Pulmonary delivery of silver nanoparticles prevents influenza infection by recruiting and activating lymphoid cells.

Silver nanoparticles (AgNPs) are a potential antiviral agent due to their ability to disrupt the viral particle or alter the virus metabolism inside the host cell. In vitro, AgNPs exhibit antiviral activity against the most common human respiratory viruses. However, their capacity to modulate immune responses during respiratory viral infections has yet to be explored. This study demonstrates that administering AgNPs directly into the lungs prior to infection can reduce viral loads and therefore virus-induced cytokines in mice infected with influenza virus or murine pneumonia virus. The prophylactic effect was diminished in mice with depleted lymphoid cells. We showed that AgNPs-treatment resulted in the recruitment and activation of lymphocytes in the lungs, particularly natural killer (NK) cells. Mechanistically, AgNPs enhanced the ability of alveolar macrophages to promote both NK cell migration and IFN-γ production. By contrast, following infection, in mice treated with AgNPs, NK cells exhibited decreased activation, indicating that these nanoparticles can regulate the potentially deleterious activation of these cells. Overall, the data suggest that AgNPs may possess prophylactic antiviral properties by recruiting and controlling the activation of lymphoid cells through interaction with alveolar macrophages.

Silver-quercetin-loaded honeycomb-like Ti-based interface combats infection-triggered excessive inflammation via specific bactericidal and macrophage reprogramming.

Excessive inflammation caused by bacterial infection is the primary cause of implant failure. Antibiotic treatment often fails to prevent peri-implant infection and may induce unexpected drug resistance. Herein, a non-antibiotic strategy based on the synergy of silver ion release and macrophage reprogramming is proposed for preventing infection and bacteria-induced inflammation suppression by the organic-inorganic hybridization of silver nanoparticle (AgNP) and quercetin (Que) into a polydopamine (PDA)-based coating on the 3D framework of porous titanium (SQPdFT). Once the planktonic bacteria (e.g., Escherichia coli, Staphylococcus aureus) reach the surface of SQPdFT, released Que disrupts the bacterial membrane. Then, AgNP can penetrate the invading bacterium and kill them, which further inhibits the biofilm formation. Simultaneously, released Que can regulate macrophage polarization homeostasis via the peroxisome proliferators-activated receptors gamma (PPARγ)-mediated nuclear factor kappa-B (NF-κB) pathway, thereby terminating excessive inflammatory responses. These advantages facilitate the adhesion and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs), concomitantly suppressing osteoclast maturation, and eventually conferring superior mechanical stability to SQPdFT within the medullary cavity. In summary, owing to its excellent antibacterial effect, immune remodeling function, and pro-osteointegration ability, SQPdFT is a promising protective coating for titanium-based implants used in orthopedic replacement surgery.

Pomegranate peel mediated silver nanoparticles: antimicrobial action against crop pathogens, antioxidant potential and cytotoxicity assay.

Biologically produced silver nanoparticles are becoming a more appealing option than chemically produced antioxidants and antimicrobial agents, because they are safer, easier to manufacture and have medicinal properties at lower concentrations. In this work, we employed the aqueous pomegranate peel extract (PPE) to synthesize silver nanoparticles (PPE-AgNPs), as peel extract is a rich source of phytochemicals which functions as reducing agent for the synthesis of PPE-AgNPs. Additionally, the PPE was examined quantitatively for total phenolics and total flavonoids content. PPE-AgNPs were characterized using analytical techniques including UV-Vis spectroscopy, DLS, FTIR, XRD, HRTEM and FESEM, evaluated in vitro against the plant pathogenic microbes and also for antioxidant activities. Analytical techniques (HRTEM and FESEM) confirmed the spherical shape and XRD technique revealed the crystalline nature of synthesized PPE-AgNPs. Quantitative analysis revealed the presence of total phenolics (269.93 ± 1.01 mg GAE/g) and total flavonoids (119.70 ± 0.83 mg CE/g). Biosynthesized PPE-AgNPs exhibited significant antibacterial activity against Klebsiella aerogenes and Xanthomonas axonopodis, antifungal activity against Colletotrichum graminicola and Colletotrichum gloesporioides at 50 µg/mL concentration. The antioxidant potential of biosynthesized PPE-AgNPs was analysed via ABTS (IC50 4.25 µg/mL), DPPH (IC50 5.22 µg/mL), total antioxidant (86.68 g AAE/mL at 10 µg/mL) and FRAP (1.93 mM Fe(II)/mL at 10 µg/mL) assays. Cytotoxicity of PPE-AgNPs was valuated using MTT assay and cell viability of 83.32% was determined at 100 µg/mL concentration. These investigations suggest that synthesized PPE-AgNPs might prove useful for agricultural and medicinal purposes in the future.

