Towards the scale-up of the formation of nanoparticles on α-Ag2WO4 with bactericidal properties by femtosecond laser irradiation

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.

Disentangling the Effects of Laser and Electron Irradiation on AgX (X = Cl, Br, and I): Insights from Quantum Chemical Calculations

The effects on the lattice structure and electronic properties of different polymorphs of silver halide, AgX (X = Cl, Br, and I), induced by laser irradiation (LI) and electron irradiation (EI) are investigated using a first-principles approach, based on the electronic temperature (Te) within a two-temperature model (TTM) and by increasing the total number of electrons (Ne), respectively. Ab initio molecular dynamics (AIMD) simulations provide a clear visualization of how Te and Ne induce a structural and electronic transformation process during LI/EI. Our results reveal the diffusion processes of Ag and X ions, the amorphization of the AgX lattices, and a straightforward interpretation of the time evolution for the formation of Ag and X nanoclusters under high values of Te and Ne. Overall, the present work provides fine details of the underlying mechanism of LI/EI and promises to be a powerful toolbox for further cross-scale modeling of other semiconductors.

Tuning the morphology to enhance the catalytic activity of α-Ag2WO4 through V-doping

Here, we present the synthesis of a highly efficient V-doped α-Ag2WO4 catalyst for the oxidation of sulfides to sulfones, exhibiting a high degree of tolerance towards various sensitive functional groups. Remarkably, the catalysts with 0.01% V-doping content exhibited outstanding selectivity towards the oxidation process. Scavenger experiments indicated the direct involvement of electron-hole (e-/h+) pairs, hydroxyl radical (˙OH), and singlet oxygen (1O2) in the catalytic mechanism. Based on the experimental and theoretical results, the higher activity of the V-doped α-Ag2WO4 samples was associated with the preferential formation of the (100) surface in the catalyst morphology.

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

Silver tungstate (α-Ag2WO4), silver molybdate (β-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-1β, 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), β-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-1β 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, β-Ag2MoO4, and α-AgVO3 microcrystals.

Bactericidal activity of Ag4V2O7/β-AgVO3 heterostructures against antibiotic-resistant Klebsiella pneumoniae

Although Ag-based materials are efficient against antibiotic-resistant bacteria, their high toxicity to living organisms represents a major challenge for obtaining useful products. In this work, we report the bactericidal activity of Ag₄V₂O₇/β-AgVO₃ heterostructures, which proved to be effective against Klebsiella pneumoniae (ATCC 1706, a standard strain; A54970, a multidrug-resistant carbapenemase (KPC)-producing strain; A34057, a multidrug-resistant strain capable of producing extended spectrum beta-lactamases (ESBL); and a community-isolated strain, A58240) at minimum inhibitory concentrations (MIC) as low as 62.5 μg/mL. This activity is higher than that reported for the individual silver vanadates (Ag₄V₂O₇ or β-AgVO₃) owing to the synergistic interactions between both semiconductors. However, the most efficient heterostructure was found to be toxic to mouse 3 T3 fibroblasts and to L. sativa and C. sativus seeds, as indicated by MTT ((4,5 - dimethylthiazol -2yl) 2,5 -diphenylbromide), neutral red assays and germination index measurements. The antimicrobial, phytotoxic and cytotoxic activities were all associated with an efficient generation of reactive oxygen species (ROS) in the heterostructure, especially OH and O₂^- radicals. The ROS production by Ag₄V₂O₇/β-AgVO₃ heterostructures was measured through photodegradation studies with Rhodamine B. While the bactericidal activity of the heterostructures is promising, especially when compared to Ag-based materials, their use in practical applications will require encapsulation either to avoid leaching or to mitigate their toxicity to humans, animals and plants.

Inactivation of SARS-CoV-2 by a chitosan/α-Ag2WO4 composite generated by femtosecond laser irradiation

