Virus adsorbent systems based on Amazon holocellulose and nanomaterials.

The environment preservation has been an important motivation to find alternative, functional, and biodegradable materials to replace polluting petrochemicals. The production of nonbiodegradable face masks increased the concentration of microplastics in the environment, highlighting the need for sustainable alternatives, such as the use of local by-products to create efficient and eco-friendly filtering materials. Furthermore, the use of smart materials can reduce the risk of contagion and virus transmission, especially in the face of possible mutations. The development of novel materials is necessary to ensure less risk of contagion and virus transmission, as well as to preserve the environment. Taking these factors into account, 16 systems were developed with different combinations of precursor materials (holocellulose, polyaniline [ES-PANI], graphene oxide [GO], silver nanoparticles [AgNPs], and activated carbon [AC]). Adsorption tests of the spike protein showed that the systems containing GO and AC were the most efficient in the adsorption process. Similarly, plate tests conducted using the VSV-IN strain cultured in HepG2 cells showed that the system containing all phases showed the greatest reduction in viral titer method. In agreement, the biocompatibility tests showed that the compounds extracted from the systems showed low cytotoxicity or no significant cytotoxic effect in human fibroblasts. As a result, the adsorption tests of the spike protein, viral titration, and biocompatibility tests showed that systems labeled as I and J were the most efficient. In this context, the present research has significantly contributed to the technological development of antiviral systems, with improved properties and increased adsorption efficiency, reducing the viral titer and contributing efficiently to public health. In this way, these alternative materials could be employed in sensors and devices for filtering and sanitization, thus assisting in mitigating the transmission of viruses and bacteria. RESEARCH HIGHLIGHTS: Sixteen virus adsorbent systems were developed with different combinations of precursor materials (holocellulose, polyaniline (ES-PANI), graphene oxide (GO), silver nanoparticles (AgNPs), and activated carbon (AC)). The system that included all of the nanocomposites holocellulose, PANI, GO, AgNPs, and AC showed the greatest reduction in viral titration. The biocompatibility tests revealed that all systems caused only mild or moderate cytotoxicity toward human fibroblasts.

Temperature Dependence of the Electrical Properties of Na2Ti3O7/Na2Ti6O13/POMA Composites.

The temperature dependence of the electrical properties of composites formed by biphasic sodium titanate and poly(o-methoxyaniline) (Na2Ti3O7/Na2Ti6O13/POMA) with different concentrations of POMA (0%, 1%, 10%, 15%, 35% and 50%) in the ceramic matrix was determined from measurements of complex impedance. The structural details were studied by means of X-ray diffraction, confirming the formation of the Na2Ti3O7/Na2Ti6O13/POMA composites. The displacement of the (200) reflection from 2θ = 10.45° to 11.15° in the composites with 10 and 15% of POMA suggested the partial replacement of H+ for Na+ in the Na2Ti3O7 structure. The thermal properties were investigated by Thermogravimetry and Differential Thermal Analysis. The Thermogravimetry curves of the composites with POMA content of 1, 10 and 15% presented profiles similar to that of pure sodium titanate sample. The composites with 35 and 50% of POMA showed a process at temperatures around 60-70 °C, which was associated with water absorbed by the polymer. The analysis of the complex impedance spectroscopy measurements revealed that the electrical resistivity of the composites in the range from 0 to 35% increased by two orders of magnitude, with different values for each concentration. This positive temperature coefficient of resistivity was less noticeable in the composite with highest POMA mass content (50%). The rapid increase in resistivity caused an increase in the relaxation time calculated from the time domain. The electrical response of the 50% of POMA compound changes in relation to what was observed in the other compounds, which suggests that there is a saturation limit in the increase in resistivity with POMA content.

Treatment with isolated gold nanoparticles reverses brain damage caused by obesity.