Long-term effects of silver nanoparticles and mineral nutrition components on the photosynthetic processes, chloroplast ultrastructure and productivity of Solanum lycopersicum plants.

The effects of silver nanoparticles (AgNPs), both alone and in combination with mineral nutrients, on the growth and photosynthesis of Solanum lycopersicum plants during ontogeny were studied. The experiment involved weekly applications of 10 µmol of AgNPs for 15 weeks in a greenhouse over a summer period. A comprehensive characterization of the AgNPs was performed via TEM, ESI/EELS, and zeta potential measurements before and throughout the experiment. The activity of PSII, stomatal conductivity, photosynthesis, transpiration and respiration rates were measured, and the photosynthetic pigments, chloroplast ultrastructure, and dry and fresh masses of leaves, roots, and fruits were assessed. The results indicated that combining AgNPs with mineral nutrients increased PSII activity and the photosynthesis rate and altered the chloroplast ultrastructure. However, the use of mineral nutrients or AgNPs alone did not induce these changes. Atomic absorption spectrometry detected AgNPs in all the plant organs except the fruits. The highest fruit yield was associated with Veni Prisma®, a commercial product containing colloidal silver, which also caused desynchronized fruit maturation. This study hypothesizes that the synergistic effect of AgNPs and mineral nutrients enhances silver accumulation in chloroplasts, improving light utilization and photosynthetic efficiency, particularly under low light, thus increasing fruit quantity and dry mass. Conversely, long-term use of AgNPs alone was accompanied by silver accumulation outside the chloroplasts and did not lead to increased photosynthesis or an increase in fresh fruit mass.

Enhanced hydrophilicity and antibacterial efficacy of in-situ silver nanoparticles decorated Ti3C2Tx/Polylactic acid composite membrane for real hospital wastewater purification.

This study investigates the integration of Ti3C2Tx (MX) and Ag/Ti3C2Tx (Ag/MX) nanocomposites into polylactic acid membranes to enhance hydrophilicity and impart antibacterial properties, targeting hospital wastewater treatment. MX and silver nanoparticles are known for their hydrophilicity and antimicrobial capabilities, were synthesized and incorporated into PLA; a green polymer. The impact of nanocomposite concentration on the membrane's chemical structure, morphology, and overall performance were characterized using various PLA membrane properties and to evaluate the nanocomposite's performance in enhancing pure water flux and antibacterial efficacy. The pure water permeability increased from 1512 L m-2 h-1 bar-1 to 3108 L m-2 h-1 bar-1 in PLA/AgMX4 compared to PLA. Furthermore, a total bacteria count (TBC) rejection of up to 97 % was obtained using the PLA/AgMX4 membrane. The results demonstrated significant improvements in PLA/AgMX membranes compared to pristine PLA, showing a large potential for hospital wastewater treatment.

Comparative Evaluation of Antimicrobial Efficacy of Silver Nanoparticles Infused with Azadirachta indica Extract and Chlorhexidine Against Red-complex Pathogens.