In the current COVID-19 pandemic, the next generation of innovative materials with enhanced anti-SARS-CoV-2 activity is urgently needed to prevent the spread of this virus within the community. Herein, we report the synthesis of chitosan/α-Ag₂WO₄ composites synthetized by femtosecond laser irradiation. The antimicrobial activity against Escherichia coli, Methicilin-susceptible Staphylococcus aureus (MSSA), and Candida albicans was determined by estimating the minimum inhibitory concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC). To assess the biocompatibility of chitosan/α-Ag₂WO₄ composites in a range involving MIC and MBC/MFC on keratinocytes cells (NOK-si), an alamarBlue™ assay and an MTT assay were carried out. The SARS-CoV-2 virucidal effects was analyzed in Vero E6 cells through viral titer quantified in cell culture supernatant by PFU/mL assay. Our results showed a very similar antimicrobial activity of chitosan/α-Ag₂WO₄ 3.3 and 6.6, with the last one demonstrating a slightly better action against MSSA. The chitosan/α-Ag₂WO₄ 9.9 showed a wide range of antimicrobial activity (0.49-31.25 µg/mL). The cytotoxicity outcomes by alamarBlue™ revealed that the concentrations of interest (MIC and MBC/MFC) were considered non-cytotoxic to all composites after 72 h of exposure. The Chitosan/α-Ag₂WO₄ (CS6.6/α-Ag₂WO₄) composite reduced the SARS-CoV-2 viral titer quantification up to 80% of the controls. Then, our results suggest that these composites are highly efficient materials to kill bacteria (Escherichia coli, Methicillin-susceptible Staphylococcus aureus, and the yeast strain Candida albicans), in addition to inactivating SARS-CoV-2 by contact, through ROS production.

Antifungal Activity and Biocompatibility of α-AgVO3, α-Ag2WO4, and β-Ag2MoO4 Using a Three-Dimensional Coculture Model of the Oral Mucosa

Fungal infections have become a major concern in the medical community, especially those caused by Candida spp. Within this species, Candida albicans stands out for being an opportunistic commensal fungus that can cause superficial and invasive infections. Current antifungal therapy involves the local and/or systemic use of drugs such as azoles, polyenes, and echinocandins. These antifungals are based on highly specific target sites, and the development of resistance may occur with changes in the enzymatic pathways that serve as the drug targets. Thus, the development of new antifungal drugs is highly recommended to prevent drug resistance. The present investigation evaluated the antifungal activity of silver-containing microcrystals such as silver vanadate (α-AgVO₃), silver tungstate (α-Ag₂WO₄), and silver molybdate (β-Ag₂MoO₄). In addition to having antimicrobial activity, such compounds should not cause damage to underlying tissues. Thus, to better assess the biocompatibility of new compounds, a new three-dimensional (3D) coculture model involving three cell lines was developed. The validation of the model was based on fluorescent markers and confocal laser microscopy. The biocompatibility of silver-containing microcrystals was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. 3D coculture was infected with C. albicans biofilm and challenged with α-AgVO₃, α-Ag₂WO₄, and β-Ag₂MoO₄. The action of microcrystals on C. albicans biofilm was evaluated by colony-forming units (CFU/ml) and LIVE/DEAD staining. In addition, production of proinflammatory cytokines interleukin 6 (IL-6), IL-8, IL-1β, and tumor necrosis factor α (TNF-α) was measured by cytometric bead array kit using flow cytometry. The 3D coculture model described here proved to be adequate to assess both the biocompatibility of the new materials and the infectious processes. Regarding the biocompatibility of the microcrystals, only α-AgVO₃ (15.62 µg/ml) showed a decrease in cell viability. The antibiofilm activity of α-Ag₂WO₄ was similar to that of the standard drug (fluconazole). Although α-Ag₂WO₄ was able to induce the production of IL-6, IL-8, and IL-1β, no differences in cytokine production were observed between noninfected and infected models treated with this microcrystal. β-Ag₂MoO₄ inhibits the production of TNF-α in the infected model; however, it showed no antibiofilm activity. Based on the biocompatibility and antifungal findings, α-Ag₂WO₄ is a promising material for treating C. albicans infection.

Toxicity of α-Ag2WO4 microcrystals to freshwater microalga Raphidocelis subcapitata at cellular and population levels

Silver-based materials have microbicidal action, photocatalytic activity and electronic properties. The increase in manufacturing and consumption of these compounds, given their wide functionality and application, is a source of contamination to freshwater ecosystems and causes toxicity to aquatic biota. Therefore, for the first time, we evaluated the toxicity of the silver tungstate (α-Ag₂WO₄), in different morphologies (cube and rod), for the microalga Raphidocelis subcapitata. To investigate the toxicity, we evaluated the growth rate, cell complexity and size, reactive oxygen species (ROS) production and chlorophyll a (Chl a) fluorescence. The α-Ag₂WO₄ - R (rod) was 1.7 times more toxic than α-Ag₂WO₄-C (cube), with IC₁₀ and IC₅₀ values of, respectively, 8.68 ± 0.91 μg L^-1 and 13.72 ± 1.48 μg L^-1 for α-Ag₂WO₄ - R and 18.60 ± 1.61 μg L^-1 and 23.47 ± 1.16 μg L^-1 for α-Ag₂WO₄-C. The release of silver ions was quantified and indicated that the silver ions dissolution from the α-Ag₂WO₄ - R ranged from 34 to 71%, while the Ag ions from the α-Ag₂WO₄-C varied from 35 to 97%. The α-Ag₂WO₄-C induced, after 24 h exposure, the increase of ROS at the lowest concentrations (8.81 and 19.32 μg L^-1), whereas the α-Ag₂WO₄ - R significantly induced ROS production at 96 h at the highest concentration (31.76 μg L^-1). Both microcrystal shapes significantly altered the cellular complexity and decreased the Chl a fluorescence at all tested concentrations. We conclude that the different morphologies of α-Ag₂WO₄ negatively affect the microalga and are important sources of silver ions leading to harmful consequences to the aquatic ecosystem.

