A simple, novel, cost-effective and highly sensitive spectrofluorimetric method was developed for estimation of the nasal decongestant oxymetazoline (OMZ) whether per se or in its pharmaceutical preparations using colloidal silver nanoparticles (AgNPs). The method is based on the high catalytic potential activity of AgNPs on the fluorescence intensity of OMZ leading to 12-fold increase in its fluorescence intensity. The response was linear over the range of 20.0 to 700.0 ng/mL with lower detection limit of 5.0 ng/mL and limit of quantification of 14.0 ng/mL. The proposed method was applied to the assay of commercial nasal drops, nasal spray and synthetic aqueous humor. Interference likely to be encountered from co-administered drugs was studied. The developed method was optimized and validated as per International Council of Harmonization (ICH). An explanation for the drug-AgNPs interaction was proposed.

The redox of silver on the surface of Ag nanoparticles (AgNPs) has received extensive attention because of its significant impact on the biological, physical and chemical properties of AgNPs and their applications. Here we demonstrate that the surface redox reaction of AgNPs in colloids may be investigated by the second harmonic generation (SHG) and two-photon luminescence (TPL) emission from the AgNPs. It was revealed that the oxidation of silver on the surface of AgNPs was accelerated upon femtosecond laser excitation, accompanied by a decrease in the SHG and TPL emissions from the AgNPs. The photon-induced reduction of oxidized silver on AgNPs and the formation of surface defects were also revealed by the changes in the SHG and TPL emissions. Size and morphology changes have not been detected by dynamic light scattering and TEM measurements. The changes in the UV-vis extinction spectra were also very weak compared with previous reports. However, the occurrence of redox reactions on the Ag surface upon femtosecond laser irradiation has been confirmed by multiple control experiments. This work demonstrates that SHG and TPL can sensitively probe the subtle structural change on the surface of AgNPs.

In response to the nowadays battle against SARS-CoV-2, we designed a new class of high performant filter media suitable to advance the facemask technology and provide new efficient widespread solutions against virus propagation. By means of the electrospinning technology we developed filter media based on polyvinyl alcohol (PVA) nanofibers doped with AgNPs combining three main performance requirements: high air filtration efficiency to capture nanometer-size particles, low airflow resistance essential to ensure breathability and antimicrobial activity to inactivate aerosolized microorganisms. PVA/AgNPs electrospun nanofibers were produced by electrospinning the dispersion of colloidal silver into the PVA water solution. A widespread physicochemical characterization was addressed to the Ag colloidal suspension. The key functional performances of the electrospun nanofibers were proven by water stability, antibacterial activity, and filtration efficiency and pressure drop measurements performed under conditions representative of facemasks. We assessed a total bacterial depletion associated to a filtering efficiency towards nano-aerosolized particles of 97.7% higher than required by the EN149 standard and a pressure drop in line with FFP1 and FFP2 masks, even at the highest filtration velocity. Such results pave the way to the application of PVA/AgNPs electrospun nanofibers in facemasks as advanced filtering media for protecting against airborne microorganisms.