AIM: The present study aimed to evaluate the antimicrobial efficacy of silver nanoparticles infused with Azadirachta indica extract and chlorhexidine against red-complex periopathogens. MATERIALS AND METHODS: Neem leaf extraction was done followed by standardization to the synthesis of neem-infused silver nanoparticles and fractionation of compounds done by using thin layer chromatography to separate the mixture of neem leaf extract. Characterization of neem-infused silver nanoparticles was done by scanning electron microscopy and UV-Visible spectroscopy. The compound identified in neem-infused silver nanoparticles was gedunin which was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Determination of antibacterial activity done by disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. Group I-99% ethanolic extract, group II-neem-infused silver nanoparticles (NAgNPs), group III-chlorhexidine. RESULTS: The relative inhibitory zone value for Tannerella forsythia (180) in neem-infused silver nanoparticles (group II) was greater when compared with other periopathogens Porphyromonas gingivalis (133) and Treponema denticola (160) than 99% ethanolic extract (group I), chlorhexidine (group III). Neem-infused silver nanoparticles (group III) showed superior antimicrobial activity against T. forsythia (19.3 ± 31.1547) and T. denticola (18±0) when compared with P. gingivalis (17.6 ± 0.5774). On evaluating MIC and minimum bacterial concentrations, P. gingivalis is more resistant than other pathogens in neem-infused silver nanoparticles (group III). CONCLUSION: Neem-infused silver nanoparticles exhibited superior antibacterial activity as compared with gold-standard chlorhexidine against red-complex periodontal pathogens. For MIC and MBC all the three periopathogens were effective but P. gingivalis was more resistant. CLINICAL SIGNIFICANCE: Antibiotics are effective against many drug-resistant bacteria. As a ready-made medicine, they can be used to treat many infections. Silver nanoparticles in drug delivery systems generally increase solubility, stability, and biodistribution, thereby increasing their effectiveness. Green synthesis using plant extracts as precursors to synthesize nanoparticles has proven to be environmentally non-hazardous combined with remarkably improved efficacy against bacterial and viral diseases. So neem-infused silver nanoparticles can be utilized as a drug delivery system. Hence, it can be used as a potential antibacterial ingredient in formulations for periodontal use like mouthwashes and gels for local drug delivery. How to cite this article: Krishnappan S, Ravindran S, Balu P, et al. Comparative Evaluation of Antimicrobial Efficacy of Silver Nanoparticles Infused with Azadirachta indica extract and Chlorhexidine Against Red-Complex Pathogens. J Contemp Dent Pract 2024;25(6):547-553.

Effect of Adding Different Concentrations of Silver Nanoparticles on Flexural Strength and Microhardness of Different Denture Base Materials.

AIM: This study aimed to evaluate the effect of adding different concentrations of silver nanoparticles (AgNPs) on the flexural strength and microhardness of various denture base materials. MATERIALS AND METHODS: For this study, a total of 60 specimens were used and divided into equal groups. The first group consisted of heat-cured acrylic resin (Vertex-Germany), while the second group consisted of thermoplastic resin (Breflex 2nd edition, Germany). The samples were created using a split brass mold with dimensions of 65 × 10 × 2.5 mm, in accordance with the specifications of the American Dental Association (specifically No. 12 for flexural and microhardness). Following this, the samples were divided into three groups (A, B, and C) based on different concentrations of AgNPs (0, 2, and 5%). The flexural and microhardness of the samples were assessed using a universal testing machine and the Vickers hardness test, respectively. The data were gathered, organized, and analyzed using statistical methods. RESULTS: The flexural strength findings showed a significant difference between the two groups. Also, there was a considerable decrease in the average value of the acrylic group as the concentrations of AgNPs rose, while the flexural strength of the thermoplastic group notably improved. Regarding microhardness, the results showed a significant difference between the two groups. It showed that the mean value of both groups increased with increasing concentrations of AgNPs. CONCLUSION: Within the limitations of laboratory testing conditions of this study, it was discovered that AgNPs negatively impact the flexural strength of acrylic resins. Furthermore, an increase in the concentration of AgNPs was found to be directly related to the flexural strength of thermoplastic resin and the microhardness of both groups. CLINICAL SIGNIFICANCE: The concentration of AgNPs has a significant impact on certain mechanical properties of denture base materials, but it is important to consider their potential toxicity. How to cite this article: El-Hussein IG. Effect of Adding Different Concentrations of Silver Nanoparticles on Flexural Strength and Microhardness of Different Denture Base Materials. J Contemp Dent Pract 2024;25(5):417-423.

