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The paper discusses the results of the electrosynthesis of metal–polymer nanocomposites of silver and coatings on pure iron and steel electrodes by combining the process of electropolymerization of 1-vinyl-1,2,4-triazole (VT) with N-vinyl-caprolactam (VC) and cathodic precipitation of metals. During the electrolysis of aqueous and water–ethanol solutions of VT with VC at various ratios in the presence of AgNO3, metal nanocomposites and coatings are formed on purely iron and steel electrodes. The structure and composition of the synthesized metal nanocomposites were confirmed by various physicochemical methods, such as electron and IR spectroscopic, X-ray phase and thermogravimetric, elemental analyses, as well as by transmission electron microscopy. In the electronic spectra of nanocomposites, absorption bands appear with a maximum at 405–421 nm, which is typical for systems with zero-valent silver. The IR spectra show that the matrix structure hardly changes during the formation of nanocomposites and coatings. At high current densities (j ≥ 10 mA/sm2), nanocomposite films are formed on the electrode surface. The silver content in nanocomposites is 0–9%, which leads to an increase in the viscosity of nanocomposite solutions compared to solutions of the initial copolymers. Increasing the silver content above 8% will lead first to a partial and then to a complete loss of solubility. According to the data of transmission electron macroscopy, the synthesized polymer nanocomposites consist of isolated silver nanoparticles, predominantly spherical in shape, uniformly distributed in the bulk of the polymer matrix. The size dispersion of nanoparticles depends on the silver content in the nanoparticles. The thermal decomposition of metal nanocomposites occurs in stages. [ABSTRACT FROM AUTHOR]

This paper presents the syntheses of SiO2 particles immobilized with Ag nanoparticles and their composite with Au. Ag nanoparticles are present on the surfaces of the SiO2 particles, and Ag+ ions are galvanically replaced with Au3+ ions. Finally, a method for maintaining the color durability and dispersibility of the Ag nanoparticles is demonstrated. The particles are primarily synthesized in three steps: In the first step, Sn2+ ions are adsorbed on the surfaces of the SiO2 particles; in the second step, Ag+ ions are added, which are reduced and simultaneously adsorbed on the surface while Sn2+ is oxidized to Sn4+; in the third step, Au3+ ions are reduced by galvanic replacement and deposited on the Ag surface. Extensive characterization using transmission electron microscopy, scanning transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy reveals that the Ag–Au composite nanoparticles (17.2 ± 4.1 nm) are immobilized on the surface of the SiO2 particles (<1 µm). The morphology and coloration of the SiO2 particles with the immobilized Ag–Au composite nanoparticles remain preserved in nitric acid. This preservation is more pronounced than that observed in SiO2 particles with immobilized Ag nanoparticles. This enhanced durability can be attributed to the formation of stable bonds between Ag and Au. [ABSTRACT FROM AUTHOR]

Polymer nanocomposite materials with catalytic activity were designed via modification of MF-4SK ion-exchange membranes with Au and Ag nanoparticles obtained according to various synthetic methods in reverse micellar solutions. A sufficient transparency of the films allowed us to detect nanoparticles in the films using UV–Vis spectrophotometry, monitoring changes in the content of metal nanoparticles in the reverse micellar solution. A different mechanism of interaction of Au and Ag nanoparticles obtained by the same synthetic method with the MF-4SK film upon their contact with its surface was discovered, the destruction of nanoparticles was observed, and the influence of mechanism of primary acts in the formation of metal nanoparticles in reverse micellar solutions on their adsorption properties was confirmed. The highest concentration of gold nanoparticles was found in films immersed in reverse micellar solutions at the time of their exposure to ionizing radiation. [ABSTRACT FROM AUTHOR]

The development of an effective and eco-friendly silver nanoparticle (AgNPs) to abate the effect of abiotic stress is an important area of nano-biotechnology. This study aimed to study the priming effect of plant-based green-synthesized silver nanoparticles and melatonin on the physiological and biochemical activities of drought-stressed E. uniflora. Sterilized seeds of E. uniflora were primed with 0.06 mg/l of ML-AgNPs, 0.06 mg/l of melatonin, and a nano-silver formulation of melatonin (1:1). Primed seeds were planted and subjected to 7 days under drought stress. The ML-AgNPs enhanced germination percentage, speed and vigor, and shoot elongation and induced the production of APx, CAT, and proline dehydrogenase (100% increases). Melatonin improved the activities of APx and CAT, total protein, accumulation of proline, and proline dehydrogenase (200% increases) and stabilized MDA content. Meanwhile, silver nano-formulation of melatonin increased leaves proliferation of leaves and production of APx, GPx, SOD, and CAT. Accumulation of proline and 100% upregulation of proline dehydrogenase osmo-regulated the effects of the drought, reduced MDA contents, and stabilized the excessive production of H2O2 and O2−. The ML-AgNO3 showed an efficient delivery system of melatonin into the plant under drought stress. As a result, our research shows that melatonin in silver nano-formulation (1:1) is a useful biostimulant against drought stress. [ABSTRACT FROM AUTHOR]