Along with the progress of nanoscience and nanotechnology came the means to synthesize nanometric scale materials. While changing their physical and chemical properties, they implicitly changed their application area. The aim of this paper was the synthesis of colloidal silver nanoparticles (Ag-NPs by ultrasonic disruption), using soluble starch as a reducing agent and further as a stabilizing agent for produced Ag-NPs. In this context, an important parameter for Ag-NPs preparation is the pH, which can determine the particle size and stability. The physical-chemical behavior of the synthesized Ag-NPs (shape, size, dispersion, electric charge) is strongly influenced by the pH value (experiment being conducted for pH values in the range between 8 and 13). The presence of a peak located at 412 nm into the UV-VIS spectra demonstrates the presence of silver nano-spheres into the produced material. In UV/VIS spectra, we observed a specific peak for yellow silver nano-spheres located at 412 nm. Samples characterization was performed by scanning electron microscopy, SEM, energy-dispersive X-ray spectroscopy, EDX, Fourier-transform infrared spectroscopy, and FT-IR. For all Ag-NP samples, we determined the zeta and observed that the Ag-NP particles obtained at higher pH and have better stability. Due to the intrinsic therapeutic properties and broad antimicrobial spectrum, silver nanoparticles have opened new horizons and new approaches for the control of different types of infections and wound healing abilities. In this context, the present study also aims to confirm the antimicrobial effect of prepared Ag-NPs against several bacterial strains (indicator and clinically isolated strains). In this way, it was confirmed that the antimicrobial activity of synthesized Ag-NPs was good against Staphylococcus aureus (ATCC 25923 and S. aureus MSSA) and Escherichia coli (ATTC 25922 and clinically isolated strain). Based on this observation, we conclude that the prepared Ag-NPs can represent an alternative or auxiliary material used for controlling important nosocomial pathogens. The fungal reference strain Candida albicans was more sensitive at Ag-NPs actions (zone of inhibition = 20 mm) compared with the clinically isolated strain (zone of inhibition = 10 mm), which emphasizes the greater resistance of fungal strains at antimicrobial agent's action.

The ligands anchored to the surface of metal nanocrystals play an important role in controlling their colloidal synthesis for a broad spectrum of applications, but it remains a daunting challenge to investigate the ligand-surface and ligand-solvent interactions at the molecular level. Here, we report the use of surface-enhanced Raman scattering (SERS) to extract structural information about the binding of poly(vinylpyrrolidone) (PVP) to Ag nanocubes as well as its conformational changes in response to solvent quality. When a PVP chain binds to the surface of a Ag nanocube through some of its carbonyl groups, the segments between adjacent binding sites are expelled into the solvent as loops. As a result, the carbonyl peak (νC═O) resolved in the SERS spectrum includes the contributions from those anchored to the surface and those residing on the loops, with their frequencies located at νC═O(Ag) and νC═O(free), respectively. While νC═O(Ag) remains at a fixed frequency due to the coordination between the carbonyl groups with Ag surface, the spectral position of νC═O(free) is dependent on the solvent. As the strength of hydrogen bonding between PVP and solvent increases, the peak position of νC═O(free) shifts toward lower frequencies. When exposed to bad and good solvents in an alternating manner, the PVP loops undergo conformational changes between collapsed and extended states, altering the separation between the free carbonyl groups and the Ag surface and thereby the intensity of the νC═O peak.

In order to overcome the limitations of current endodontic sealers, especially against resistant bacteria, recent developments in the field of nanotechnology have proved the necessity to reconsider the composition and physico-chemical properties of classical sealers. Nanoparticles with their unique features in terms of small size and high specific surface area, are the best choice for incorporation of antiseptic agents and effective delivery. The aim of our study is to prepare a novel platform for antibacterial drug delivery in dental adhesive systems used in endodontics. For this purpose, multi-walled carbon nanotubes (MWCNTs) encapsulating chlorhexidine (CHX) and colloidal silver nanoparticles (AgNPs) were prepared and incorporated into commercial sealer and investigated in terms of bonding performance to dentin and effectiveness against E. faecalis, S. aureus and Candida albicans, which are responsible for the majority of the failures in endodontic treatments. In this context, the challenges related to the long-term biological effects of CHX/AgNPs loaded MWCNTs are discussed.