Bactericidal, anti-hemolytic, and anticancerous activities of phytofabricated silver nanoparticles of glycine max seeds.

Introduction: Soybean is a rich source of bioactive components with good nutritional support and is easily available. In the treatment of cancer, green synthesis of silver nanoparticles (AgNPs) from plant-based samples has gained attentions due to its potency and feasibility. In the present study, using soybean extracts (GM), silver nanoparticles are synthesized and analyzed for their anticancer potency. Methods: The synthesized GM-AgNPs were characterized via UV-Vis spectroscopy, Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) techniques for further analysis. Antibacterial activity was evaluated using the disc method and anti-hemolysis activity using the in vitro method, followed by anticancer property evaluation by cytotoxicity, cell migration, apoptosis, and cell cycle. Results and discussion: Our results showed that the synthesized GM-AgNPs were spiral-shaped with a size range of 5-50 nm. The antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae showed the maximum zone of inhibition at 250 µg/mL in comparison with gentamicin. On exploring the anti-hemolysis efficiency, at 200 µg/mL, GM-AgNPs showed no hemolysis in comparison to the extract which showed 40% hemolysis. On analysis of GM-AgNPs against the breast cancer cell line, the nanoparticles displayed the IC50 value of 74.04 µg/mL. Furthermore, at the IC50 concentration, cancer cell migration was reduced. The mechanism of action of GM-AgNPs confirmed the initiation of apoptosis and cell cycle arrest in the sub-G0/G1 (growth phase) phase by 48.19%. In gene expression and protein expression analyses, Bax and Bcl-2 were altered to those of normal physiology.

Ceramic Filters Coated with Green Ag-Nanoparticles for Drinking Water Treatment in Rural Households of Nigeria.

A ceramic water filter (CWF) coated with plant-based nanoparticles was used as household water purifier in a rural community. Silver nanoparticles (AgNPs) were produced from the stem bark of Bridelia ferruginea plant, and their efficacy to enhance the physical, chemical, and microbial quality of raw stream water sample was determined using analytical probes and pour-plate techniques, respectively. The pH of the filtered water sample ranged 7.6 to 8.1, which is within the WHO permissible limit for drinking water, and the electrical conductivity values were also reduced from 110 to 70 µS/cm. The CWF coated with AgNPs (CWF-AgNPs) removed Klebsiella pnuemoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Entamoeba histolytica from the stream water sample. The highest percentage of coliform reduction in the CWF and CWF-AgNPs were 93.18% and 99.64%, respectively. The raw data showed that the CWF-NPs enhanced the quality of the stream water. The surface and internal structure of the CWF-AgNPs can be modified by varying the concentration of the composite materials, so as to determine the most effective combination. The improved CWF-AgNPs will enhance achieving United Nations Sustainable Development Goal #6, which focuses on clean water and sanitation.

Ceramic water filter (CWF) coated with the stem-bark of Bridelia ferruginea plant was used as household water purifier in a rural community. The efficacy to enhance the physical, chemical, and microbial quality of raw stream water sample was determined using standard methods. The CWF improve the quality of the tested water and removed bacteria from the water samples. The CWF can be used for water treatment in rural households, as this will enhance achieving the United Nations Sustainable Development Goal #6, which focuses on clean water and sanitation.

An Overview of the Anticancer Potential of Silver Nanostructures against Cervical Cancer.