Gold and silver nanoparticles have witnessed increased scientific interest due to their colourful colloidal solutions and exceptional applications. Comparing the localized surface plasmon resonance (LSPR) of gold and silver nanoparticles is crucial for understanding and optimizing their optical properties. This comparison informs the design of highly sensitive plasmonic sensors, aids in selecting the most suitable nanoparticles for applications like surface-enhanced infrared spectroscopy (SEIRA) and biomedical imaging, and guides the choice between gold and silver nanoparticles based on their catalytic and photothermal properties. Ultimately, the study of LSPR facilitates the tailored use of these nanoparticles in diverse scientific and technological applications. Two SEIRA methods combined with partial least squares regression (PLSR) chemometric tools were developed. This development is based on the synthesis of homogeneous, high-dense deposited metal nanoparticle islands over the surface of glass substrates to be used as lab-on-chip SEIRA sensors for the determination of bisacodyl (BIS) and its active metabolite in plasma. SEM micrographs revealed the formation of metallic islands of colloidal citrate-capped gold and silver nanoparticles of average sizes of 29.7 and 15 nm, respectively. BIS and its active metabolite were placed on the nanoparticles' coated substrates to be directly measured, then PLSR chemometric modelling was used for the quantitative determinations. Plasmonic citrate-capped gold nanoparticle substrates showed better performance than those prepared using citrate-capped silver nanoparticles in terms of preparation time, enhancement factor, PLSR model prediction, and quantitative results. This study offers a way to determine BIS and its active metabolite in the concentration range 15–240 ng/mL in human plasma using inexpensive disposable glass-coated substrates that can be prepared in 1 h to get results in seconds with good recovery between 98.77 and 100.64%. The sensors provided fast, simple, selective, molecular-specific and inexpensive procedures to determine molecules in their pure form and biological fluid. [ABSTRACT FROM AUTHOR]

Occupational health must be strictly considered in industries particularly in nanoparticle factories where workers were exposed to different types of chemicals. We measured the serum levels of inflammatory cytokines in workers who developed skin lesions after exposure to silver and silica nanoparticles. Using a questionnaire in this cross-sectional study, we identified 110 workers in nanoparticle industries who were exposed to silver and silica nanoparticles. We also included 40 healthy subjects as controls from the administrative department of the same factories who were not exposed to nanoparticles. Peripheral blood samples used to measure the mRNA levels of inflammatory cytokines by qRT-PCR. In comparison with the control group, the workers who developed skin lesions had significantly higher levels of interleukin IL4, IL6, IL8, and TNF-α, particularly after two or three decades of exposure to silver and silica nanoparticles. Participants who were exposed to silver had higher levels of IL6 and IL8 compared with those who were exposed to silica. Necessary measures must be considered to protect workers in nanoparticle industries against the potential toxic effects of these compounds. Our network pharmacology study suggests corresponding biochemical pathways for these disorders. [ABSTRACT FROM AUTHOR]

New silver complexes [Ag(bipy)(CH3COCHCOR)]x with 2,2′-bipyridine (bipy) and β-diketonate ligands (tfac: R = CF3, x = 2; hfbac: R = C3F7, x = 1) are prepared as part of the search for precursors for the vapor deposition of films and silver nanoparticles. The compounds are characterized by elemental analysis, IR and 1H NMR spectroscopy; their crystal structures are determined by XRD. Both complex are molecular due to the bidentate-cyclic coordination of both ligands. The [Ag(bipy)(hfbac)] molecules are mononuclear due to the steric effect of the extended perfluoroalkyl chain. For L = tfac, a binuclear complex is formed due to the coordination of the methine carbon atom. Thermal properties of the new complexes are studied by TGA and DSC and compared with those of the known hexafluoroacetylacetonate analog [Ag(bipy)(hfac)]2. The temperatures and thermodynamic parameters of melting are determined for all the studied compounds. [ABSTRACT FROM AUTHOR]

