Broad-spectrum bioactivities of silver nanoparticles: the emerging trends and future prospects

Unlocking the Potential of Silver Nanoparticles: From Synthesis to Versatile Bio-Applications

Silver nanoparticles (AgNPs) are leading the way in nanotechnological innovation, combining the captivating properties of silver with the accuracy of nanoscale engineering, thus revolutionizing material science. Three main techniques arise within the alchemical domains of AgNP genesis: chemical, physical, and biological synthesis. Each possesses its distinct form of magic for controlling size, shape, and scalability-key factors necessary for achieving expertise in the practical application of nanoparticles. The story unravels, describing the careful coordination of chemical reduction, the environmentally sensitive charm of green synthesis utilizing plant extracts, and the precise accuracy of physical techniques. AgNPs are highly praised in the field of healthcare for their powerful antibacterial characteristics. These little warriors display a wide-ranging attack against bacteria, fungi, parasites, and viruses. Their critical significance in combating hospital-acquired and surgical site infections is highly praised, serving as a beacon of hope in the fight against the challenging problem of antibiotic resistance. In addition to their ability to kill bacteria, AgNPs are also known to promote tissue regeneration and facilitate wound healing. The field of cancer has also observed the adaptability of AgNPs. The review documents their role as innovative carriers of drugs, specifically designed to target cancer cells with accuracy, minimizing harm to healthy tissues. Additionally, it explores their potential as cancer therapy or anticancer agents capable of disrupting the growth of tumors. In the food business, AgNPs are utilized to enhance the durability of packing materials and coatings by infusing them with their bactericidal properties. This results in improved food safety measures and a significant increase in the duration that products can be stored, thereby tackling the crucial issue of food preservation. This academic analysis recognizes the many difficulties that come with the creation and incorporation of AgNPs. This statement pertains to the evaluation of environmental factors and the effort to enhance synthetic processes. The review predicts future academic pursuits, envisioning progress that will enhance the usefulness of AgNPs and increase their importance from being new to becoming essential within the realms of science and industry. Besides, AgNPs are not only a subject of scholarly interest but also a crucial component in the continuous effort to tackle some of the most urgent health and conservation concerns of contemporary society. This review aims to explore the complex process of AgNP synthesis and highlight their numerous uses, with a special focus on their growing importance in the healthcare and food business sectors. This review invites the scientific community to explore the extensive possibilities of AgNPs in order to fully understand and utilize their potential.

Optimization of Rhizoclonium hieroglyphicum extract for enhanced synthesis of nickel oxide nanoparticles using response surface methodology and its potential exploration in biological application

The study investigates the potential of Rhizoclonium hieroglyphicum as a novel source for synthesizing nickel oxide nanoparticles (RH-NiONPs) and evaluates its biological applications. Phytochemicals in the algal extract serve as capping, reducing and stabilizing agent for nickel oxide nanoparticles. The process variables were optimized using BBD based RSM to obtain maximum RH-NiONPs. Characterization of RH-NiONPs using UV-Vis and FT-IR spectroscopy reveals the plasmon resonance peak at 340 nm and the functional groups responsible for reduction and stabilization. XRD confirmed the crystalline nature while the stability and size of the RH-NiONPs were determined by DLS and zeta potential. Toxicity assessments demonstrated the effect of RH-NiONPs against Vigna radiata, Allium cepa and Artemia salina was low. RH-NiONPs revealed significant zone of inhibition against the selected bacteria and fungi. The results of larvicidal activity showed that RH-NiONPs are toxic to 4th instar larvae of Daphnis nerii. Also, RH-NiONPs efficiently decolorized Reactive Violet 13 (92%) under sunlight irradiation and the experimental data well fits to Langmuir isotherm along with pseudo second order kinetic model. The thermodynamic studies enunciate the exothermic and non-spontaneous photocatalytic decolorization of reactive violet 13. Thus, the current study assesses the eco-friendly and cost-effective nature of RH-NiONPs along with its biological applications.

Green synthesized silver nanoparticles from Phoenix dactylifera synergistically interact with bioactive extract of Punica granatum against bacterial virulence and biofilm development

The global rise of antibiotic resistance poses a substantial risk to mankind, underscoring the necessity for alternative antimicrobial options. Developing novel drugs has become challenging in matching the pace at which microbial resistance is evolving. Recently, nanotechnology, coupled with natural compounds, has emerged as a promising solution to combat multidrug-resistant bacteria. In the present study, silver nanoparticles were green-synthesized using aqueous extract of Phoenix dactylifera (variety Ajwa) fruits and characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and Thermogravimetric-differential thermal analysis (TGA-DTA). The in-vitro synergy of green synthesized P. dactylifera silver nanoparticle (PD-AgNPs) with selected antibiotics and bioactive extract of Punica granatum, i.e., ethyl acetate fraction (PGEF), was investigated using checkerboard assays. The most effective synergistic combination was evaluated against the QS-regulated virulence factors production and biofilm of Pseudomonas aeruginosa PAO1 by spectroscopic assays and electron microscopy. In-vivo anti-infective efficacy was examined in Caenorhabditis elegans N2 worms. PD-AgNPs were characterized as spherical in shape with an average diameter of 28.9 nm. FTIR analysis revealed the presence of functional groups responsible for the decrease and stabilization of PD-AgNPs. The signals produced by TGA-DTA analysis indicated the generation of thermally stable and pure crystallite AgNPs. Key phytocompounds detected in bioactive fractions include gulonic acid, dihydrocaffeic acid 3-O-glucuronide, and various fatty acids. The MIC of PD-AgNPs and PGEF ranged from 32 to 128 μg/mL and 250-500 μg/mL, respectively, against test bacterial strains. In-vitro, PD-AgNPs showed additive interaction with selected antibiotics (FICI 0.625-0.75) and synergy with PGEF (FICI 0.25-0.375). This combination inhibited virulence factors by up to 75 % and biofilm formation by 84.87 % in P. aeruginosa PAO1. Infected C. elegans worms with P. aeruginosa PAO1 had a 92.55 % survival rate when treated with PD-AgNPs and PGEF. The combination also reduced the reactive oxygen species (ROS) level in C. elegans N2 compared to the untreated control. Overall, these findings highlight that biosynthesized PD-AgNPs and bioactive P. granatum extract may be used as a potential therapeutic formulation against MDR bacteria.