Women are impacted by the extremely common cancer known as cervical cancer worldwide. Although preventive vaccines for cervical cancer are successful, treatment of cervical cancer is far less satisfactory because of multidrug resistance and side effects. There is an increasing need for alternative treatment modalities due to the rather aggressive and non-specific nature of conventional chemotherapeutics. With the advent of new technologies, scientists are working harder to create novel drug delivery strategies for chemotherapy of cervical cancer. Metal nanoparticles, and particularly silver nanoparticles, are a relatively new class with a lot of promise in the field of cancer biology. Nanoparticle therapeutics are attractive platforms for clinically relevant drug development because of their powerful anti-cancer properties, correspondingly attenuated side effects, and cancer-specific targeting. In this review, we provide an overview of the most recent uses of nanotechnology, particularly silver nanostructures, in the diagnosis and treatment of cervical cancer. The salient features of silver nanoparticle-based therapeutic concepts that are novel, viable, and attainable are emphasized in this review, along with those that pose a significant obstacle to their progress toward clinical application.

Synergistic inhibition effect of diolefinic dye and silver nanoparticles for carbon steel corrosion in hydrochloric acid solution.

The current work looks at the inhibitory effects of a diolefinic dye, namely 1,4-bis((E)-2-(3-methyl-2,3-dihydrobenzo[d]thiazol-2-yl) vinyl) benzene iodide salt, in relation to CS corrosion mitigation in hydrochloric acid (HCl) environment. This study uses a variety of experimental methodologies, including weight loss (WL) analysis, electrochemical tests, and theoretical considerations. The synergistic effect of diolefinic dye and AgNPs on the corrosion inhibition of CS in 1 M HCl was investigated. The inhibition efficiency (IE) displays a notable enhancement as the concentration of the dye is elevated and as the temperature raises the IE increases. The diolefinic dye exhibited % IE of 83% even at low concentration (1 × 10-4 M) whereas 90% in the presence of (2.26 × 10-10) AgNPs. Tafel graphs demonstrate that the dye follows a mixed type inhibitor. The adsorption of the dye on CS surface follows Langmuir model. Moreover, the influence of temperature and the activation parameters disclose that diolefinic dye is chemisorbed on the CS surface. The synergistic coefficient of the diolefinic dye and AgNPs under various concentration conditions was greater than unity. The surface morphology of CS sheets was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Density Functional Theory (DFT) calculations provide theoretical support for the inhibitory effects of the examined dye. Notably, there is a high agreement between the findings of practical studies and theoretical expectations.

Dose-dependent effects of silver nanoparticles on cell death modes in mouse blastocysts induced via endoplasmic reticulum stress and mitochondrial apoptosis.

In view of the rapidly expanding medical and commercial applications of silver nanoparticles (AgNPs), their potential health risks and environmental effects are a significant growing concern. Earlier research by our group uncovered the embryotoxic potential of AgNPs, showing detrimental impacts of these nanoparticles on both pre- and post-implantation embryonic development. In the current study, we showed that low (50-100 µM) and high (200-400 µM) dose ranges of AgNPs trigger distinct cell death programs affecting mouse embryo development and further explored the underlying mechanisms. Treatment with low concentrations of AgNPs (50-100 µM) triggered ROS generation, in turn, inducing mitochondria-dependent apoptosis, and ultimately, harmful effects on embryo implantation, post-implantation development, and fetal development. Notably, high concentrations of AgNPs (200-400 µM) evoked more high-level ROS generation and endoplasmic reticulum (ER) stress-mediated necrosis. Interestingly, pre-incubation with Trolox, a strong antioxidant, reduced ROS generation in the group treated with 200-400 µM AgNPs to the level induced by 50-100 µM AgNPs, resulting in switching of the cell death mode from necrosis to apoptosis and a significant improvement in the impairment of embryonic development. Our findings additionally indicate that activation of PAK2 is a crucial step in AgNP-triggered apoptosis and sequent detrimental effects on embryonic development. Based on the collective results, we propose that the levels of ROS generated by AgNP treatment of embryos serve as a critical regulator of cell death type, leading to differential degrees of damage to embryo implantation, post-implantation development and fetal development through triggering apoptosis, necrosis or other cell death signaling cascades.

Nanotechnology in action: silver nanoparticles for improved eco-friendly remediation.