In this study, we performed two experiments. In the first experiment, the objective was to link gold nanoparticles (GNPs) with sodium diclofenac and/or soy lecithin and to determine their concentration in tissues and their toxicity using hepatic and renal analyzes in mice to evaluate their safety as therapeutic agents in the subsequent treatment of obesity. In the second experiment, we evaluated the effect of GNPs on inflammatory and biochemical parameters in obese mice. In the first experiment, we synthesized and characterized 18 nm GNPs that were administered intraperitoneally in isolation or in association with sodium diclofenac and/or soy lecithin in mice once daily for 1 or 14 days. Twenty-four hours after the single or final administration, the animals were euthanized, following which the tissues were removed for evaluating the concentration of GNPs, and serum samples were collected for hepatic and renal analysis. Hepatic damage was evaluated based on the levels of alanine aminotransferase (ALT), whereas renal damage was evaluated based on creatinine levels. A higher concentration of GNPs was detected in the tissues upon administration for 14 days, and there were no signs of hepatic or renal damage. In the second experiment, the mice were used as animal models of obesity and were fed a high-fat diet (obese group) and control diet (control group). After eight weeks of high-fat diet administration, the mice were treated with saline or with GNPs (average size of 18 nm) at a concentration of 70 mg/L (70 mg/kg) once a day, for 14 days, for 10 weeks. Body weight and food intake were measured frequently. After the experiment ended, the animals were euthanized, serum samples were collected for glucose and lipid profile analysis, the mesenteric fat content was weighed, and the brains were removed for inflammatory and biochemical analysis. In obese mice, although GNP administration did not reduce body and mesenteric fat weight, it reduced food intake. The glucose levels were reversed upon administration of GNPs, whereas the lipid profile was not altered in any of the groups. GNPs exerted a beneficial effect on inflammation and oxidative stress parameters, without reverting mitochondrial dysfunction. Our results indicate that the intraperitoneal administration of GNPs for 14 days results in a significant GNP concentration in adipose tissues, which could be an interesting finding for the treatment of inflammation associated with obesity. Based on the efficacy of GNPs in reducing dietary intake, inflammation, and oxidative stress, they can be considered potential alternative agents for the treatment of obesity.

2-methoxy-isobutyl-isonitrile-conjugated gold nanoparticles improves redox and inflammatory profile in infarcted rats.

The tissue response to acute myocardial infarction (AMI) is key to avoiding heart complications due to inflammation, mitochondrial dysfunction, and oxidative stress. Antioxidant and anti-inflammatory agents can minimize the effects of AMI. This study investigated the role of 2-methoxy-isobutyl-isonitrile (MIBI)-associated gold nanoparticles (AuNP) on reperfusion injury after ischemia and its effect on cardiac remodeling in an experimental AMI model. Three-month-old Wistar rats were subjected to a temporary blockade of the anterior descending artery for 30 min followed by reperfusion after 24 h and 7 days by intraventricularly administering 0.4, 1.3, and 3 mg/kg AuNP-MIBI. The cardiac toxicity and renal and hepatic function levels were determined, and the infarct and peri-infarct regions were surgically removed for histopathology, analysis of inflammation from oxidative stress, and echocardiography. MIBI-conjugated AuNP promoted changes in oxidative stress and inflammation depending on the concentrations used, suggesting promising applicability for therapeutic purposes.

Effects of treatment with gold nanoparticles in a model of acute pulmonary inflammation induced by lipopolysaccharide.

The bacterial lipopolysaccharide (LPS) is a highly toxic molecule derived from the outer membrane of gram-negative bacteria. LPS endotoxin affects the lungs and is used as a model of acute pulmonary inflammation affecting the cellular morphology of the organ. Previously, gold nanoparticles (GNPs) have been shown to demonstrate anti-inflammatory and antioxidative activity in muscle and epithelial injury models. The objective of this study was to investigate the effect of the intraperitoneal treatment using GNPs on the inflammatory response and pulmonary oxidative stress induced by LPS. Wistar rats were divided into four groups (N = 10): Sham; Sham + GNPs 2.5 mg/kg; LPS; and LPS + GNPs 2.5 mg/kg. Treatment with LPS upregulated the levels of markers of cellular and hepatic damage (CK, LDH, AST, and alanine aminotransferase); however, the group treated with only GNPs exhibited no toxicity. Treatment with GNPs reversed LPS-induced changes with respect to total peritoneal leukocyte count and the pulmonary levels of pro-inflammatory cytokines (IFN-γ and IL-6). Histological analysis revealed that treatment with GNPs reversed the increase in alveolar septum thickness due to LPS-induced fibrosis. In addition, treatment with GNPs decreased production of oxidants (nitrite and DCFH), reduced oxidative damage (carbonyl and sulfhydryl), and downregulated activities of superoxide dismutase and catalase. Treatment with GNPs did not showed toxicity; however, it exhibited anti-inflammatory and antioxidative activity that reversed morphological alterations induced by LPS.

One-pot synthesis of gold nanoparticles embedded in polysaccharide-based hydrogel: Physical-chemical characterization and feasibility for large-scale production.