The pH-stimuli release behavior of nanoformulations may enhance the success rate of chemotherapeutic drugs in cancers by site-specific delivery of drugs to cancer tissues. The aim of the present study was to prepare chitosan (CS) nanoparticles (NPs) with previously synthesized folic acid (FA) capped silver nanoparticles (AgNPs) loaded with the anti-cancer drug gemcitabine (GEM) (FA-GEM-AgNPs). The CS-FA-GEM-AgNPs (CS-NPs) were characterized with dynamic light scattering (DLS), transmission electron microscopy (TEM), energy dispersive x-ray analysis (EDAX), selected area electron diffraction (SAED), and differential scanning calorimetric (DSC) analyses. The in-vitro drug release of GEM was evaluated in media of different pH. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was carried out to determine the cytotoxic effects of the prepared nanoformulations in media with various pH. The time- and pH-dependent apoptotic cell death induced by CS-NPs with MDA-MB-453 human breast cancer cell line was observed using acridine orange (AO)/ethidium bromide (EtBr) staining. The pharmacokinetic parameters were studied with high-performance liquid chromatography (HPLC) and atomic absorption spectroscopy (AAS). Two batches of CS-NPs formulations were prepared, one with AgNPs of particle size 143 nm and the other with 244 nm. The particle size for CS-NPs-I (FA-GEM-AgNPs-143 nm) and CS-NPs-II (FA-GEM-AgNPs-244 nm) was found to be 425 and 545 nm, respectively. The zeta potential was found to be 36.1 and 37.5 mV for CS-NPs-I and CS-NPs-II, respectively. CS-NPs-I and CS-NPs-II showed a polydispersity index (PDI) of 0.240 and 0.261, respectively. A TEM study confirmed the spherical nature of the NPs. The nanoformulations exerted pH-dependant effect against MDA-MB-453 cells with relatively higher cytotoxicity at the lower pH than at higher pH levels. The pharmacokinetic profile and tissue distribution of CS-NPs in rats exerted drug release in a pH-dependent manner with enhanced excretion of Ag+. An optimized nanoformulation for pH-stimuli responsive release of GEM was successfully developed for future therapeutic exploration.

In this study, we aimed to develop a technique for colloidal silver nanoparticle (AgNP) modification in order to increase their stability in aqueous suspensions. For this purpose, 40-nm spherical AgNPs were modified by the addition of either human albumin or Tween-80 (Polysorbate-80). After detailed characterization of their physicochemical properties, the hemolytic activity of the nonmodified and modified AgNPs was investigated, as well as their cytotoxicity and antimicrobial effects. Both albumin- and Tween-80-coated AgNPs demonstrated excellent stability in 0.9% sodium chloride solution (>12 months) compared to nonmodified AgNPs, characterized by their rapid precipitation. Hemolytic activity of nonmodified and albumin-coated AgNPs was found to be minimal, while Tween-80-modified AgNPs produced significant hemolysis after 1, 2, and 24 h of incubation. In addition, both native and Tween-80-covered AgNPs showed dose-dependent cytotoxic effects on human adipose-tissue-derived mesenchymal stem cells. The albumin-coated AgNPs showed minimal cytotoxicity. The antimicrobial effects of native and albumin-coated AgNPs against S. aureus, K. pneumonia, P. aeruginosa, Corynebacterium spp., and Acinetobacter spp. were statistically significant. We conclude that albumin coating of AgNPs significantly contributes to improve stability, reduce cytotoxicity, and confers potent antimicrobial action.

The ability of bacteria to develop resistance to antibiotics is threatening one of the pillars of modern medicine. It was recently understood that bacteria can develop resistance even to silver nanoparticles by starting to produce flagellin, a protein which induces their aggregation and deactivation. This study shows that silver covalently bound to cyanographene (GCN/Ag) kills silver-nanoparticle-resistant bacteria at concentrations 30 times lower than silver nanoparticles, a challenge which has been so far unmet. Tested also against multidrug resistant strains, the antibacterial activity of GCN/Ag is systematically found as potent as that of free ionic silver or 10 nm colloidal silver nanoparticles. Owing to the strong and multiple dative bonds between the nitrile groups of cyanographene and silver, as theory and experiments confirm, there is marginal silver ion leaching, even after six months of storage, and thus very high cytocompatibility to human cells. Molecular dynamics simulations suggest strong interaction of GCN/Ag with the bacterial membrane, and as corroborated by experiments, the antibacterial activity does not rely on the release of silver nanoparticles or ions. Endowed with these properties, GCN/Ag shows that rigid supports selectively and densely functionalized with potent silver-binding ligands, such as cyanographene, may open new avenues against microbial resistance.