PVC-SiO2-Ag composite as a powerful biocide and anti-SARS-CoV-2 material

The ongoing COVID-19 pandemic has pushed scientists and technologists to find novel strategies to develop new materials to prevent the transmission, spread, and entry of pathogens into the human body. In this report, the fabrication of polyvinyl chloride (PVC)-SiO₂-Ag composite is presented, in which the percentage of Ag is 0.84% wt. Our findings render that this composite eliminates (> 99.8%) bacteria and fungus (Staphylococcus aureus, Escherichia coli, Penicillium funiculosum) and SARS-CoV-2, by surface contact in 2 h hours and 15 min, respectively. Specific migration analysis shown that the use of the PVC-SiO₂-Ag composite is considered safe and effective for food preservation. This research and innovation front can be considered a breakthrough for the design of biocide materials. Future directions for this exciting and highly significant research field can open the door to the development of new technologies for the fabrication of packaging films to protect consumer products (such as fruits, vegetables, and other foods).

SiO2-Ag Composite as a Highly Virucidal Material: A Roadmap that Rapidly Eliminates SARS-CoV-2

COVID-19, as the cause of a global pandemic, has resulted in lockdowns all over the world since early 2020. Both theoretical and experimental efforts are being made to find an effective treatment to suppress the virus, constituting the forefront of current global safety concerns and a significant burden on global economies. The development of innovative materials able to prevent the transmission, spread, and entry of COVID-19 pathogens into the human body is currently in the spotlight. The synthesis of these materials is, therefore, gaining momentum, as methods providing nontoxic and environmentally friendly procedures are in high demand. Here, a highly virucidal material constructed from SiO2-Ag composite immobilized in a polymeric matrix (ethyl vinyl acetate) is presented. The experimental results indicated that the as-fabricated samples exhibited high antibacterial activity towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as well as towards SARS-CoV-2. Based on the present results and radical scavenger experiments, we propose a possible mechanism to explain the enhancement of the biocidal activity. In the presence of O2 and H2O, the plasmon-assisted surface mechanism is the major reaction channel generating reactive oxygen species (ROS). We believe that the present strategy based on the plasmonic effect would be a significant contribution to the design and preparation of efficient biocidal materials. This fundamental research is a precedent for the design and application of adequate technology to the next-generation of antiviral surfaces to combat SARS-CoV-2.

Rapid reduction of nitroarenes photocatalyzed by an innovative Mn3O4/α-Ag2WO4 nanoparticles

A novel photocatalyst based on the design of P-N heterojunction between hollow spherical Mn3O4 and nanorods shape of α-Ag2WO4 is synthesized using a sonication-deposition-precipitation route. The nanocomposite Mn3O4/α-Ag2WO4(60%) exhibits a great potential towards nitroarenes (including 4-nitrophenol, 4-nitro-aniline and 4-Nitro-acetanilide) reduction under visible light irradiation exceeding that of Mn3O4/α-Ag2WO4(40%) as well as their individual counterparts (3-5%). The Mn3O4/α-Ag2WO4(60%) catalyst exhibited an excellent photo-reduction activity comprised of 0.067 s-1 towards 4-nitrophenol (0.001 M) in only 60 s reaction time using NaBH4 (0.2 M). This was due to the successful formation of the Mn3O4/α-Ag2WO4 composite as validated by XRD, TEM-SAED, XPS, FTIR, UV-Vis diffuse reflectance and PL techniques. Decreasing the Eg value into 2.7 eV, the existence of a new (151) plane in the composite beside enhancement of the composite electrical conductivity (1.66 × 10-7 Ω-1 cm-1) helps the facile nitroarenes adsorption and hydrogenation. Transient photocurrent response and linear sweep voltammetry results prove the facilitation of photogenerated charge carriers separation and transport via improving electron lifetime and lessening recombination rate. The composite photocatalyst produced higher amounts of H2 production, when inserted in a typical reaction medium containing NaBH4, comprised of 470 µ mole/g exceeding those of the counterparts (35 µ mole/g). This photocatalyst is strikingly hydrogenated 4-nitrophenol under mild conditions (25 °C and 0.35 MPa pressure of H2) with magnificent rate constant equal 34.9 × 10-3 min-1 with 100% selectivity towards 4-aminophenol.