The combination of ultrasound and microreactors for the synthesis of nanomaterials is becoming increasingly popular, but effectively altering the ultrasonic field at the microscale to control the crystallization process remains a challenge. Herein, we investigated numerically and experimentally the effects of the ultrasonic field on the synthesis of boron-doped carbon nitride supported silver nanoparticles based on our homemade ultrasound-assisted coiled flow inverter microreactor (UCFIR). Specifically, the ultrasound promotes the radial mixing in the coiled flow inverter microreactor, even under low Reynolds number 10, resulting in better control over the crystallization process. The effects of key parameters, such as ultrasonic field distribution and ultrasonic power, on the particle size and size distribution of Ag/B-g-C3N4 have been demonstrated. The results show that when the ultrasound transducer is positioned on the 'abc' sides, the Ag/B-g-C3N4 with small and uniform Ag particles (4.12 ± 1.12 nm) can be obtained. As ultrasound power increased (0–176 W) and residence time decreased (17.5–140 s), the size of silver nanoparticles decreased, and their distribution narrowed. [ABSTRACT FROM AUTHOR]

Polyethylene glycol-6000 (PEG-6000) and trisodium citrate dihydrate (TSC) form an aqueous two-phase system (ATPS). This ATPS has been explored for synthesis and separation of silver nanoparticles (AgNPs). However, synthesis of stable nanoparticles using high TSC concentration corresponding to generic ATPS composition is not possible as high ionic strength of TSC causes aggregation and precipitation of silver nuclei. In the current study, this problem was overcome by synthesizing AgNPs at low concentrations of TSC. A two-step process was used for simultaneous synthesis and separation of AgNPs. Once stable nanoparticles were synthesised at low TSC concentration, the solution was taken to biphasic ATPS composition by mixing higher concentrations of TSC and PEG-6000 solutions to ensure particle entrapment. A silver to TSC (Ag+:TSC) molar ratio ≥ 67 × 10–3 that corresponds to lower TSC concentrations resulted in the formation of stable silver nanoparticles. The synthesis was carried out in batch and continuous modes. Spherical particles of average size 9.1 ± 3.4 nm were obtained in batch mode while in the continuous mode, the size was 10.6 ± 2.5 nm. Addition of polyvinylpyrrolidone (PVP) helped in sterically stabilizing the particles. Spontaneous formation and stabilization of AgNPs were observed within 15 min of reaction time as opposed to several hours reported in literature. The adopted synthesis route thus, is an effective green process to synthesise stable nanoparticles of silver which can be used in biological applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNP) can help prevent infection of virus and bacteria. The size and morphology of AgNP can be crucial to function, with smaller nanoparticles (< 20 nm) able to penetrate the cell wall. This is significant as oxidative stress and genotoxicity are associated with some sizes and coatings of AgNP, contraindicating the use of AgNP to reduce infection. We present evidence that a microfluidic chip can synthesize larger sizes and distributions of AgNP from the nano-to-micro size range. We show results from a microfluidic mixing chip that can produce a wide range of nano-to-micro size (~ 24–400 nm) AgNP. Synthesis is based on a modified Turkevich method, using a single-step AgNP synthesis on the microfluidic chip using two chemical components, trisodium citrate (NaCit) and AgNO3. To make AgNP more accessible, we describe the microfluidic chip and conditions capable of synthesis. We also describe how modification of flow rate and chemical reagent concentration change particle diameter during production. In our experiments, we found that AgNP production created a visible adsorption line in the microfluidic device, possibly owing to AgNP surface interaction at the polydimethylsiloxane (PDMS) interface. We characterize these particles with dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Based on optical light microscopy, we hypothesize that AgNP formation primarily occurs at the interface between the two chemical reagent streams. We also conclude that AgNP size increases could be due to interaction with the PDMS surface, which is known to be porous. Future work will help to understand how surface interaction may influence the formation of larger particles. [ABSTRACT FROM AUTHOR]

This study focuses on tumor therapy using two biocompatible silver nanoplatforms of chamomile extract and its active ingredient apigenin-7-glucoside. Chamomile silver nanoparticles (Ch-AgNPs) and apigenin 7- glucoside silver nanoparticles (Ap-AgNPs) were synthesized and characterized using different analytical techniques. On a stable nanoplatform with spherical nanoparticles in a narrow size range, both Ch-AgNP and Ap-AgNP exhibit potent cytotoxic effects against two different cell lines (HepG2 and MCF7). The synthesized NPs were radiolabeled with 131I giving high radiochemical purity. Biodistribution studies in tumor-bearing Albino mice showed higher accumulation in tumor sites compared to normal muscle. In conclusion, after further preclinical studies, both chamomile silver nanoparticles (Ch-AgNPs) and apigenin-7-glucoside silver nanoparticles (Ap-AgNPs) can be used as potential drugs for tumor theranostics. [ABSTRACT FROM AUTHOR]