Sludge generated in wastewater treatment facilities is an integral part for the introduction of silver nanoparticles (AgNPs) to the terrestrial environment, which would cause some adverse ecosystem responses. The understanding of silver release process from the sludge is important to evaluate their risks. In this study, the amount and speciation of the released silver were investigated by taking the sludge generated by wastewater coagulation with AgNPs added (denoted as sludgeC-AgNPs) an example, and kinetic analysis and density functional theory (DFT) calculations were first used to explore the controlling steps and pathways about the silver release. The results showed that sludgeC-AgNPs could release the dissolved silver and the colloidal silver. Beside Cl-, Ca2+ in the leaching solution could enhance the silver release of sludgeC-AgNPs, especially for the colloidal silver. The released colloidal silver restricted in size from 40 nm to 100 nm with irregular shape. Although the oxidative dissolution of Ag0 was the origin of the silver release pathways from the sludgeC-AgNPs, the silver diffusion was the controlling step due to the spontaneous binding between silver and the hydrolysates of polyaluminium chloride in sludgeC-AgNPs. However, Ca2+ in the leaching solution could occupy the binding site of silver on sludgeC-AgNPs, which would increase the diffusion rate of silver over the oxidative rate of Ag0. With this condition, the controlling step of silver release from sludgeC-AgNPs turned to the oxidative dissolution of Ag0. Our findings are important to assess the fate of AgNPs in wastewater treatment as well as sludge applications.

We have synthesized anthracene and metal@anthracene core-shell nanoparticles to combine radiation (RT) and photodynamic (PDT) therapies. Synthesis of anthracene nanoparticles in the presence of colloidal silver or gold reduced the nanoparticles hydrodynamic radius, caused core-shell nanostructures to grow, and led to plasmon-enhanced fluorescence. Singlet oxygen (1O2) generation was investigated by electron spin resonance (ESR) and fluorescence spectroscopies. In the presence of a porphyrin, anthracene nanoparticles and the core-shell nanoparticles acted as energy mediators and increased 1O2 generation under exposure to light, as evidenced by the ESR results. Fluorescence suppression experiments showed that the core-shell nanoparticles captured 1O2 at rates higher than anthracene nanoparticles, suggesting that overall production of 1O2 (1O2 captured by spin-trap + 1O2 captured by surface anthracene molecules) was higher for the core-shell nanoparticles. Moreover, the Ag@anthracene nanoparticles stood out as a new and more sensitive fluorescent probe for 1O2. During irradiation with X-rays, both anthracene and Ag@anthracene nanoparticles trapped 1O2; subsequently, they afforded sustained release of the trapped 1O2 for up 12 days after irradiation. This could be an interesting strategy to extend the radiation therapy treatment after the irradiation sessions. Furthermore, the presence of the metallic nanoparticle in the core of the core-shell nanostructure increased interaction with X-rays, raising the radiation dose around the nanoparticle. Therefore, metal@anthracene nanostructures may allow combination of cancer treatments by different approaches depending on the adopted nanoparticle configuration.

Following access into the cell, colloidal silver nanoparticles exhibit generalized cytotoxic properties, thus appear as omnipotent microbicidal, but not suitable for systemic use unless are free of toxic effects on host cells. The AgNP-Serum-18 when prepared from silver nitrate, using dextrose as reducing and group-matched homologous serum as a stabilizing agent, selective endocytosis, and oxidative stress-dependent bio-functional damages to the host are mostly eliminated. For their bio-mimicking outer coat, there is the least possibility of internalization into host cells or liberation of excess oxidants in circulation following interaction with erythrocytes or vascular endothelial cells. The presence of infection-specific antibodies in the serum can make such nano-conjugates more selective. A potent antimicrobial action and a wide margin of safety for mammalian cells in comparison with very similar PVA-capped silver nanoparticles have been demonstrated by the in-vitro challenge of such nanoparticles on different microbes, human liver cell-line, and in-vivo study on mice model. This may open up wide-range therapeutic prospects of colloidal nanoparticles.