Nanotechnology is an exciting area with great potential for use in biotechnology due to the far-reaching effects of nanoscale materials and their size-dependent characteristics. Silver and other metal nanoparticles have attracted a lot of attention lately because of the exceptional optical, electrical, and antimicrobial characteristics they possess. Silver nanoparticles (AgNPs) stand out due to their cost-effectiveness and abundant presence in the earth's crust, making them a compelling subject for further exploration. The vital efficacy of silver nanoparticles in addressing environmental concerns is emphasized in this thorough overview that dives into their significance in environmental remediation. Leveraging the distinctive properties of AgNPs, such as their antibacterial and catalytic characteristics, innovative solutions for efficient treatment of pollutants are being developed. The review critically examines the transformative potential of silver nanoparticles, exploring their various applications and promising achievements in enhancing environmental remediation techniques. As environmental defenders, this study advocates for intensified investigation and application of silver nanoparticles. Furthermore, this review aims to assist future investigators in developing more cost-effective and efficient innovations involving AgNPs carrying nanoprobes. These nanoprobes have the potential to detect numerous groups of contaminants simultaneously, with a low limit of detection (LOD) and reliable reproducibility. The goal is to utilize these innovations for environmental remediation purposes.

Manipulating Silver Nanoparticles with Biomolecular Corona Secreted from Vertebrates to Improve the Loading Capacity and Biocompatibility.

Silver nanoparticles (AgNPs) are widely used as nanoagents in biomedical fields, while it is still challenging to improve their loading capacity and biocompatibility in microcarrier delivering systems. Herein, the physicochemical properties of AgNPs were manipulated by forming biomolecular corona derived from bovine serum albumin (AC), and three organisms at various trophic levels: Chlorella sp. (BC1), Daphnia magna (BC2), and zebrafish (BC3). Proteins were identified by chemical composition analysis as the dominant components adsorbed on the surface of AgNPs. Proteomics indicated that AgNPs preferred to bind with low molecular weight (<50 kDa) and hydrophobic proteins with more positively charged residues. Consequently, AC and BC3 displayed stronger adsorption affinity on the surface of AgNPs than BC1 and BC2. Modifications by AC and BC3 effectively alleviated the oxidative stress and cell cycle arrest of AgNPs due to their superior antioxidative ability. However, BC3 with lower hydrophobicity enabled AgNPs to be more biocompatible than AC at subcellular level. Moreover, AC could significantly improve the loading capacity of AgNPs by Chlorella through enhancing caveolin-mediated endocytosis. Notably, owing to the adsorption of abundant Ca2+-binding proteins, BC3-AgNPs could also be internalized by microalgae via Ca2+-dependent clathrin-mediated endocytosis, which makes it a promising approach to deliver AgNPs. The results of this study would provide insights into the development of an efficient strategy to deliver AgNPs based on the microalgae carrier without altering its original properties and functionality.

Soft surface-enhanced Raman scattering sensing platform based on an oil-in-water emulsion stabilized by silver nanoparticles.

Pickering emulsions are excellent candidates for developing soft biosensors utilized for detecting native biomolecules such as peptides and proteins through the Surface-Enhanced Raman Spectroscopy (SERS) transduction mechanism. Here, we have developed a SERS sensor based on oil-in-water Pickering emulsions stabilized by Ag nanoparticles (Ag-NPs) with the Raman active molecule (4-Aminothiphenol, 4ATP) adsorbed to their surface. The structural properties and composition of the Pickering emulsion were tuned to meet the demands of the maximal optical response. Our results show that the obtained SERS signals of the main studied Pickering emulsion (water: oil ratio 7:3, 1 wt% Ag-NPs) outperformed colloidal dispersions with the same Ag-NPs concentration by 10-fold at any studied content of 4ATP. The superior optical response of the Pickering emulsion compared to the colloidal dispersion can thus pave the way for the detection of a large variety of analytes at high sensitivity by a soft sensing device. This study innovates by comparing the SERS signals of Raman-active Ag-NPs when they are assembled at the oil/water interface of an emulsion to the case where the NPs are individually dispersed in the medium. The findings shed light on the edit value of utilizing Raman-active Pickering stabilizers for biosensing applications.