In this study, polysaccharide-based hydrogel wound dressings containing in situ synthesized gold nanoparticles (AuNPs) were prepared by using a simple, fast and green protocol. The prepared hydrogels were characterized with UV-vis and infrared spectroscopy (FT-IR), and dynamic light scattering (DLS). The rheological and swelling properties and the feasibility to scale-up the wound dressing production from the lamination of the prepared hydrogel on non-woven fabric were also investigated. UV-vis spectra confirmed the AuNPs synthesis and the DLS results exhibited an increase in the size of AuNPs with increasing the initial Au3+ concentration. The rheological analysis showed that the augmentation of the initial Au3+ concentration reduces the gel viscosity and gelling temperature. Besides, the FT-IR spectra revealed that the AuNPs hinder the intermolecular interactions between kappa-carrageenan (κCG) and locust bean gum (LBG). The feasibility of scale-up the wound dressing production from the prepared hydrogel was confirmed through the lamination tests.

Facile, green and scalable method to produce carrageenan-based hydrogel containing in situ synthesized AgNPs for application as wound dressing.

This manuscript was focused on introducing a facile, green and scalable method to produce kappa-carrageenan (κC) hydrogel membranes containing in situ synthesized silver nanoparticles (AgNPs). In a typical protocol, κC hydrogels were obtained by heating (sol phase), followed by cooling (gel phase) the polysaccharide solution, which enabled the simultaneous synthesis of AgNPs during the heating time. The as synthesized AgNPs were characterized spectrophotometrically, and by dynamic light scattering and transmission electron microscopy. The swelling properties at different pH and the antimicrobial activity of κC-AgNP hydrogel were investigated. AgNPs were mostly spherical in shape, crystalline in nature and measuring ca. 27nm in diameter. The in situ synthesis of AgNPs changed the swelling properties of κC hydrogel and also reduces its viscosity and gelling temperature. The AgNPs were continuously released from κC hydrogel for up to 48h in a concentration sufficient to prevent the bacterial growth as confirmed by antimicrobial tests. The simplicity involved in the AgNPs synthesis combined to the good spreadability of κC hydrogel makes this method suitable for scale-up to manufacturing quantities of wound dressing.

Effect of acute and long-term administration of gold nanoparticles on biochemical parameters in rat brain.

The present study investigated stress oxidative parameters and activities of enzymes of the energy metabolism in various brain structures. Rats were subjected to acute and long-term administration of gold nanoparticles (GNPs) with mean diameters of 10nm and 30nm. Adult (60days old) male Wistar rats received a single intraperitoneal injection (acute administration; 70µg·kg-1) or repeated injections once daily for 28days (long-term administration; 70µg·kg-1) of saline solution or GNPs (10nm or 30nm). Twenty-four hours after administration of the final dose, the animals were killed and the cerebral structures were isolated for enzyme analysis. In this study, we observed that the thiobarbituric acid-reactive species and carbonyl protein levels were decreased after acute administration of GNPs, whereas the superoxide dismutase activity was increased after acute and long-term of GNPs. The catalase activity was affected by the administration of GNPs. Furthermore, we have not found change in the citrate synthase activity. The succinate dehydrogenase, malate dehydrogenase, complexes I, II, II-III and IV, and creatine kinase activities were altered. These results indicate that inhibition energy metabolism can be caused by oxidative stress.

Safety protocol for the gold nanoparticles administration in rats.

Gold nanoparticles (GNPs) have antioxidant and anti-inflammatory effects. However, toxicity is still a concern; therefore, it is critical to study both the therapeutic and toxic properties of GNPs. In this study, we evaluated the effects of the intraperitoneal administration of GNPs (20nm, at a concentration of 2.5mg/L for 21days) every 24 or 48h on oxidative stress, antioxidant status, and electron chain transport (ETC) in the brain. Liver histology and blood marker analyses were conducted to establish a time routine of GNP administration. The concentrations of GNP in the brain and liver were similar. Hepatic and serum levels of cholesterol, triglycerides, and transaminases were not altered after the administration of GNP every 24 or 48h. The superoxide and nitric oxide levels were unchanged after administration of GNP. Dichlorodihydrofluorescein (DCFH) levels decreased after the administration of GNP every 48h compared with that in the saline group. Sulfhydryl and carbonyl levels, as well as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione (GSH) activities were not altered in the brain after administration of GNP in the two time periods studied. The GNP 48h group showed increased brain ETC activity. Compared to that in the saline group, the GNP 24h group showed marked parenchyma changes with cell necrosis and leukocyte infiltration. We therefore suggest that a concentration of 2.5mg/L of GNP administered every 48h has potential therapeutic benefits without toxicity.

Self-association of sodium deoxycholate with EHEC cellulose cooperatively induced by sodium dodecanoate.