The involvement of heterogeneous solid/liquid reactions in growing colloidal nanoparticles makes it challenging to quantitatively understand the fundamental steps that determine nanoparticles' growth kinetics. A global optimization protocol relying on simulated annealing fitting and the LSW growth model is developed to analyze the evolution data of colloidal silver nanoparticles synthesized from a microwave-assisted polyol reduction reaction. Fitting all data points of the entire growth process determines with high fidelity the diffusion coefficient of precursor species and the heterogeneous reduction reaction rate parameters on growing silver nanoparticles, which represent the principal functions to determine the growth kinetics of colloidal nanoparticles. The availability of quantitative results is critical to understanding the fundamentals of heterogeneous solid/liquid reactions, such as identifying reactive species and reaction activation energy barriers.

The application of green synthesis in nanotechnology is growing day by day. It's a safe and eco-friendly alternative to conventional methods. The current research aimed to study raw royal jelly's potential in the green synthesis of silver nanoparticles and their antibacterial activity. Royal jelly served as a reducing and oxidizing agent in the green synthesis technology of colloidal silver nanoparticles. The UV-Vis maximum absorption at ~ 430 nm and fluorescence emission peaks at ~ 487 nm confirmed the presence of Ag NPs. Morphology and structural properties of Ag NPs and the effect of ultrasound studies revealed: (i) the formation of polydispersed and spherical particles with different sizes; (ii) size reduction and homogeneity increase by ultrasound treatment. Antibacterial activity of different concentrations of green synthesized Ag NPs has been assessed on Gram-negative S. typhimurium and Gram-positive S. aureus, revealing higher sensitivity on Gram-negative bacteria.

Bodies have continuous reticular networks, comprising collagens, elastin, glycosaminoglycans, and other extracellular matrix components, through all tissues and organs. Fibrous coverings of nerves and blood vessels create structural continuity beyond organ boundaries. We recently validated fluid flow through human fibrous tissues, though whether these interstitial spaces are continuous through the body or discontinuous, confined within individual organs, remains unclear. Here we show evidence for continuity of interstitial spaces using two approaches. Non-biological particles (tattoo pigment, colloidal silver) were tracked within colon and skin interstitial spaces and into adjacent fascia. Hyaluronic acid, a macromolecular component of interstitial spaces, was also visualized. Both techniques demonstrate interstitial continuity within and between organs including within perineurium and vascular adventitia traversing organs and the spaces between them. We suggest that there is a body-wide network of fluid-filled interstitial spaces that has significant implications for molecular signaling, cell trafficking, and the spread of malignant and infectious disease.

Silver nanoparticles (AgNPs) are an environmental contaminant of emerging concern. Ionic and colloidal silver has long been used for its antimicrobial properties, but with the development of engineered AgNPs, these are increasingly incorporated in the manufacture of nano-enhanced products. AgNPs are released into the environment from manufacturing plants and they can be shed from products during use and after disposal. This can lead to chronic low-level environmental exposure in animals. Unlike traditional forms of silver, the unique physical properties of AgNPs allow them to bypass biological barriers and enter tissues, like the brain, where they can bioaccumulate. Thus, it is important to understand if low-level AgNPs induce physiological changes in brain cells. Previously we found that 1.0 μg/mL AgNP exposure resulted in disruption of f-actin organization and neurite collapse in cultured differentiating adult neural stem cells, and that interaction with β-catenin signaling was involved. Here, we report that AgNP exposure may interact with pAkt signaling irreversibly or indirectly to disrupt cytoskeleton and inhibit neurite extension. Furthermore, the MAPK/ERK signaling pathway is not a target for AgNP-mediated dysregulation. Environmental exposure to low-level AgNPs therefore appears to target specific cellular mechanisms to alter brain cell physiology. Understanding these underlying mechanisms is important for decisions regulating the use and disposal of manufactured AgNPs.

