nanoparticles in Macrophages: Changes in the Oxidative Stress Pathway and in Apoptosis Signaling.

The influence of black carbon nanoparticles on J774.A1 murine cells was investigated with the objective of exploring the cytotoxicity of black carbon functionalized with ethylenediamine CB-EDA. The results showed that CB-EDA has a cytotoxic profile for J774.A1 macrophages in a time- and dose-dependent manner. When phagocytosed by the macrophage, CB-EDA triggers a mechanism that leads to apoptosis. In this process, there is an increase in oxidative stress pathways due to the activation of nitric oxide and then ROS. This causes an imbalance in redox function and a disruption of membrane integrity that occurs due to high levels of LDH, in addition to favoring the release of the pro-inflammatory cytokines IL-6, IL-12, and tumor necrosis factor (TNF) in an attempt to modulate the cell. However, these stimuli are not sufficient to repair the cell and the level of mitochondrial integrity is affected, causing a decrease in cell viability. This mechanism may be correlated with the activation of the caspasse-3 pathway, which, when compromised, cleaves and induces cells death via apoptosis, either through early or late apoptosis. In view of this, the potential for cell damage was investigated by analyzing the oxidative and inflammatory profile in the macrophage lineage J774.A1 and identifying potential mechanisms and metabolic pathways connected to these processes when cells were exposed to NP CB-EDA for both 24 h and 48 h.