Some aspects of ethyl (hydroxyethyl) cellulose (EHEC) aqueous behavior in the presence of ionic surfactants are described in the literature; however, most of the studies reported address moderately concentrated solutions. Few studies have been carried out in the dilute regime using mixtures of biosurfactants. The main purpose of this work is to investigate the interaction of EHEC in the dilute regime and to verify the mixture of two surfactants: sodium deoxycholate (NaDC) and sodium dodecanoate (SDoD). The parameters of the surfactant to polymer association processes such as the critical aggregation concentration (cac) and saturation of the polymer by surfactants (psp) were determined from the plots of surface tension and specific conductivity versus surfactant concentration in basic conditions. The cmc of NaDC-SDoD mixtures showed non-ideal behavior. However, EHEC added to mixtures of SDoD and NaDC acts as a stabilizer for the mixed aggregate during the association process.

Acute and chronic administration of gold nanoparticles cause DNA damage in the cerebral cortex of adult rats.

The use of gold nanoparticles is increasing in medicine; however, their toxic effects remain to be elucidated. Studies show that gold nanoparticles can cross the blood-brain barrier, as well as accumulate in the brain. Therefore, this study was undertaken to better understand the effects of gold nanoparticles on rat brains. DNA damage parameters were evaluated in the cerebral cortex of adult rats submitted to acute and chronic administration of gold nanoparticles of two different diameters: 10 and 30nm. During acute administration, adult rats received a single intraperitoneal injection of either gold nanoparticles or saline solution. During chronic administration, adult rats received a daily single injection for 28 days of the same gold nanoparticles or saline solution. Twenty-four hours after either single (acute) or last injection (chronic), the rats were euthanized by decapitation, their brains removed, and the cerebral cortices isolated for evaluation of DNA damage parameters. Our study showed that acute administration of gold nanoparticles in adult rats presented higher levels of damage frequency and damage index in their DNA compared to the control group. It was also observed that gold nanoparticles of 30nm presented higher levels of damage frequency and damage index in the DNA compared to the 10nm ones. When comparing the effects of chronic administration of gold nanoparticles of 10 and 30nm, we observed that occurred significant different index and frequency damage, comparing with control group. However, there is no difference between the 10 and 30nm groups in the levels of DNA damage for both parameters of the Comet assay. Results suggest that gold nanoparticles for both sizes cause DNA damage for chronic as well as acute treatments, although a higher damage was observed for the chronic one.

Effects of gold nanoparticles on endotoxin-induced uveitis in rats.

PURPOSE: This study evaluates the effects of the gold nanoparticle in endotoxin-induced uveitis in rats. METHODS: Adult male Wistar rats were divided into five groups: saline + saline, lipopolysaccharide (LPS) + saline, LPS + prednisolone, LPS + gold salt (GS) and LPS + gold nanoparticle (GNP). Two hours after LPS administration, prednisolone acetate 1%, GS, and GNP were topically applied to both eyes of rats and repeated every 6 hours for 24 hours. After 24 hours, rats were anesthetized and aqueous humor was sampled and the irides were removed. Aqueous humor TNF-α, myeloperoxidase activity were determined. Irides oxidative damage and content of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) were determined. RESULTS: The administration of LPS-induced eye inflammatory response characterized by an increase in aqueous humor TNF-α, myeloperoxidase, and by irides oxidative damage. All these parameters were decreased by the administration of GNP. Since the inflammatory response secondary to LPS administration depends, in part, to the activation of the TLR4-NF-κB pathway we demonstrated here that a potential mechanism to explain the GNP effects was the decrease on TLR4 content and NF-κB activation. CONCLUSIONS: These findings suggest that topical GNP decreases intraocular inflammation and oxidative damage by interfering in the TLR4-NF-κB pathway.

Pharmacological activity of ruthenium complexes trans-[RuCl(2)(L)4] (l = nicotinic or i-nicotinic acid) on anxiety and memory in rats.

Many biological properties have been attributed to ruthenium complex I (trans-[RuCl(2)(nic)(4)]) and ruthenium complex II (trans-[RuCl(2 )(i-nic)( 4)]) including nitric oxide synthase inhibition. In this study, we evaluated pharmacological effects of these complexes on anxiety and memory formation. Memory was evaluated with inhibitory avoidance and habituation to an open-field and anxiety was tested with elevated plus-maze. Adult male Wistar rats (250 to 350 g) received intraperitoneal injections of vehicle, ruthenium complex I (45.2, 90.4, or 180.7 mumol/kg), or ruthenium complex II (0.08, 4.5, or 13.6 mumol/kg) 30 min prior open-field training or elevated plus-maze test and 30 min or 0 h after training. No effects were observed in the anxiety parameters and habituation to an open-field. The ruthenium complexes impaired memory retention compared with vehicle group in the inhibitory avoidance, as when administrated 30 min prior as immediately after training. The memory impairment induced by ruthenium complexes may be due to their nitric oxide synthase inhibition capacity.