The emergence of antibiotic resistant bacteria requires for the development of new antimicrobial compounds one of which colloidal silver (CS) having strong bactericidal properties and being the most promising inorganic nanoparticles for the treatment of bacterial infectious diseases. However, their production can be slow and cumbersome. Here, we used Corymbia maculata aqueous leaf extract as a reducing agent to synthesize CS in a single 15-minute process. CS was physico-chemically characterized for shape, size, zeta potential and stability. The Minimal Inhibitory Concentration (MIC) and Minimum Biofilm Eradication Concentration (MBEC) of CS against planktonic and biofilm forms of methicillin-resistant Staphylococcus aureus (MRSA, n = 5), Pseudomonas aeruginosa (n = 5), Haemophilus influenzae (n = 5) and Streptococcus pneumoniae (n = 3) chronic rhinosinusitis clinical isolates were investigated using the microdilution method and resazurin assay, respectively. The in vitro cytotoxicity on bronchial epithelial cells (Nuli-1) was analyzed by the crystal violet proliferation assay. The safety and efficacy of CS was evaluated in an in vivo infection model in Caenorhabditis elegans. CS was spherical in shape with a diameter of between 11-16 nm (TEM analysis) in dried form and 40 nm (NanoSight) in colloidal form and was stable at room temperature and 4 °C for one year. Average MIC and MBEC values varied between 11 and 44 ppm for MRSA, H. influenzae and S. pneumoniae and between 0.2 and 3 ppm for P. aeruginosa. CS was not toxic to Nuli-1 cells or C. elegans at concentrations of 44 ppm and reduced the Colony Forming Units counts by 96.9 % and 99.6 % in C. elegans for MRSA and P. aeruginosa, respectively. In conclusion, a novel, green synthesis of stable CS is demonstrated with good safety and efficacy profiles, particularly against P. aeruginosa in planktonic and biofilm forms. These CS have potential applications against clinical infections, including in the context of CRS.

Colloidal CdS sensitized nano-ZnO/chitosan (CdS@n-ZnO/CS) hydrogel was prepared and characterized extensively by XRD, SEM-EDS, TEM, UV-Vis DRS, FT-IR and TGA. The photocatalytic activity of CdS@n-ZnO/CS was evaluated with the photodegradation of congo red (CR) as an organic pollutant under solar light irradiation. The influences of initial dye concentration, catalyst dosage, recycling runs, and radical scavenger on decolorization of CR by CdS@n-ZnO/CS were investigated. 95% of CR was removed in just 1 min for 5.0 mg L-1 and 94.34% of CR was removed in 30 min for 100 mg L-1. CdS@n-ZnO/CS exhibited an excellent and ultra-fast performance toward CR removal under solar light due to the synergistic effect of adsorption by chitosan and photocatalysis by ZnO and CdS in CdS@n-ZnO/CS hydrogel. Radical trapping control experiments indicated that h+ and O2- played the major role for CR decolorization. The high performance of CdS@n-ZnO/CS hydrogel was also demonstrated under natural solar light irradiation, suggesting that CdS@n-ZnO/CS hydrogel could be used in practical wastewater treatment.

The properties of materials at the nanoscale open up new methodologies for engineering prospective materials usable in high-end applications. The preparation of composite materials with a high content of an active component on their surface is one of the current challenges of materials engineering. This concept significantly increases the efficiency of heterogeneous processes moderated by the active component, typically in biological applications, catalysis, or drug delivery. Here we introduce a general approach, based on laser-induced optomechanical processing of silver colloids, for the preparation of polymer surfaces highly enriched with silver nanoparticles (AgNPs). As a result, the AgNPs are firmly immobilized in a thin surface layer without the use of any other chemical mediators. We have shown that our approach is applicable to a broad spectrum of polymer foils, regardless of whether they absorb laser light or not. However, if the laser radiation is absorbed, it is possible to transform smooth surface morphology of the polymer into a roughened one with a higher specific surface area. Analyses of the release of silver from the polymer surface together with antibacterial tests suggested that these materials could be suitable candidates in the fight against nosocomial infections and could inhibit the formation of biofilms with a long-term effect.