Application of green synthesized Ag and Cu nanoparticles for the control of bruchids and their impact on seed quality and yield in greengram

Storage pests, particularly bruchids, are major biotic constraints causing significant storage losses in pulses. Conventional control methods relying on insecticides and fumigants often lead to food contamination due to toxic pesticide residues and a rapid decline in seed germination. In this investigation, through green nano-technological application, a promising and sustainable alternative for pest management is developed. Silver and copper nanoparticles were synthesized through ocimum leaf extract. The characterization of silver and copper nanoparticles was carried out by UV-spectroscopy, particle size analyzer, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared. Both the nanoparticles were spherical and crystalline in nature. Greengram seeds were primed with standardized silver and copper nanoparticles at different concentrations (1000, 1500, and 2000 ppm) and compared with castor-treated, deltamethrin-treated, and untreated control seeds for seed quality, growth, and yield. After one month of storage, all the pulse beetles released in different treatments exhibited 100 % mortality, whereas in control, the insects multiplied. At the end of nine months, the control seeds had shown 72 % damage and 39.67 % germination. In contrast, silver nanoparticles at 1000 ppm showed no seed damage and achieved 81.67 % germination, which was on par with copper nanoparticles at 1000 ppm with 79.33 % germination. Seed priming of silver and copper nanoparticles at 1000 ppm also demonstrated superior performance in all the seed quality and biochemical parameters (alpha amylase and catalase) throughout the storage period. Whereas, in the greenhouse experiment, enhanced growth (35.96 cm, 46.48 cm, and 53.00 cm at 30, 60 DAS, and at harvest, respectively) and yield per plant (3.75 g) were significantly higher in plants that were given foliar application with silver nanoparticles at 1000 ppm. Furthermore, foliar application of these nanoparticles at all concentrations (1000, 1500, and 2000 ppm) did not exhibit any adverse effects on soil microbial organisms, as assessed by dehydrogenase enzyme activity. Hence, this research highlights the potential use of silver and copper nanoparticles at 1000 ppm as effective tools for storage pest management and contributing to improved agricultural productivity and sustainability.

"Therapeutic advancements in nanomedicine: The multifaceted roles of silver nanoparticles"

Nanotechnology has the advantages of enhanced bioactivity, reduced toxicity, target specificity, and sustained release and NPs can penetrate cell membranes. The small size of silver nanoparticles, AgNPs, large surface area, and unique physicochemical properties contribute to cell lysis and increased permeability of cell membranes used in the field of biomedicine. Functional precursors integrate with phytochemicals to create distinctive therapeutic properties and the stability of the nanoparticles can be enhanced by Surface coatings and encapsulation methods, The current study explores the various synthesis methods and characterization techniques of silver nanoparticles (AgNPs) and highlights their intrinsic activity in therapeutic applications, Anti-cancer activity noted at a concentration range of 5-50 μg/ml and angiogenesis is mitigated at a dosage range of 10-50 μg/ml, Diabetes is controlled within the same concentration. Wound healing is improved at concentrations of 10-50 μg/ml and with a typical range of 10-08 μg/ml for bacteria with antimicrobial capabilities. Advancement of silver nanoparticles with a focus on the future use of AgNPs-coated wound dressings and medical devices to decrease the risk of infection. Chemotherapeutic drugs can be administered by AgNPs, which reduces adverse effects and an improvement in treatment outcomes. AgNPs have been found to improve cell proliferation and differentiation, making them beneficial for tissue engineering and regenerative medicine. Our study highlights emerging patterns and developments in the field of medicine, inferring potential future paths.

Exploring sustainable management by using green nano-silver to combat three post-harvest pathogenic fungi in crops

Global crop protection and food security have become critical issues to achieve the 'Zero Hunger' goal in recent years, as significant crop damage is primarily caused by biotic factors. Applying nanoparticles in agriculture could enhance crop yield. Nano-silver, or AgNPs, have colossal importance in many fields like biomedical, agriculture, and the environment due to their antimicrobial potential. In this context, nano-silver was fabricated by Citrus medica L. (Cm) fruit juice, detected visually and by UV-Vis spectrophotometric analysis. Further, AgNPs were characterized by advanced techniques. UV-Vis spectroscopic analysis revealed absorbance spectra at around 487 nm. The zeta potential measurement value was noted as -23.7 mV. Spectral analysis by FT-IR proved the capping of the acidic groups. In contrast, the XRD analysis showed the Miller indices like the face-centered cubic (fcc) crystalline structure. NTA revealed a mean size of 35 nm for nano-silver with a 2.4 × 108 particles mL-1 concentration. TEM analysis demonstrated spherical Cm-AgNPs with 20-30 nm sizes. The focus of this research was to evaluate the antifungal activity of biogenic AgNPs against post-harvest pathogenic fungi, including Aspergillus niger, A. flavus, and Alternaria alternata. The Cm-AgNPs showed significant antifungal activity in the order of A. niger > A. flavus > A. alternata. The biogenic Cm-AgNPs can be used for the inhibition of toxigenic fungi.

Açaí (Euterpe oleracea Mart.) green synthesis of silver nanoparticles: antimicrobial efficacy and ecotoxicological assessment

The synthesis of silver nanoparticles (AgNPs) is usually based on expensive methods that use or generate chemicals that can negatively impact the environment. Our study presents a simple one-step synthesis process for obtaining AgNP using an aqueous extract of Amazonian fruit açai (Euterpe oleracea Mart.) as the reducing and stabilizing agents. The bio-synthesized AgNP (bio-AgNP) were comprehensively characterized by diverse techniques, and as a result, 20-nm spherical particles (transmission electron microscopy) were obtained. X-ray diffraction analysis (XRD) confirmed the presence of crystalline AgNP, and Fourier-transform infrared spectroscopy (FT-IR) suggested that polyphenolic compounds of açaí were present on the surface. The bio-AgNP showed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii. In Caenorhabditis elegans exposed to 10 μg/L bio-AgNP for 96 h, there were no significant effects on growth, reproduction, or reactive oxygen species (ROS) concentration; however, there was an increase in superoxide dismutase (SOD) and glutathione-S-transferase (GST) enzymatic activity. In contrast, when worms were exposed to chemically synthesized AgNP (PVP-AgNP), an increase in ROS, SOD, and GST activity and a reduction in oxidative stress resistance were observed. In conclusion, our study not only showcased the potential of açaí in the simple and rapid production of AgNP but also highlighted the broad-spectrum antimicrobial activity of the synthesized nanoparticles using our protocol. Moreover, our findings revealed that these AgNPs exhibited reduced toxicity to C. elegans at environmentally realistic concentrations compared with PVP-AgNP.

4-Nitrophenol reduction and antibacterial activity of Ag-doped TiO2 photocatalysts

Water contamination by organic pollutants is a serious environmental problem. 4-Nitrophenol (4-NP) is a potentially harmful chemical, which is commonly present in industrial effluents and can severely damage human health. Photocatalytic reduction of hazardous 4-NP by nano-sized materials to produce 4-aminophenol (4-AP), which is a commercially valuable product, is a promising alternative as the process is framed within the circular economy. In this context, Ag-doped TiO2 (AT) catalysts were synthesized by liquid impregnation and reduction techniques, and their structure, morphology, elemental composition, textural, and light absorption properties were evaluated by XRD, Raman spectroscopy, SEM, TEM, EDS, BET, and DRS spectroscopy. AT catalysts exhibited an enhanced photocatalytic reduction of 4-NP into 4-aminophenol (4-AP) in the presence of NaBH4. Among the tested catalysts, AT21 prepared by a simple aqueous reduction method showed the highest activity reaching about 98% 4-NP reduction within 10 min. Antibacterial tests of these catalysts against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa revealed that AT21 also exhibited the lowest minimum inhibitory concentration, suggesting that it has the strongest antibacterial activity. These findings suggest that AT21 catalyst with improved catalytic and antibacterial properties can potentially be utilized for the remediation of 4-NP-contaminated water environment.