Unconventional Magnetization Generated from Electron Beam and Femtosecond Irradiation on α-Ag2WO4: A Quantum Chemical Investigation

Novel magnetic metals and metal oxides that use both the spin and charge of an electron offer exciting technological applications. Their discovery could boost research on functional nanoscale materials. Here, for the first time, we report the magnetization of α-Ag2WO4 under electron beam and femtosecond laser irradiation. The formation and growth of silver oxides (AgO, Ag2O, and Ag3O4) and Ag nanofilaments can be observed on the surface of α-Ag2WO4 crystals. These features were also present in the composition of an extruded material and could open new avenues for surface magnetism studies. In order to understand these results, we used first-principles density functional theory calculations. This allowed us to investigate several potential scenarios for controlling magnetic properties. The effect of electron addition on the crystalline structures of α-Ag2WO4, Ag3O4, Ag2O, and AgO has been analyzed in detail. The creation of Ag and O vacancies on these compounds was also analyzed. Based on structural and electronic changes at the local coordination site of Ag, a mechanism was proposed. The mechanism illustrates the processes responsible for the formation and growth of metallic Ag and the magnetic response to electron beam irradiation.

Femtosecond-laser-irradiation-induced structural organization and crystallinity of Bi2WO6

Controlling the structural organization and crystallinity of functional oxides is key to enhancing their performance in technological applications. In this work, we report a strong enhancement of the structural organization and crystallinity of Bi2WO6 samples synthetized by a microwave-assisted hydrothermal method after exposing them to femtosecond laser irradiation. X-ray diffraction, UV-vis and Raman spectroscopies, photoluminescence emissions, energy dispersive spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy were employed to characterize the as-synthetized samples. To complement and rationalize the experimental results, first-principles calculations were employed to study the effects of femtosecond laser irradiation. Structural and electronic effects induced by femtosecond laser irradiation enhance the long-range crystallinity while decreasing the free carrier density, as it takes place in the amorphous and liquid states. These effects can be considered a clear cut case of surface-enhanced Raman scattering.

Femtosecond laser self-assembly for silver vanadium oxide flower structures

Flower-like silver vanadium oxide (SVO) micropatterns were realized by femtosecond laser in situ writing from its precursor. Self-assembled petals irradiated by a femtosecond laser were observed standing on the substrate along the scanned routine assisted by the formation of silver seeds and plasmonic-mediated effects. By controlling the concentration of ammonium monovanadate and the laser exposure time, a different thickness of petals was manipulated from ∼100  nm to micrometers. The SVO products were confirmed Ag₄V₂O₇, AgVO₃, and part of Ag₃VO₄ by x-ray diffraction (XRD) measurement. Photon-driven self-assembly for in situ fabrication of microstructures looks to be an effective and facile technique for SVO and other functional compounds.

Antimicrobial properties of α-Ag2WO4 rod-like microcrystals synthesized by sonochemistry and sonochemistry followed by hydrothermal conventional method

In this study we report the synthesis of silver tungstate microcrystals (α-Ag₂WO₄) by sonochemistry method (SC) at 65 °C and sonochemistry followed by conventional hydrothermal (SC + HC) for 1, 6 and 12 h, at 140 °C. The structural characterization by XRD confirms the alpha phase of the orthorhombic structure and the space group Pn2n, for all synthesized microcrystals. All the actives modes identified at the Raman spectroscopy were characteristic of alpha phase. The optical band gap by UV-Vis spectroscopy using the diffuse reflectance were 2.98, 3.0, 2.99 and 2.96 eV, for the microcrystals SC, SC + HC-1 h, SC + HC-6 h and SC + HC-12 h, respectively. FE-SEM images show the rod-like microcrystals, however, exhibiting the plane surface (1 0 1) only for the synthesized microcrystals with the assistance of the hydrothermal method (SC + HC-1 h, SC + HC- 6 h and SC + HC-12 h). The antimicrobial potential was confirmed for all α-Ag₂WO₄ microcrystals synthesized. However, the SC + HC-12 h microcrystals were more susceptible in the bacterial and fungal inhibition, with MIC values for microorganisms C. albicans, T. rubrum, MRSA e EHEC, 0.2-0.5, 4-9, 250 and 31.25 μg mL^-1, respectively.