Evaluation of extraction and storage conditions for quantification and characterization of silver nanoparticles in complex samples by single particle-ICP-MS.

The extraction of nanoparticles (NPs) from complex matrices and subsequent storage can potentially alter the NPs physicochemical properties and hinder cross-study comparisons. Most NP extraction methods are designed and tested at high nanoparticle concentrations, although (eco)toxicological and regulatory monitoring programs require methods capable of analyzing NPs at environmentally relevant concentrations (lower ppb range). In this study, we investigated how extraction methods affect the characteristics of PVP coated and citrate-stabilized silver NPs (AgNPs) spiked into soil, sewage sludge, and biological samples at environmentally relevant concentrations using Single Particle Inductively Coupled Plasma Mass Spectrometry spICP-MS). Further we investigated the impact of storage temperature (-80°C to 21°C) and storage duration (1-28 days) on the particle characteristics such as particle size. We found that aqueous AgNPs samples with low ionic strength media retained their original characteristics (like particle size, particle concentration and particle-based Ag mass) when preserved at 4°C for up to 28 days. AgNPs dispersed in high ionic strength media were however better preserved at -80°C. Among the extraction agents, tetrasodium pyrophosphate was more efficient in extracting AgNPs from soil and sewage sludge matrices, while Proteinase K was more suitable for biological samples from organisms (earthworms or fish). Although our study focused only on AgNPs, it provides crucial information to aid interlaboratory comparisons and data interpretation for (eco)toxicological studies.

SERS activity of silver nanoparticles and silver-modified 2D graphitic carbon nitride towards ciprofloxacin drug.

Herein, silver nanoparticles (AgNPs) and silver-loaded graphitic carbon nitride (Ag@g-C3N4) nanocomposites have been synthesized and used as an effective surface-enhanced Raman scattering (SERS) substrates for the detection of low concentrations (10-14 M) of ciprofloxacin (CIP), a commonly bioactive medication used to treat bacterial illnesses. A combined approach of vibrational spectroscopy and density functional theory (DFT) has been developed to understand the possible modes of analyte (CIP) and SERS substrate (AgNPs and Ag@g-C3N4) interactions. Furthermore, it has been noticed that the behavior of drug molecules in terms of SERS response and energetics of interaction changed significantly when interacted with the noble metal AgNPs decorated onto the g-C3N4 framework in comparison to only AgNPs as substrate. The most prominent interaction scenario between AgNPs and CIP is likely to be through the -NH moiety of drug molecule with an interaction energy of -306 kcal/mol. Whereas, the CIP molecules adsorbed onto Ag@g-C3N4 nanocomposite were more flexible with interaction energy of -107 kcal/mol, suggesting a greater association of analyte with the skeletal modes of substrate leading to Raman enhancements in the low wavenumber region i.e. below 600 cm-1. Hence, the Ag@g-C3N4 nanocomposite-based SERS substrates investigated served two distinct spectral ranges, making them complementary of each other in terms of SERS detection of CIP. The characteristics of the computed frontier molecular orbitals indicated a pronounced amount of charge transfer between the drug and the substrate, highlighting the significance of the chemical mechanism of the overall process. These results represent a successful approach to have an extended spectral range that covers lower wavenumber shifts by applying simple and meaningful modifications to the normally utilized noble metal-based nanoparticles, which can lead to more effective and reliable detection of bioactive drugs.

Optical and Chiroptical Stimuli-Responsive Chiral AgNPs@H-Leu-Poly(phenylacetylene) Nanocomposites in Water.