An overview of green synthesized silver nanoparticles towards bioactive antibacterial, antimicrobial and antifungal applications

Present review emphatically introduces the synthesis, biocompatibility, and applications of silver nanoparticles (AgNPs), including their antibacterial, antimicrobial, and antifungal properties. A comprehensive discussion of various synthesis methods for AgNPs, with a particular focus on green chemistry mediated by plant extracts has been made. Recent research has revealed that the optical properties of AgNPs, including surface plasmon resonance (SPR), depend on the particle size, as well as the synthesis methods, preparation synthesis parameters, and used reducing agents. The significant emphasis on the use of synthesized AgNPs as antibacterial, antimicrobial, and antifungal agents in various applications has been reviewed. Furthermore, the application areas have been thoroughly examined, providing a detailed discussion of the underlying mechanisms, which aids in determining the optimal control parameters during the synthesis process of AgNPs. Furthermore, the challenges encountered while utilizing AgNPs and the corresponding advancements to overcome them have also been addressed. This review not only summarizes the achievements and current status of plant-mediated green synthesis of AgNPs but also explores the future prospects of these materials and technology in diverse areas, including bioactive applications.

Silver nanoparticle as an alternate to antibiotics in cattle semen during cryopreservation

The proposed study was to determine if the silver nanoparticles can be used as potential antimicrobial agents and can replace the use of conventional antibiotics in semen without affecting the motility and fertility of semen. The silver nanoparticles prepared by chemical reduction method were confirmed by determination of the wavelength of surface plasmon resonance peak and further characterized using Zetasizer by determining their size, polydispersity index, and zeta potential. The nanoparticles were assessed for antibacterial activity and their concentration was optimized for use in semen extender for cryopreservation. Cryopreserved semen was further evaluated for seminal parameters, antioxidant parameter, and microbial load. Prepared silver NPs showed a plasmon resonance peak at 417 nm wavelength. NPs were found to possess antibacterial activity and were supplemented in semen extender @ 125 and 250 µg/ml for semen cryopreservation. There was a significant increase in pre and post-freezing motility and other seminal parameters. The microbial load of frozen-thawed semen of control and supplemented groups were well within the permissible limits. Lipid peroxidation levels were reduced in NPs supplemented groups, and reactive oxygen species (ROS) levels were significantly reduced in semen supplemented with 125 µg/ml NPs. Thus it can be conclude that silver NPs can be successfully used as a substitute for antibiotics in cattle bull semen cryopreservation with good antimicrobial activity and no adverse effects on sperm characteristics.

Applications of Silver Nanoparticles in Dentistry

Silver nanoparticles (AgNPs) have been effectively applicable in most regions because of their antimicrobial activity against various microorganisms. AgNPs can be applied in disinfection and prophylaxis and to prevent diseases of the oral cavity. Because of developing interest in AgNPs, this article shows the application of AgNPs in various fields of dentistry such as nanocomposites, implant coatings, inhibiting the growth of bacteria, preventing dental caries, biofilm, infectious microbes, local anesthesia, microorganisms causing damage to the pulp, as well as deals with diseases such as oral malignancies due to their antitumor properties. AgNPs have a potential system with major features including antibacterial, anti-inflammatory, and anticancer action. They may also be used as a sustained drug delivery vehicle.

Reports of Plant-Derived Nanoparticles for Prostate Cancer Therapy

Plants have demonstrated potential in providing various types of phytomedicines with chemopreventive properties that can combat prostate cancer. However, despite their promising in vitro activity, the incorporation of these phytochemicals into the market as anticancer agents has been hindered by their poor bioavailability, mainly due to their inadequate aqueous solubility, chemical instability, and unsatisfactory circulation time. To overcome these drawbacks, it has been suggested that the incorporation of phytochemicals as nanoparticles can offer a solution. The use of plant-based chemicals can also improve the biocompatibility of the formulated nanoparticles by avoiding the use of certain hazardous chemicals in the synthesis, leading to decreased toxicity in vivo. Moreover, in some cases, phytochemicals can act as targeting agents to tumour sites. This review will focus on and summarize the following points: the different types of nanoparticles that contain individual phytochemicals or plant extracts in their design with the aim of improving the bioavailability of the phytochemicals; the therapeutic evaluation of these nanoparticles against prostate cancer both in vitro and in vivo and the reported mode of action and the different types of anticancer experiments used; how the phytochemicals can also improve the targeting effects of these nanoparticles in some instances; and the potential toxicity of these nanoparticles.

Biogenic silver based nanostructures: Synthesis, mechanistic approach and biological applications

The alarming impact of antibiotic resistance sparked the quest for complementary treatments to overcome the confrontation over resistant pathogens. Metallic nanoparticles, especially silver nanoparticles (Ag NPs) have gained a much attention because of their remarkable biological characteristics. Moreover, their medicinal properties can be enhanced by preparing the composites with other materials. This article delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism, methods and favorable experimental parameters. Comprehensive biological features Ag NPs such as antibacterial, antiviral, antifungal have been examined, with a focus on their potential uses in biomedicine and diagnostics has also been discussed. Additionally, we have also explored the hitches and potential outcomes of biosynthesis of Ag NPs in biomedical filed.

Green synthesis, characterization, and antibacterial activity of Citrus lanatus based silver nanoparticles

Due to their enhanced and unique physicochemical characteristics, such as their minimal dimensions, large surface area compared to their mass and increased reactivity, nanomaterials hold promise in the field of antibacterial therapy. The aim of this study is to evaluate the method for Green Synthesis, Characterization of Citrus lanatus pulp, rind, and seed-based Silver Nanoparticles, and study its antibacterial activity against common oral microorganisms. Green synthesis of nanoparticles was formulated using the extract from the rind, seed, and pulp of Citrullus lanatus and silver nitrate extract. The extract was stirred in a magnetic stirrer for 24 hours, and centrifugation was done at 8000 rpm for 10 minutes. The synthesized nanoparticles were characterized and utilized for the antibacterial study. The characterization was done using UV-visible light spectroscopy, and antibacterial activity was assessed using the well diffusion method and measuring the zone of inhibition. The nanoparticles synthesized were characterized using UV-visible spectroscopy, and the spectroscopic analysis confirmed the formation of silver particles in this study. At 450 nm, a sharp peak was observed, which correlated to the SPR band of the particles. The results showed that the zone of inhibition assessed was comparable to the standard. From this study it can be concluded that silver nanoparticles (AgNPs) produced by green synthesis from Citrullus lanatus showed significant antibacterial potential against common oral microflora.