Crude polysaccharide extracts derived from Agaricus bisporus (A), A. brasiliensis (B), and Phellinus linteus (P) were used for the synthesis of silver nanoparticles (AgNPs, labeled AAgNP, BAgNP, PAgNP, respectively). UV and FT-IR spectra, size distribution, and zeta potential of the respective particles were recorded, and TEM and SEM-EDS characterization was done. UV-Vis spectroscopy showed maximum absorbance at 415 nm for A, at 400 nm for P, and at 420 nm for B. SEM-EDS analysis showed BAgNP to consist of almost 90% of silver, while silver content in AAgNP and PAgNP was much lower, 46.5 and 52.3%, respectively. Individual extracts as well as the Ag-NPs were tested against a panel of clinically isolated and ATCC derived pathogens. In almost all cases minimum inhibitory concentration (MIC) was significantly lower than those of antibiotics, suggesting up to 100 times more effectivity. BAgNP, PAgNP, and AAgNP appeared very active against Pseudomonas aeruginosa ATCC 27853 (MIC: 0.19, 0.19, 0.97 μg/mL, respectively). The same nanoparticles were also very effective toward Candida albicans ATCC 10231 (MIC: 0.39, 0.78, 0.97 μg/mL, respectively). Our study indicates that the bactericidal effect of PAgNP, AAgNP, BAgNP on E. coli 25922 ATCC (MBC: 1.56, 0.97, 6.25 μg/mL, respectively) is significantly more pronounced than that of amoxicillin. A pure solution of colloidal silver nanoparticles showed significantly weaker microbiostatic/microbiocidal potential than all tested mushroom extracts' AgNPs, as well as amoxicillin. Silver nanoparticles made with extracts of A, B, and P seem welcome as an addition to the inventory of antimicrobial compounds used in clinical medicine against bacterial and yeast infection.

In the coronavirus "infodemic," people are exposed to official recommendations but also to potentially dangerous pseudoscientific advice claimed to protect against COVID-19. We examined whether irrational beliefs predict adherence to COVID-19 guidelines as well as susceptibility to such misinformation. Irrational beliefs were indexed by belief in COVID-19 conspiracy theories, COVID-19 knowledge overestimation, type I error cognitive biases, and cognitive intuition. Participants (N = 407) reported (1) how often they followed guidelines (e.g., handwashing, physical distancing), (2) how often they engaged in pseudoscientific practices (e.g., consuming garlic, colloidal silver), and (3) their intention to receive a COVID-19 vaccine. Conspiratorial beliefs predicted all three outcomes in line with our expectations. Cognitive intuition and knowledge overestimation predicted lesser adherence to guidelines, while cognitive biases predicted greater adherence, but also greater use of pseudoscientific practices. Our results suggest an important relation between irrational beliefs and health behaviors, with conspiracy theories being the most detrimental.

Colloidal suspensions of silver nanoparticles (AgNPs) with surface modified by capping with citrate ions were synthesized by chemical reduction method. Transmission and Scanning Electron Microscopy as well as darkfield Optical Microscopy provided information on the nanoparticle morphology, with fine symmetrical grains and log-normal fitted size distribution. Small Angle X-ray Scattering method allowed theoretical confirmation of colloidal silver nanoparticle fine granularity, based on measurements in the native fluid sample. UV-Vis spectrophotometry allowed studying the Localized Surface Plasmon Resonance band versus the stability of the citrate-AgNP sample after storage and after UV-C exposure. The colloidal AgNP impact on Phanerochaete chrysosporium environmental microorganisms was studied by specific biochemical investigations. Silver released from the colloidal suspension of AgNPs was supposed to induce changes in some antioxidant enzymes and in some enzymes of Krebs' cycle. Catalase activity was moderately changed (an increase with over 50%) as well as superoxide dismutase activity, while the diminution of the activities of four dehydrogenases synthesized in the fungus mycelium was emphasized also: a decrease with about 60% for malate dehydrogenase, with over 50% for isocitrate dehydrogenase and succinate dehydrogenase and with about 40% for alpha-ketoglutarate dehydrogenase. These findings suggested the nano-toxicological issues of citrate-AgNPs impact on the environmental beneficial microorganisms.