Selective and sensitive detection of halides in water is critically important in the diagnosis of diseases and assessment of aquatic ecosystems. The recognition is usually carried out by numerous analytical techniques such as ion chromatography, fluorescence, near-infrared spectroscopy, ion-selective electrode and light scattering. Although these methods offer high sensitivity, they are expensive and time-consuming. Therefore, great efforts have been focused on the sensing of halide anions in water through a simple, fast, low-cost and portable paper-based colorimetric platform. In particular, the sensing process with silver nanoparticles interacting with analytes is of great chemical and biological interest. In this work, anisotropic silver nanoparticles in size and shape embedded in epoxy resin were prepared and subsequently printed on filter papers of cellulose. The influence of water and halide anions (Cl−, Br− and I−) on the morphology of these nanoparticles are investigated by scanning electron microscopy, Raman shift and diffuse reflectance spectroscopy. The mechanism involves aggregation of faceted silver nanoparticles induced by interactions between carbonyl groups of the resin and water. Subsequently, the interaction between halide anions and the aggregated silver nanoparticles causes oxidative etching on their surface, shape conversion (faceted to quasi-spherical shapes), decreasing in the particle size and formation of chain–like or compact aggregates resulting in strong interparticle plasmonic coupling. This selective mechanism was tested for the naked-eye colorimetric recognition of chloride anions in a complex simulated physiological system, whose results show promising perspectives to develop diagnostic-sensing devices. [ABSTRACT FROM AUTHOR]

This study marks a pioneering effort in utilizing Vachellia tortilis subsp. raddiana (Savi) Kyal. & Boatwr., (commonly known as acacia raddiana) leaves as both a reducing and stabilizing agent in the green "eco-friendly" synthesis of silver nanoparticles (AgNPs). The research aimed to optimize the AgNPs synthesis process by investigating the influence of pH, temperature, extract volume, and contact time on both the reaction rate and the resulting AgNPs' morphology as well as discuss the potential of AgNPs in detecting some heavy metals. Various characterization methods, such as UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), Zeta sizer, EDAX, and transmitting electron microscopy (TEM), were used to thoroughly analyze the properties of the synthesized AgNPs. The XRD results verified the successful production of AgNPs with a crystallite size between 20 to 30 nm. SEM and TEM analyses revealed that the AgNPs are primarily spherical and rod-shaped, with sizes ranging from 8 to 41 nm. Significantly, the synthesis rate of AgNPs was notably higher in basic conditions (pH 10) at 70 °C. These results underscore the effectiveness of acacia raddiana as a source for sustainable AgNPs synthesis. The study also examined the AgNPs' ability to detect various heavy metal ions colorimetrically, including Hg2+, Cu2+, Pb2+, and Co2+. UV–Vis spectroscopy proved useful for this purpose. The color of AgNPs shifts from brownish-yellow to pale yellow, colorless, pale red, and reddish yellow when detecting Cu2+, Hg2+, Co2+, and Pb2+ ions, respectively. This change results in an alteration of the AgNPs' absorbance band, vanishing with Hg2+ and shifting from 423 to 352 nm, 438 nm, and 429 nm for Cu2+, Co2+, and Pb2+ ions, respectively. The AgNPs showed high sensitivity, with detection limits of 1.322 × 10–5 M, 1.37 × 10–7 M, 1.63 × 10–5 M, and 1.34 × 10–4 M for Hg2+, Cu2+, Pb2+, and Co2+, respectively. This study highlights the potential of using acacia raddiana for the eco-friendly synthesis of AgNPs and their effectiveness as environmental sensors for heavy metals, showcasing strong capabilities in colorimetric detection. [ABSTRACT FROM AUTHOR]