The Protecting Activity of RIPACUT®: A New Therapeutic Approach Preserving Epithelial Health Based on the Combination of Iceland Lichen Extract, Silver Salt, and Sodium Hyaluronate

Epithelial integrity and function must be maintained in a dynamic healthy equilibrium, keeping unaltered the oxidative and inflammatory conditions and the microbiome of the cutaneous layers. Beside the skin, other mucous membranes can be injured, such as the nasal and anal ones, because of the contact with the external environment. Here, we detected the effects of RIPACUT^®, a combination of Iceland lichen extract, silver salt and sodium hyaluronate that individually act in diverse biological ways. The findings we obtained on keratinocytes, nasal and intestinal epithelial cells reveal that this combination showed a marked antioxidant activity, further assessed by the DPPH assay. Additionally, by analyzing the release of the IL-1β, TNF-α and IL-6 cytokines, we proved the anti-inflammatory effect of RIPACUT^®. In both cases, the main preserving action was due to Iceland lichen. We also observed a notable antimicrobial activity mediated by the silver compound. These data suggest that RIPACUT^® could signify the basis for an attractive pharmacological approach to maintaining healthy epithelial conditions. Interestingly, this may be extended to the nasal and anal areas where it protects against oxidative, inflammatory and infectious insults. Thus, these outcomes encourage the creation of sprays or creams for which sodium hyaluronate can guarantee a surface film-forming effect.

Antimicrobial Activity of Green Synthesized Silver Nanoparticles Using Waste Leaves of Hyphaene thebaica (Doum Palm)

Silver nanoparticles (AgNPs) were biosynthesized for the first time from waste leaves extract of local doum palms in Tabuk, Saudi Arabia. The transmission electron microscope (TEM) revealed a spherical shape with a particle size from 18 to 33 nm. The d-spacing is about 2.6 Å, which confirms a face-centered cubic crystalline building. The biosynthesized AgNPs were evaluated as an antimicrobial agent against several pathogenic bacteria, including Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. The highest action was exerted against S. aureus ATCC 29213 (MIC = 1.5 µg/mL). Interestingly, AgNPs also showed anticandidal activity against the pathogenic yeasts Candida albicans ATCC 14053 (MIC = 24 µg/mL) and Candida tropicalis ATCC 13803 (MIC = 96 µg/mL). Scanning electron microscope (SEM) revealed deep morphological changes in Candida spp. due to the treatment of the AgNPs. Scarce pseudohyphae, perforation, exterior roughness, irregularly shaped cells, and production of protective exopolysaccharide (EPS) were the main features. In conclusion, the process of biosynthesis of AgNPs from the aqueous leaf extract of Hyphaene thebaica is environmentally compatible and induces the biosynthesis of tiny AgNPs that could be a promising candidate in biomedical applications, including antimicrobials against some pathogenic bacteria and yeasts.

Biological Response Evaluation of Human Fetal Osteoblast Cells and Bacterial Cells on Fractal Silver Dendrites for Bone Tissue Engineering

Prosthetic joint replacement is the most widely used surgical approach to repair large bone defects, although it is often associated with prosthetic joint infection (PJI), caused by biofilm formation. To solve the PJI problem, various approaches have been proposed, including the coating of implantable devices with nanomaterials that exhibit antibacterial activity. Among these, silver nanoparticles (AgNPs) are the most used for biomedical applications, even though their use has been limited by their cytotoxicity. Therefore, several studies have been performed to evaluate the most appropriate AgNPs concentration, size, and shape to avoid cytotoxic effects. Great attention has been focused on Ag nanodendrites, due to their interesting chemical, optical, and biological properties. In this study, we evaluated the biological response of human fetal osteoblastic cells (hFOB) and P. aeruginosa and S. aureus bacteria on fractal silver dendrite substrates produced by silicon-based technology (Si_Ag). In vitro results indicated that hFOB cells cultured for 72 h on the Si_Ag surface display a good cytocompatibility. Investigations using both Gram-positive (S. aureus) and Gram-negative (P. aeruginosa) bacterial strains incubated on Si_Ag for 24 h show a significant decrease in pathogen viability, more evident for P. aeruginosa than for S. aureus. These findings taken together suggest that fractal silver dendrite could represent an eligible nanomaterial for the coating of implantable medical devices.

Using inorganic nanoparticles to fight fungal infections in the antimicrobial resistant era

Fungal infections pose a serious threat to human health and livelihoods. The number and variety of clinically approved antifungal drugs is very limited, and the emergence and rapid spread of resistance to these drugs means the impact of fungal infections will increase in the future unless alternatives are found. Despite the significance and major challenges associated with fungal infections, this topic receives significantly less attention than bacterial infections. A major challenge in the development of fungi-specific drugs is that both fungi and mammalian cells are eukaryotic and have significant overlap in their cellular machinery. This lack of fungi-specific drug targets makes human cells vulnerable to toxic side effects from many antifungal agents. Furthermore, antifungal drug resistance necessitates higher doses of the drugs, leading to significant human toxicity. There is an urgent need for new antifungal agents, specifically those that can limit the emergence of new resistant species. Non-drug nanomaterials have primarily been explored as antibacterial agents in recent years; however, they are also a promising source of new antifungal candidates. Thus, this article reviews current research on the use of inorganic nanoparticles as antifungal agents. We also highlight challenges facing antifungal nanoparticles and discuss possible future research opportunities in this field. STATEMENT OF SIGNIFICANCE: Fungal infections pose a growing threat to human health and livelihood. The rapid spread of resistance to current antifungal drugs has led to an urgent need to develop alternative antifungals. Nanoparticles have many properties that could make them useful antimycotic agents. To the authors' knowledge, there is no published review so far that has comprehensively summarized the current development status of antifungal inorganic nanomaterials, so we decided to fill this gap. In this review, we discussed the state-of-the-art research on antifungal inorganic nanoparticles including metal, metal oxide, transition-metal dichalcogenides, and inorganic non-metallic particle systems. Future directions for the design of inorganic nanoparticles with higher antifungal efficacy and lower toxicity are described as a guide for further development in this important area.

Three-Dimensional Evaluation of the Cytotoxicity and Antibacterial Properties of Alpha Lipoic Acid-Capped Silver Nanoparticle Constructs for Oral Applications

There is a need to develop bifunctional scaffolds that provide antibacterial protection while encouraging host cell attachment/proliferation. This study evaluates HyStem®-C, and photo-cross-linked GelMA hydrogels for encapsulation and stabilisation of silver nanoparticles (AgNPs). We studied the behaviour of AgNPs and matrix interactions within both hydrogel systems. The cell viability of encapsulated human gingival fibroblasts (HGFs) was determined by Prestoblue® assay and live/dead staining. The release of AgNPs was monitored by inductively coupled plasma-mass spectroscopy. The antibacterial properties of the GelMA-AgNP constructs were determined using disc diffusion. Even distribution of AgNPs in GelMA induced a significant decrease in cell viability (p < 0.0001), whereas AgNP aggregates did not induce cytotoxicity in HyStem®-C. AgNPs doses ≥ 0.5 µg/mL in GelMA were significantly toxic to the HGFs (p < 0.0001). The release of AgNPs from GelMA after 48 h was 20% w/w for 0.1 µg/mL and 51% for 100 µg/mL of AgNPs. At ≥5 µg/mL, a significant intra-construct bactericidal effect was observed. The disc diffusion assay shows that GelMA-incorporated AgNPs were found to be effective against both Escherichia coli and Staphylococcus aureus at 50 and 100 µg/mL, respectively. Visible photo-cross-linked GelMA stably incorporated AgNPs to provide an antimicrobial regenerative construct for oral applications.