Colloidal silver products are sold for a wide range of disinfectant and health applications. This has increased the potential for human exposure to silver nanoparticles (AgNPs) and ions (Ag+), for which oral ingestion is considered to be a major route of exposure. Our objective was to evaluate and compare the toxicity of two commercially available colloidal silver products on two human intestinal epithelial models under realistic exposure conditions. Mesosilver™ and AgC were characterized and a concentration range between 0.1 and 12 μg/mL chosen. Caco-2 cells vs. co-culture of Caco-2 and mucus-secreting HT29-MTX cells (90/10) were used. Repeated exposure was carried out to determine cell viability over 18 days of cell differentiation in 24-well plates. Selected concentrations (0.1, 1, and 3 μg/mL) were tested on cells cultured in E-plates and Transwells with the same repeated exposure regimen, to determine cell impedance, and cell viability and trans-epithelial electrical resistance (TEER), respectively. Silver uptake, intracellular localisation, and translocation were determined by CytoViva™, HIM-SIMS, and ICP-MS. Genotoxicity was determined on acutely-exposed proliferating Caco-2 cells by γH2AX immunofluorescence staining. Repeated exposure of a given concentration of AgC, which is composed solely of ionic silver, generally exerted more toxic effects on Caco-2 cells than Mesosilver™, which contains a mix of AgNPs and ionic silver. Due to its patchy structure, the presence of mucus in the Caco-2/HT29-MTX co-culture only slightly mitigated the deleterious effects on cell viability. Increased genotoxicity was observed for AgC on proliferating Caco-2 cells. Silver uptake, intracellular localisation, and translocation were similar. In conclusion, Mesosilver™ and AgC colloidal silver products show different levels of gut toxicity due to the forms of distinct silver (AgNPs and/or Ag+) contained within. This study highlights the applicability of high-resolution (chemical) imaging to detect and localize silver and provides insights into its uptake mechanisms, intracellular fate and cellular effects.

Novel SERS substrates is urgently in demand for rapid and sensitive analysis of toxic agrochemicals from food. In this work, a monodispersed tungsten disulfide quantum dots modified silver nanosphere (Ag@WS2QD) was prepared and used as SERS substrate. Ag@WS2QD generated uniform and stable SERS signals within 2 min, displaying great promise in "mixing and reading" detection. Compared to unmodified colloidal silver nanoparticles, 4 times higher analytical enhancement factor was found in Ag@WS2QD. Density functional theory calculation verified the enhanced charge transfer within the coupling systems of molecule-Ag@WS2QD. Besides, the unique surface properties are beneficial for the enrichment of specific molecule. Both the chemical extraction and enhanced charge transfer contributes to rapid and sensitive SERS detection of Ag@WS2QD. A "mixing and reading" SERS method for thiram from honey and four kinds of juice was developed from Ag@WS2QD, showing great promise for rapid and direct SERS detection for toxic agrochemicals and further applications.

The opioid crisis in the USA has resulted in over 702,000 overdose fatalities between 1999 and 2017 and can be attributed to over-prescription of opioids and abuse of synthetic opioids in combination with other illicit drugs. A rapid and sensitive SERS method has been developed for trace detection of opioids including fentanyl, hydrocodone, oxycodone, and tramadol in low-dosage suspect tablets using two different handheld Raman spectrometers equipped with 785 and 1064 nm lasers. The method involves a micro-extraction procedure using 10% methanol in deionized water, followed by filtration and addition of colloidal silver and aqueous KBr, resulting in a mixture that can be measured directly via a glass vial. The lowest concentration (Cmin) of fentanyl, tramadol, oxycodone, and hydrocodone standards that yielded a positive match was 250 ng/ml, 5, 10, and 10 μg/ml using the 1064 nm laser device and 100 ng/ml, 1 μg/ml, 500 ng/ml, and 750 ng/ml using the 785 nm laser device, respectively. For the analysis of suspect tablets containing these opioids, the Cmin ranges between 5 and 75 µg/ml for 1064 nm laser device and 1 and 50 µg/ml for 785 nm laser device. The overall positive identification rate for all the opioids studied in the suspect counterfeit tablets analyzed ranged from 80% to 100%. The use of SERS for rapid chemical identification at remote sampling sites, such as international mail facilities (IMFs) and express courier hubs (ECHs), provides a rugged, simple, and practical method applicable for point-of-entry sampling and analysis.