Three types of silver/silver chloride nanoparticles were obtained by green synthesis from three types of microbial biomass. Their biocidal capacity was tested against six microorganisms. Two filamentous fungi were used that had previously demonstrated the ability to synthesise nanoparticles, Penicillium sp. 8L2 and Botryosphaeria rhodina MAMB-05. Also, the synthesis capacity of a yeast, Rhodotorula mucilaginosa 1S1, was evaluated. The original protocols underwent slight modifications. At the same time, the fractional inhibitory concentration was obtained. The interaction between specific antibiotics and the nanoparticles that showed the greatest biocidal capacity came from Penicillium sp.8L2, and it was studied further. All nanoparticles were characterised by UV–vis spectrophotometry and transmission electron microscopy (TEM). Also, their size distribution was analysed, which was in the range of 4 to 34 nm. The biocidal capacity of the nanoparticles for a group of bacteria and fungi was studied, presenting very low values in the range of 2.5–10 µg/mL for bacteria and 4–256 µg/mL for fungi. The interactions between the nanoparticles synthesised by Penicillium sp. 8L2 and a group of specific antibiotics for the tested microorganisms were also studied, proving that there was a synergistic interaction with vancomycin and ciprofloxacin and Staphylococcus epidermidis CECT 4183 and Escherichia coli CECT 101 bacteria, respectively. [ABSTRACT FROM AUTHOR]

A polyvinylpyrrolidone-capped (PVP-capped) strategy is reported to synthesize Ag NPs on silicon wafers via galvanic replacement reaction for SERS detection of adenine, where PVP acts as stabilizing agent in synthesis and efficient enrichment in detection. The morphologies of Ag NPs are optimized with uniform particle size by adjusting synthesis conditions, which hold excellent SERS performances like a high enhancement factor of 1.42 × 106, good uniform, reproducibility, and transferable nature. With the protection of the capped PVP, the Ag NPs keep excellent SERS properties even against harsh conditions of high temperature (100 ℃) and strong acid and base for 24 h. Utilizing the structural feature of PVP with abundant carbonyl groups, the PVP-capped Ag NPs achieve efficient enrichment of adenine through hydrogen bonding and π-interactions, which is analyzed by density functional theory. Quantitative detection of adenine is performed with a wide linear range from 10−4 to 10−8 M and a low limit of detection of 1 nM. Detection of adenine in human urine samples is achieved with a recovery of 99.1–103.4% and an RSD of less than 5%. [ABSTRACT FROM AUTHOR]

Current work presents a detailed study on the synthesis of silver nanoparticles (70 ± 5 nm) functionalized with 4-mercaptobenzoic acid and their interaction with divalent ions (Cu2+, Fe2+, Co2+, Ni2+, Pb2+, Mn2+, Zn2+, Sn2+). The study reveals the morphological changes in the nanoparticles due to interaction with Cu2+, resulting in the formation of larger nanoparticle aggregates. The UV-Vis spectra of the pristine and aggregated nanoparticles are also discussed, providing insights into the changes in their optical properties. These nanoparticles are used to detect divalent ions using surface-enhanced Raman spectroscopy with a detection limit of 2.5 × 10–7 M for Cu2+ and also show a linear response within the 10–3 to 10–7 M concentration range. High selectivity for Cu2+, Fe2+, Co2+, Mn2+, and Pb2+ was also detected. The findings of this study could have significant implications in the field of nanomaterials and environmental chemistry, particularly in the detection and removal of heavy metal ions. [ABSTRACT FROM AUTHOR]

This work presents the preparation of Ag@ Cu2O nano-crystals employing two methods, laser ablation in liquid and photo-ionization using UV radiation as a light source. The effect of Ag concentration on optical, electrical, structural, surface morphology, and other physical properties of Ag@Cu2O crystal was carried out. This work provides an on-site technique for the homogeneous development of Ag NPs on Cu2O surfaces, which involves the use of low-cost Ag salts as the source of Ag plasmonic nanoparticles. The Ag concentration was taken as a function of different chemical interaction times (5–25) sec that were used to adsorb the Ag nanoparticles (NPs) on the surface of the Cu2O sample. The optical properties ensure the improvement of the prepared material with the presence of Ag plasmonic nanoparticle, where the estimated energy gap was found to be reduced from 1.9 to 1.66 eV, and a red-shift in the optical spectra has been recognized. The surface morphology obtained by SEM images ensured the formation of a fine, smooth, uniform structure, and revealed that Ag nanoparticles have quasi-spherical morphologies with an average particle size ranging from 62 to 32 nm, based on the immersion times. Structural properties proved the formation of cubic Cu2O crystal centered at (110) diffraction plane. This was attributed to the Raman results. The optimum properties of Ag@Cu2O were obtained at 15 s, reduction of the optical band gap to 1.8 eV, and additionally, it offered the highest merit rating (F.O.M.) with an electrical conductivity of 2.09 S cm−2. [ABSTRACT FROM AUTHOR]