Silver Nanoparticles: Bactericidal and Mechanistic Approach against Drug Resistant Pathogens

This review highlights the different modes of synthesizing silver nanoparticles (AgNPs) from their elemental state to particle format and their mechanism of action against multidrug-resistant and biofilm-forming bacterial pathogens. Various studies have demonstrated that the AgNPs cause oxidative stress, protein dysfunction, membrane disruption, and DNA damage in bacteria, ultimately leading to bacterial death. AgNPs have also been found to alter the adhesion of bacterial cells to prevent biofilm formation. The benefits of using AgNPs in medicine are, to some extent, counter-weighted by their toxic effect on humans and the environment. In this review, we have compiled recent studies demonstrating the antibacterial activity of AgNPs, and we are discussing the known mechanisms of action of AgNPs against bacterial pathogens. Ongoing clinical trials involving AgNPs are briefly presented. A particular focus is placed on the mechanism of interaction of AgNPs with bacterial biofilms, which are a significant pathogenicity determinant. A brief overview of the use of AgNPs in other medical applications (e.g., diagnostics, promotion of wound healing) and the non-medical sectors is presented. Finally, current drawbacks and limitations of AgNPs use in medicine are discussed, and perspectives for the improved future use of functionalized AgNPs in medical applications are presented.

Green synthesis of silver nanoparticles using Eupatorium adenophorum leaf extract: characterizations, antioxidant, antibacterial and photocatalytic activities

The green synthesis of metallic nanoparticles has tremendous impacts in various fields as found in recent years due to their low cost, easy and environmentally friendly synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using an aqueous Eupatorium adenophorum (E. adenophorum) leaf extract as a bioreductant. Interestingly, Fourier transform infrared (FTIR) spectroscopy analysis established that the E. adenophorum extract not only served as a bioreductant but also acted as a capping agent to stabilize the nanoparticles by functionalizing the surfaces. Various characterization techniques were adopted, such as X-ray powder diffraction (XRD), FTIR, ultraviolet-visible absorption (UV-Vis) spectroscopy, dynamic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) to analyze the biosynthesized AgNPs. Biosynthesized nanoparticles were also explored for antioxidant, antibacterial and photocatalytic activities. The AgNPs showed improved free radical scavenging activity (IC₅₀ 48.96 ± 0.84 µg/mL) and bacterial inhibitory effects against both gram-positive (Staphylococcus aureus; 64.5 µg/mL) and gram-negative (Escherichia coli; 82.5 µg/mL) bacteria. Photocatalytic investigation showed AgNPs were effective at degrading rhodamine dye (78.69% in 90 min) when exposed to sunlight. These findings collectively suggest that E. adenophorum AgNPs were successfully prepared without the involvement of any hazardous chemical and it may be an effective antibacterial, antioxidant and promising agent for the removal of hazardous dye from waste water produced by industrial dyeing processes.

Chitosan–silver nanocomposites as a promising tool for controlling the bed bug: Cimex lectularius (Heteroptera: Cimicidae)

This study evaluates the use of chitosan–silver nanocomposites (CSN) as an insecticide against the bed bug ( Cimex lectularius). Adult bed bugs were collected from infested residential areas and identified using light microscopy and scanning electron microscopy. CSN were prepared and photographed for characterization using transmission electron microscopy, dynamic light scattering, and zeta potential. The insecticidal effect of different concentrations of CSN (400–1000 ppm) was compared to that of 0.1% cypermethrin as a positive control and normal saline as a negative control. The bugs ( n = 25) were immersed for 20 min in the corresponding medium, dried with filter papers, and then incubated at 27–28°C and 70% RH with a 12:12 h light–dark photoperiod. The mortality rates were recorded at different time intervals (2, 4, 6, 12, and 24 h post-incubation (hPI)), and the entire experiment was repeated five times. Image analysis showed round- to spherical-shaped CSN ranging in size from 34 to 72 nm. The mortality rates were positively associated with increasing concentrations of CSN. The mortality rate first reached 100% for concentrations of 800 ppm at 24 hPI and 1000 ppm at 12 hPI. The calculated LC50 was found at a concentration of 1165 ppm at 2 hPI, and the LC99 was found at a concentration of 1914 ppm at 2 hPI. The positive control, cypermethrin, induced 100% mortality among the bugs at 2 hPI, while the negative control caused no mortality. These results clearly show the potential of CSN as an insecticide against C. lectularius. Future studies on best practices for implementing these particles in clinical settings are recommended.

Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility

Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

Synergistic Antibacterial Potential of Greenly Synthesized Silver Nanoparticles with Fosfomycin Against Some Nosocomial Bacterial Pathogens

Introduction

A considerable number of morbidities and fatalities occur worldwide as a result of the multidrug resistant microorganisms that cause a high prevalence of nosocomial bacterial infections. Hence, the current investigation was conducted to evaluate the antibacterial potency of green fabricated silver nanoparticles (AgNPs) against four different nosocomial pathogens.

Methods

The flower extract of Hibiscus sabdariffa mediated green fabrication of AgNPs and their physicochemical features were scrutinized using different techniques. Antimicrobial activity of the biogenic AgNPs and their synergistic patterns with fosfomycin antibiotic were evaluated using disk diffusion assay.

Results and Discussion

UV spectral analysis affirmed the successful formation of AgNPs through the detection of broad absorption band at 395 and 524 nm, indicating the surface plasmon resonance of the biofabricated AgNPs. In this setting, the biofabricated AgNPs demonstrated average particle size of 58.682 nm according to transmission electron microscope (TEM) micrographs. The detected hydrodynamic diameter was higher than that noticed by TEM analysis, recording 72.30 nm in diameter and this could be attributed to the action of capping agents, which was confirmed by Fourier Transform Infrared (FT-IR) analysis. Disk diffusion assay indicated the antibacterial potency of biogenic AgNPs (50 μg/disk) against Enterobacter cloacae, Methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli strains with relative inhibition zone diameters of 12.82 ± 0.36 mm, 14.54 ± 0.15 mm, 18.35 ± 0.24 mm and 21.69 ± 0.12 mm, respectively. In addition, E. coli was found to be the most susceptible strain to the biogenic AgNPs. However, the highest synergistic pattern of AgNPs-fosfomycin combination was detected against K. pneumonia strain recording relative synergistic percentage of 64.22%. In conclusion, the detected synergistic efficiency of AgNPs and the antibiotic fosfomycin highlight the potential for utilizing this combination in the biofabrication of effective antibacterial agents against nosocomial pathogens.