Ag Nanoparticles/α-Ag2WO4 Composite Formed by Electron Beam and Femtosecond Irradiation as Potent Antifungal and Antitumor Agents

The ability to manipulate the structure and function of promising systems via external stimuli is emerging with the development of reconfigurable and programmable multifunctional materials. Increasing antifungal and antitumor activity requires novel, effective treatments to be diligently sought. In this work, the synthesis, characterization, and in vitro biological screening of pure α-Ag₂WO₄, irradiated with electrons and with non-focused and focused femtosecond laser beams are reported. We demonstrate, for the first time, that Ag nanoparticles/α-Ag₂WO₄ composite displays potent antifungal and antitumor activity. This composite had an extreme low inhibition concentration against Candida albicans, cause the modulation of α-Ag₂WO₄ perform the fungicidal activity more efficient. For tumor activity, it was found that the composite showed a high selectivity against the cancer cells (MB49), thus depleting the populations of cancer cells by necrosis and apoptosis, without the healthy cells (BALB/3T3) being affected.

S. S, R. A. R, M. A, R. TM, H. BM, G. MV, E. C, J. A, E. L. Laser and electron beam-induced formation of Ag/Cr structures on Ag2CrO4

The interactions of silver chromate with a femtosecond laser and electron beam irradiations were investigated.

From Complex Inorganic Oxides to Ag-Bi Nanoalloy: Synthesis by Femtosecond Laser Irradiation

Bimetallic nanoalloys with a wide variety of structures and compositions have been fabricated through many diverse techniques. Generally, various steps and chemicals are involved in their fabrication. In this study, the synthesis of Ag-Bi nanoalloys by femtosecond laser irradiation of an inorganic oxide Ag₂WO₄/NaBiO₃ target without any chemicals like reducing agents or solvent is presented. The interaction between these materials and the ultrashort pulse of light allows the migration of Ag and Bi atoms from the crystal lattice to the particles surfaces and then to the plasma plume, where the reduction of the positively charged Ag and Bi species in their respective metallic species takes place. Subsequently, the controlled nucleation and growth of the Ag-Bi alloyed nanoparticles occurs in situ during the irradiation process in air. Although at the bulk level, these elements are highly immiscible, it was experimentally demonstrated that at nanoscale, the Ag-Bi nanoalloy can assume a randomly mixed structure with up to 6 ± 1 atom % of Bi solubilized into the face-centered cubic structure of Ag. Furthermore, the Ag-Bi binary system possesses high antibacterial activity against Staphylococcus aureus (methicillin-resistant and methicilin-susceptible), which is interesting for potential antimicrobial applications, consequently increasing their range of applicability. The present results provide potential insights into the structures formed by the Ag-Bi systems at the nanoscale and reveal a new processing method where complex inorganic oxides can be used as precursors for the controlled synthesis of alloyed bimetallic nanoparticles.

Printable nanocomposites of polymers and silver nanoparticles for antibacterial devices produced by DoD technology

Silver nanoparticles (Ag-NPs) are known for their efficient bactericidal activity and are widely used in industry. This study aims to produce printable antibacterial devices by drop-on-demand (DoD) inkjet technology, using Ag-NPs as the active part in complex printable fluids. The synthesis of this active part is described using two methods to obtain monodisperse NPs: chemical and microwave irradiation. The synthesized NPs were characterized by UV-VIS, STEM, TEM, DLS and XRD. Two printable fluids were produced based: one with Ag-NPs and a second one, a polymeric nanocomposite, using silver nanoparticles and polyvinyl butyral (Ag-NPs/PVB). Cellulose acetate was used as a flexible substrate. The ecotoxicity analysis of fluids and substrate was performed with Artemia franciscana nauplii. Optimized electric pulse waveforms for drop formation of the functional fluids were obtained for the piezoelectric-based DoD printing. Activity of printed antibacterial devices was evaluated using the Kirby-Bauer method with Staphylococcus aureus and Escherichia coli. The results show that the printed device with Ag-NP fluids evidenced a bacterial inhibition. An important advantage in using the DoD process is the possibility of printing, layer by layer or side by side, more than one active principle, allowing an interleaved or simultaneous release of silver NP and other molecules of interest as for example with a second functional fluid to ensure effectiveness of Ag activity.

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.