Dynamic macroscopically chiral nanocomposites are prepared by combining silver nanoparticles (AgNPs) and dynamic helical poly(phenylacetylene)s (PPAs) bearing pendants functionalized with amino groups. These amino groups provide the nanocomposite with the ability to disperse in water along with high stability due to the interaction between the ammonium group and the AgNP. Moreover, the equilibrium between NH3+/NH2 produces a "blinking" contact between the PPA and the AgNPs, which allows total control of the dynamic helical behavior of the polymer. The use of acidic or neutral pH allows controlling the morphology of the nanocomposite, which consists of a nanosphere that has trapped inside it a single AgNP (pH = 2) or several AgNPs (pH = 7) with ca. 30 nm of diameter. These nanocomposites combine the optical and chiroptical stimuli-responsive properties of both components, AgNPs and PPAs. Thus, the controlled aggregation of the nanocomposite produced variations in the LSPR band of the AgNPs in a reversible manner. In turn, given that the chiral coating is selective to Ba2+, the presence of this metal ion caused a helical inversion of the chiral coating of the nanocomposite detected by electronic circular dichroism. Moreover, it is possible to distinguish between three metal ions in different oxidation states, such as Ce4+, Fe3+, and Hg2+, which produce different responses of the nanocomposite when oxidizing the AgNP to Ag+.

Long-Term Effectiveness of Engineered T7 Phages Armed with Silver Nanoparticles Against Escherichia coli Biofilm.

The escalating threat of antibiotic-resistant bacteria, particularly those forming biofilm structures, underscores the urgent need for alternative treatment strategies. Bacteriophages have emerged as promising agents for combating bacterial infections, especially those associated with biofilm formation. However, the efficacy of phage therapy can be limited by the development of bacterial resistance and biofilm regrowth. Interestingly, phages could be combined with other agents, such as metal nanoparticles, to enhance their antibacterial effectiveness. Since the therapeutic strategy of using phages and metal nanoparticles has been developed relatively recently, evaluating its efficacy under various conditions is essential, with a particular focus on the duration of activity. This study tested the hypothesis that a novel approach to combating bacterial biofilms, based on phages armed with silver nanoparticles (AgNPs), would exhibit enhanced activity over an extended period after application. In this work, we investigated the potential of engineered T7 phages armed with AgNPs for eradicating Escherichia coli biofilm. We demonstrated that such biomaterial exhibits sustained antimicrobial activity even after prolonged exposure. Compared to phages alone or AgNPs alone, the biomaterial significantly enhances biofilm eradication, particularly after 48 hours of treatment. These findings highlight the potential of synergistic phage-nanoparticle strategies for combatting biofilm-associated infections.

Microbiological evaluation of vitamin C rich acerola mediated silver and copperoxide nanogel in treatment of periodontitis with and without diabetes mellitus.

Aim: Nanotechnology presents a promising approach for managing chronic periodontitis, a common oral disease characterized by gum inflammation and loss of supporting bone around teeth. This study aimed to evaluate the antimicrobial efficacy of acerola-mediated silver nanoparticles (AgNPs) gel and copper oxide nanoparticles (CuONPs) gel in periodontitis patients with and without diabetes. Materials and methods: The antimicrobial efficacy of acerola-mediated AgNPs gel and CuONPs nanogel was assessed using the agar well diffusion technique, Minimum Inhibitory Concentration (MIC) assay, Minimum Bactericidal Concentration (MBC) analysis, time-kill curve assay, and cytoplasmic and protein leakage analysis from periodontitis patients with and without diabetes. Results: The study found that acerola-mediated AgNPs gel demonstrated more consistent and effective antimicrobial activity against periodontitis, with lower MIC and MBC values compared to the CuONPs gel, across all tested concentrations. These results suggest that acerola-mediated AgNPs gel may be a more effective and targeted therapeutic agent for periodontal disease management. Conclusion: The findings emphasize the importance of nanoparticle gel concentration in optimizing periodontal treatment outcomes. Acerola-mediated AgNPs gel, with its superior efficacy and consistency in bactericidal activity, shows significant potential for periodontal therapy. Clinical significance: Innovative nanoparticles like copper and silver oxides exhibit antibacterial, anti-inflammatory, and antioxidant properties, making them promising agents for targeting periodontal pathogens. Acerola (Malpighia emarginata), with its high vitamin C content and antioxidant properties, is beneficial in mitigating oxidative stress associated with chronic periodontitis.