Silver Nanoparticles Modified by Carbosilane Dendrons and PEG as Delivery Vectors of Small Interfering RNA

The fact that cancer is one of the leading causes of death requires researchers to create new systems of effective treatment for malignant tumors. One promising area is genetic therapy that uses small interfering RNA (siRNA). These molecules are capable of blocking mutant proteins in cells, but require specific systems that will deliver RNA to target cells and successfully release them into the cytoplasm. Dendronized and PEGylated silver nanoparticles as potential vectors for proapoptotic siRNA (siMCL-1) were used here. Using the methods of one-dimensional gel electrophoresis, the zeta potential, dynamic light scattering, and circular dichroism, stable siRNA and AgNP complexes were obtained. Data gathered using multicolor flow cytometry showed that AgNPs are able to deliver (up to 90%) siRNAs efficiently to some types of tumor cells, depending on the degree of PEGylation. Analysis of cell death showed that complexes of some AgNP variations with siMCL-1 lead to ~70% cell death in the populations that uptake these complexes due to apoptosis.

Dual mode antibacterial surfaces based on Prussian blue and silver nanoparticles

Prussian Blue (PB) is an inexpensive, biocompatible, photothermally active material. In this paper, self-assembled monolayers of PB nanoparticles were grafted on a glass surface, protected with a thin layer of silica and decorated with spherical silver nanoparticles. This combination of a photothermally active nanomaterial, PB, and an intrinsically antibacterial one, silver, leads to a versatile coating that can be used for medical devices and implants. The intrinsic antibacterial action of nanosilver, always active over time, can be enhanced on demand by switching on the photothermal effect of PB using near infrared (NIR) radiation, which has a good penetration depth through tissues and low side effects. Glass surfaces functionalized by this layer-by-layer approach have been characterized for their morphology and composition, and their intrinsic and photothermal antibacterial effect was studied against Gram+ and Gram- planktonic bacteria.

Synthesis and characterization of plant extracted silver nanoparticles and advances in dental implant applications

Dental implantology has always emphasized silver nanoparticles (AgNPs) for various applications due to their biocompatibility, antibacterial activity, and increased surface volume ratio offered by these particles. It is utilized to a large extent in the dental implant industry as a surface modification, biocompatible constituent and composite material. AgNPs may be produced inexpensively, sustainably, and environmentally responsibly by utilizing technologies that extract the plant material. The phytochemical components that are contained in plants make them a better, non-toxic, and more cost-effective alternative to both physical and chemical approaches. Because the size and shape of AgNP depend on their synthesis method and technique, and because the efficacy and toxicity of AgNP depend on both size and shape, synthesis methods and techniques have recently become the focus of a significant amount of research attention. In this review, we discussed Plant Extracted Ag-NP's whose sizes range up to 100nm. This review also focuses on recent research advancements in the Plant Extracted synthesis of AgNPs, as well as their characterization methodologies, current obstacles, future possibilities, and applications in dental implantology.

Antibacterial Coatings for Titanium Implants: Recent Trends and Future Perspectives

Titanium and its alloys are widely used as implant materials for biomedical devices owing to their high mechanical strength, biocompatibility, and corrosion resistance. However, there is a significant rise in implant-associated infections (IAIs) leading to revision surgeries, which are more complicated than the original replacement surgery. To reduce the risk of infections, numerous antibacterial agents, e.g., bioactive compounds, metal ions, nanoparticles, antimicrobial peptides, polymers, etc., have been incorporated on the surface of the titanium implant. Various coating methods and surface modification techniques, e.g., micro-arc oxidation (MAO), layer-by-layer (LbL) assembly, plasma electrolytic oxidation (PEO), anodization, magnetron sputtering, and spin coating, are exploited in the race to create a biocompatible, antibacterial titanium implant surface that can simultaneously promote tissue integration around the implant. The nature and surface morphology of implant coatings play an important role in bacterial inhibition and drug delivery. Surface modification of titanium implants with nanostructured materials, such as titanium nanotubes, enhances bone regeneration. Antimicrobial peptides loaded with antibiotics help to achieve sustained drug release and reduce the risk of antibiotic resistance. Additive manufacturing of patient-specific porous titanium implants will have a clear future direction in the development of antimicrobial titanium implants. In this review, a brief overview of the different types of coatings that are used to prevent implant-associated infections and the applications of 3D printing in the development of antibacterial titanium implants is presented.

Biomedical Applications of Plant Extract-Synthesized Silver Nanoparticles

Silver nanoparticles (AgNPs) have attracted a lot of interest directed towards biomedical applications due in part to their outstanding anti-microbial activities. However, there have been many health-impacting concerns about their traditional synthesis methods, i.e., the chemical and physical methods. Chemical methods are commonly used and contribute to the overall toxicity of the AgNPs, while the main disadvantages of physical synthesis include high production costs and high energy consumption. The biological methods provide an economical and biocompatible option as they use microorganisms and natural products in the synthesis of AgNPs with exceptional biological properties. Plant extract-based synthesis has received a lot of attention and has been shown to resolve the limitations associated with chemical and physical methods. AgNPs synthesized using plant extracts provide a safe, cost-effective, and environment-friendly approach that produces biocompatible AgNPs with enhanced properties for use in a wide range of applications. The review focused on the use of plant-synthesized AgNPs in various biomedical applications as anti-microbial, anti-cancer, anti-inflammatory, and drug-delivery agents. The versatility and potential use of green AgNPs in the bio-medicinal sector provides an innovative alternative that can overcome the limitations of traditional systems. Thus proving green nanotechnology to be the future for medicine with continuous progress towards a healthier and safer environment by forming nanomaterials that are low- or non-toxic using a sustainable approach.

Novel archetype in cancer therapeutics: exploring prospective of phytonanocarriers

This paper reports various types of cancer, their incidence, and prevalence all over the globe. Along with the discovery of novel natural drugs for cancer treatment, these present a promising option which are eco-friendly, safe, and provide better acceptability in comparison to synthetic agents that carries multiple side effects. This paper provides an idea about various nanocarriers and phytochemicals, along with how their solubility and bioavailability can be enhanced in nanocarrier system. This report combines the data from various literature available on public domain including PubMed on research articles, reviews, and along with report from various national and international sites. Specialized metabolites (polyphenols, alkaloids, and steroids etc) from medicinal plants are promising alternatives to existing drugs. Studies have suggested that the treatment of cancer using plant products could be an alternative and a safe option. Studies have shown with the several cell lines as well as animal models, that phytomolecules are important in preventing/treating cancer. Phytochemicals often outperform chemical treatments by modulating a diverse array of cellular signaling pathways, promoting cell cycle arrest, apoptosis activation, and metastatic suppression, among others. However, limited water solubility, bioavailability, and cell penetration limit their potential clinical manifestations. The development of plant extract loaded nanostructures, rendering improved specificity and efficacy at lower concentrations could prove effective. Nanocarriers, such as liposomes, nanostructured lipids, polymers, and metal nanoparticles, have been tested for the delivery of plant products with enhanced effects. Recent advances have achieved improvement in the the stability, solubility, bioavailability, circulation time, and target specificity by nanostructure-mediated delivery of phytochemicals. Nanoparticles have been considered and attempted as a novel, targeted, and safe option. Newer approaches such as phyto-nanocarriers with carbohydrates, lignin, and polymers have been considered even more selective and effective modes of drug delivery in biomedical or diagnostic applications.

Application of Plant-Derived Nanoparticles (PDNP) in Food-Producing Animals as a Bio-Control Agent against Antimicrobial-Resistant Pathogens

Antibiotics are regularly used in animal husbandry to treat diseases. This practice is beneficial to animals' health and helps ensure food security. However, the misuse of antibiotics, especially in food-producing animals, has resulted in the advent of antimicrobial resistance (AMR) and its dissemination among foodborne pathogens. The occurrence of AMR in bacteria pathogens that cause infections in animals and those associated with food spoilage is now considered a global health concern affecting humans, animals and the environment. The search for alternative antimicrobial agents has kindled the interest of many researchers. Among the alternatives, using plant-derived nanoparticles (PDNPs) for treating microbial dysfunctions in food-producing animals has gained significant attention. In traditional medicine, plant extracts are considered as safe, efficient and natural antibacterial agents for various animal diseases. Given the complexity of the AMR and concerns about issues at the interface of human health, animal health and the environment, it is important to emphasize the role of a One Health approach in addressing this problem. This review examines the potential of PDNPs as bio-control agents in food-producing animals, intending to provide consumers with microbiologically safe food while ensuring food safety and security, better health for animals and humans and a safe environment.

Silver Nanoparticle-Based Therapy: Can It Be Useful to Combat Multi-Drug Resistant Bacteria?

The present review focuses on the potential use of silver nanoparticles in the therapy of diseases caused by antibiotic-resistant bacteria. Such bacteria are known as “superbugs”, and the most concerning species are Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus (methicillin and vancomycin-resistant), and some Enterobacteriaceae. According to the World Health Organization (WHO), there is an urgent need for new treatments against these “superbugs”. One of the possible approaches in the treatment of these species is the use of antibacterial nanoparticles. After a short overview of nanoparticle usage, mechanisms of action, and methods of synthesis of nanoparticles, emphasis has been placed on the use of silver nanoparticles (AgNPs) to combat the most relevant emerging resistant bacteria. The toxicological aspects of the AgNPs, both in vitro using cell cultures and in vivo have been reviewed. It was found that toxic activity of AgNPs is dependent on dose, size, shape, and electrical charge. The mechanism of action of AgNPs involves interactions at various levels such as plasma membrane, DNA replication, inactivation of protein/enzymes necessary, and formation of reactive oxygen species (ROS) leading to cell death. Researchers do not always agree in their conclusions on the topic and more work is needed in this field before AgNPs can be effectively applied in clinical therapy to combat multi-drug resistant bacteria.

Metal-Based Nanoparticles: Antibacterial Mechanisms and Biomedical Application

The growing increase in antibiotic-resistant bacteria has led to the search for new antibacterial agents capable of overcoming the resistance problem. In recent years, nanoparticles (NPs) have been increasingly used to target bacteria as an alternative to antibiotics. The most promising nanomaterials for biomedical applications are metal and metal oxide NPs, due to their intrinsic antibacterial activity. Although NPs show interesting antibacterial properties, the mechanisms underlying their action are still poorly understood, limiting their use in clinical applications. In this review, an overview of the mechanisms underlying the antibacterial activity of metal and metal oxide NPs will be provided, relating their efficacy to: (i) bacterial strain; (ii) higher microbial organizations (biofilm); (iii) and physico-chemical properties of NPs. In addition, bacterial resistance strategies will be also discussed to better evaluate the feasibility of the different treatments adopted in the clinical safety fields. Finally, a wide analysis on recent biomedical applications of metal and metal oxide NPs with antibacterial activity will be provided.

Synthetic Conditions, Physical Properties, and Antibacterial Activities of Silver Nanoparticles with Exopolysaccharides of a Medicinal Fungus

Natural polysaccharides are attractive and promising biomacromolecules for the green synthesis of silver nanoparticles (Ag NPs) with a broad spectrum of useful functions. This study aims to evaluate the synthetic conditions and physical properties of Ag NPs using three fractions of exopolysaccharide (EPS), namely EPS-1, EPS-2, and EPS-3, produced by a medicinal fungus known as Cs-HK1, with variations in their chemical composition and molecular weight. Each of the EPS fractions had a unique set of optimal synthetic conditions (reaction time course, temperature, and reagent concentration), resulting in a specific range of Ag NP size distributions. The Ag NPs synthesized with the EPS-1 fraction had the smallest particle size (~160 nm) and the most significant antibacterial activities against Escherichia coli (Gram-) and Staphylococcus aureus (Gram+), with a minimal inhibitory concentration (MIC) of 0.2 mg/mL on E. coli and 0.075 mg/mL on S. aureus. The results proved the success of the scheme of this green synthesis scheme with all three EPS fractions and the potential antibacterial application of EPS-coated Ag NPs.

Green Nano-Biotechnology: A New Sustainable Paradigm to Control Dengue Infection

Dengue is a growing mosquito-borne viral disease prevalent in 128 countries, while 3.9 billion people are at high risk of acquiring the infection. With no specific treatment available, the only way to mitigate the risk of dengue infection is through controlling of vector, i.e., Aedes aegypti. Nanotechnology-based prevention strategies like biopesticides with nanoformulation are now getting popular for preventing dengue fever. Metal nanoparticles (NPs) synthesized by an eco-friendly process, through extracts of medicinal plants have indicated potential anti-dengue applications. Green synthesis of metal NPs is simple, cost-effective, and devoid of hazardous wastes. The recent progress in the phyto-synthesized multifunctional metal NPs for anti-dengue applications has encouraged us to review the available literature and mechanistic aspects of the dengue control using green-synthesized NPs. Furthermore, the molecular bases of the viral inhibition through NPs and the nontarget impacts or hazards with reference to the environmental integrity are discussed in depth. Till date, major focus has been on green synthesis of silver and gold NPs, which need further extension to other innovative composite nanomaterials. Further detailed mechanistic studies are required to critically evaluate the mechanistic insights during the synthesis of the biogenic NPs. Likewise, detailed analysis of the toxicological aspects of NPs and their long-term impact in the environment should be critically assessed.

Biological Synthesis of Silver Nanoparticles and Prospects in Plant Disease Management

Exploration of nanoparticles (NPs) for various biological and environmental applications has become one of the most important attributes of nanotechnology. Due to remarkable physicochemical properties, silver nanoparticles (AgNPs) are the most explored and used NPs in wide-ranging applications. Also, they have proven to be of high commercial use since they possess great chemical stability, conductivity, catalytic activity, and antimicrobial potential. Though several methods including chemical and physical methods have been devised, biological approaches using organisms such as bacteria, fungi, and plants have emerged as economical, safe, and effective alternatives for the biosynthesis of AgNPs. Recent studies highlight the potential of AgNPs in modern agricultural practices to control the growth and spread of infectious pathogenic microorganisms since the introduction of AgNPs effectively reduces plant diseases caused by a spectrum of bacteria and fungi. In this review, we highlight the biosynthesis of AgNPs and discuss their applications in plant disease management with recent examples. It is proposed that AgNPs are prospective NPs for the successful inhibition of pathogen growth and plant disease management. This review gives a better understanding of new biological approaches for AgNP synthesis and modes of their optimized applications that could contribute to sustainable agriculture.

New Insights for Exploring the Risks of Bioaccumulation, Molecular Mechanisms, and Cellular Toxicities of AgNPs in Aquatic Ecosystem

Silver nanoparticles (AgNPs) are commonly used in numerous consumer products, including textiles, cosmetics, and health care items. The widespread usage of AgNPs results in their unavoidable discharge into the ecosystem, which pollutes the aquatic, groundwater, sediments, and marine environments. These nanoparticles (NPs) activate the production of free radicals reactive species in aquatic organisms that interrupt the functions of DNA, cause mitochondrial dysfunction, and increase lipid peroxidation, which terminates the development and reproduction both in vivo and in vitro. The life present in the aquatic ecosystem is becoming threatened due to the release and exploitation of AgNPs. Managing the aquatic ecosystem from the AgNP effects in the near future is highly recommended. In this review, we discussed the background of AgNPs, their discharge, and uptake by aquatic organisms, the mechanism of toxicity, different pathways of cytotoxicity, and bioaccumulation, particularly in aquatic organisms. We have also discussed the antimicrobial activities of AgNPs along with acute and chronic toxicity in aquatic groups of organisms.

ZnO/Ag Nanocomposites with Enhanced Antimicrobial Activity

In this study, ZnO/Ag nanocomposites were synthesized using a facile chemical route involving metallic precursors of zinc acetate dehydrate and silver acetate, and dissolving the two metallic precursors in EtOH. The final concentration of the solution was 0.4 M. The different nanocomposites were synthesized using different atomic percentages of silver to compare the amount of silver nanoparticles with the bactericidal power of the nanocomposites. They were prepared at concentrations of 0, 1, 3, 5, 7, and 10 at%. The as-prepared nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) to study their structural and morphological properties. SEM showed that there is a clear effect of Ag on the size of the ZnO particles, since when silver percentages of 1 at% are included, the grain size obtained is much smaller than that of the ZnO synthesis. The effect is maintained for 3, 5, 7, and 10 at% silver. Transmission electron microscopy (TEM) compositional mapping confirms the presence of spherical nanoparticles in the synthesized samples. The size of the nanoparticles ranges from about 10 to about 30 nm. In addition, UV-Vis and Raman spectroscopy were performed to obtain structural details. The different samples show an increase in the absorption in the visible range due to the incorporation of the silver NPs. Measurement of the antimicrobial activity was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) It is shown that zinc oxide has bactericidal power for these two groups of bacteria and also that when it is used together with silver NP, this effect improves, eliminating more than 90% of inoculated bacteria.

Nanocomposites of Graphene Oxide-Silver Nanoparticles for Enhanced Antibacterial Activity: Mechanism of Action and Medical Textiles Coating

The resistance of microorganisms to antibiotics is a crucial problem for which the application of nanomaterials is among a growing number of solutions. The aim of the study was to create a nanocomposite (composed of graphene oxide and silver nanoparticles) with a precise mode of antibacterial action: what enables textiles to be coated in order to exhibit antibacterial properties. A characterization of nanomaterials (silver nanoparticles and graphene oxide) by size distribution, zeta potential measurements, TEM visualization and FT-IR was performed. The biological studies of the nanocomposite and its components included the toxicity effect toward two pathogenic bacteria species, namely Pseudomonas aeruginosa and Staphylococcus aureus, interaction of nanomaterials with the outer layer of microorganisms, and the generation of reactive oxygen species and lipid peroxidation. Afterwards, antibacterial studies of the nanocomposite’s coated textiles (cotton, interlining fabric, polypropylene and silk) as well as studies of the general toxicity towards a chicken embryo chorioallantoic membrane model were conducted. The toxicity of the nanocomposite used was higher than its components applied separately (zones of growth inhibition for P. aeruginosa for the final selected concentrations were as follows: silver nanoparticles 21 ± 0.7 mm, graphene oxide 14 ± 1.9 mm and nanocomposite 23 ± 1.6 mm; and for S. aureus were: silver nanoparticles 27 ± 3.8 mm, graphene oxide 14 ± 2.1 mm, and nanocomposite 28 ± 0.4 mm. The viability of P. aeruginosa and S. aureus after treatment with selected GO-Ag decreased to 27% and 31%, respectively, compared to AgNPs, when the viability of both species was 31% and 34%, accordingly). The coated textiles showed encouraging antibacterial features without general toxicity towards the chicken embryo chorioallantoic membrane model. We demonstrated that graphene oxide might constitute a functional platform for silver nanoparticles, improving the antibacterial properties of bare silver. Due to the application of the nanocomposite, the textiles showed promising antibacterial features with a low general toxicity, thereby creating a wide possibility for them to be used in practice.

Photochemical effect of silver nanoparticles on flesh fly larval biological system

With the progress of nanoscience and its applications, silver nanoparticles (AgNPs) have become one of the most interesting nanoparticles owing to their use in different fields. However, the excessive use of AgNPs and its products may cause toxicity in both the environment and in human health. The main goal of this research is to study the toxic and photochemical effects of AgNPs against Sarcophaga argyrostoma larvae through ultrastructure, morphological change, and DNA damage. Treating midgut epithelium with AgNPs led to many alterations in dark conditions, disintegrated epithelium, swollen cells, and shrunken nucleus. Organelles appeared in a loose manner and mitochondria were without cristae, endoplasmic reticulum had dark spots, and peritrophic membrane was loose in appearance. Fatty tissues were vacuolized and muscle fibers lacked normal striations and had many gaps and lysosomal bodies. In the light conditions, the epithelium appeared with detached cells and many vacuoles, organelles were ruptured with many gaps in between, and secretory vesicles were scattered. Peritrophic membrane disappeared. Muscles collapsed and vacuolized loosed fatty tissues were detected. On the other hand, control larvae epithelium appeared regularly distinct, with organelles intact and muscles had clear normal striations. Data showed that AgNPs caused ultrastructural and morphological changes of the external cuticle of the 4th instar larvae along with a significant effect on DNA damage that occurred after the larval treatment, reflecting the toxicity of AgNPs.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.