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

Solution processing for colloidal nanoparticle thin film: From fundamentals to applications

Colloidal nanoparticles (NPs) are widely used as building blocks to construct thin film devices owing to their numerous advantages and unique size-dependent properties. The performance of NP-based devices is highly dependent on the film fabrication method and structure. Therefore, understanding the various solution-based thin film fabrication methods is critical for maximizing the device performance by controlling the NP film structures. This review article surveys eleven representative solution processes (dip coating, blade coating, slot-die coating, Mayer rod coating, inkjet printing, roll-to-roll printing, brush coating, drop casting, spin coating, spray coating, and electrophoretic deposition) using colloidal NPs as building blocks. The merits/limitations and basic deposition mechanisms of these processes are discussed in this review for a broad audience to facilitate their customization to individual industrial or laboratory conditions. This review article also aims to provide insights into how solution processing affects the NP thin film device properties by introducing recent achievements and providing the readers with in-depth information that can aid future research.

Application of green waste polyphenols in natural antimicrobial materials for the environmental fields: A review

In recent years, green waste polyphenols (GWPs) have attracted global attention due to their abundant renewable resources and excellent antibacterial properties. We analyzed the research progress on the antimicrobial properties of natural polyphenol composites (including polyphenol-metal nanoparticles, polyphenol nanofiber membranes, polyphenol-polymer membranes, and polyphenol hydrogels) in environmental applications. The waste sources of polyphenols and the latest extraction technologies were systematically summarized, and a universal hydrodynamic cavitation-integrated membrane technology combined with polyphenol extraction and purification process was initially constructed. The inhibitory effects of GWPs on pathogenic bacteria and the antibacterial properties of polyphenol composites in the environmental field were systematically analyzed. These composites exhibited outstanding antimicrobial performance, effectively inhibiting E. coli and S. aureus by up to 100%, especially in water treatment and air filtration. In addition, the advantages, challenges, and prospects for the application of green waste polyphenol antibacterial materials (GWPAMs) in the environmental field are discussed. With high efficiency, low toxicity, antimicrobial resistance, and sustainable antimicrobial properties, GWPs exhibit significant application potential in the "resource recycling-pollution control-ecological restoration" synergistic system within the environmental field. Future work should focus on the green synthesis of polyphenol composites, conducting systematic and thorough investigations on their antibacterial mechanisms, and enhancing their antibacterial properties in agriculture, waste treatment, and soil remediation, to improve their environmental adaptability and sustainable application value.

Advanced antimicrobial surfaces in cellulose-based food packaging

This critical review provides a comprehensive framework for selecting engineered colloidal and nanostructured systems for cellulose-based food packaging. Meta-analysis was used as a methodological approach to categorize them according to antimicrobial agents, coating methods, and synergistic effects against a broad spectrum of microorganisms. The most frequent substrate is flexible packaging paper (35-70 g/m2, uncalendered), often intended for food wrapping. Among antimicrobial agents, chitosan-based coatings are a common choice-often combined with essential oils-being particularly effective against Gram-positive bacteria (e.g., Staphylococcus aureus, Listeria monocytogenes, Bacillus subtilis). This is attributed to electrostatic interactions between the polysaccharide's protonated -NH3+ groups and teichoic acids within bacterial cell walls. Inorganic metal nanoparticles, such as ZnO nanorods and Ag nanoparticles, are broadly effective by compromising the membranes of various foodborne pathogens-including Bacillus cereus and Pseudomonas aeruginosa. Terpenoid- or phenolic-rich essential oils-commonly delivered in emulsions or encapsulated in host-guest β-cyclodextrin complexes-inhibit the growth of yeasts and molds, besides some common bacteria when grafted onto bleached paper. Synergistic effects have been observed with complex coatings such as chitosan combined with CuONPs. Despite their promising performance, the widespread industrial adoption of cellulose-based active packaging in the food sector requires addressing not only antimicrobial activity, but also barrier properties and feasible methods to functionalize the paper surface (e.g., bar coating). These challenges, often overlooked, are critically assessed herein. All considered, further studies are required to address the challenges of cellulosic antimicrobial materials in a holistic manner to accelerate its large-scale implementation in the food sector.

Green synthesized AgNPs of the Anchusa arvensis aqueous extract resulting in impressive protein kinase, antioxidant, antibacterial, and antifungal activities

This study focused on analyzing the pharmacological activities of AgNPs synthesized from an aqueous plant extract of Anchusa arvensis. The effectiveness of AgNPs was evaluated for protein kinase inhibition, antioxidant, antibacterial, and antifungal activities. The AgNPs and plant were used to regulate the protein kinase activity using the liquid TSB and ISP4 medium protein kinase inhibition study demonstrated that nanoparticles exhibited a larger zone of inhibition (9.1 ± 0.8) compared to the plant extract (8.1 ± 0.6). The antioxidant activity was assessed using DPPH reagent, and the results indicated that AgNPs displayed potent free radical scavenging properties. In terms of antibacterial activity, AgNPs showed higher efficacy against Enterobacter aerogens (20.1 ± 0.9), Bordetella bronchiseptaca (19.1 ± 0.9), and Salmonella typhimurium (17.2 ± 0.8) at 4 mg/mL. The antifungal activity of AgNPs was prominent against Aspergillus fumagatus (14.1 ± 0.9), Mucor species (19.2 ± 0.8), and Fusarium solani (11.2 ± 0.8) at 20 mg/mL. These findings suggest that AgNPs possess multiple beneficial properties, including bactericidal/fungicidal effects, protein kinase inhibition, and potential free radical scavenging abilities. Therefore, AgNPs have potential applications in various fields, such as biomedicine and industry, due to their ability to counteract the harmful effects of free radicals.

Advancements in silver-based nanocatalysts for organic transformations and other applications: a comprehensive review (2019-2024)

Over time, nanocomposites have revolutionized materials science, offering numerous applications in fields such as catalysis, environmental purification and treatment, biomedicine and various industries. Among these, silver-based nanocomposites are particularly notable for their remarkable stability, reusability, biocompatibility, and multifunctional medicinal properties. Hence, we present a comprehensive summary of recent developments (2019-2024) in silver-based nanomaterials, focusing on their applications across multiple domains, including catalytic organic transformations, biomedical uses, environmental remediation, and industrial sectors such as food packaging, agriculture and textiles. By highlighting recent advancements and emerging trends, we aim to provide a thorough understanding of the role of silver-based nanocomposites in contemporary science and technology, emphasizing their potential to drive innovation across diverse disciplines.

Inorganic Nanomaterials Meet the Immune System: An Intricate Balance

The immune system provides defense against foreign agents that are considered harmful for the organism. Inorganic nanomaterials can be recognized by the immune system as antigens, inducing an immune reaction dependent on the patient's immunological anamnesis and from several factors including size, shape, and the chemical nature of the nanoparticles. Furthermore, nanomaterials-driven immunomodulation might be exploited for therapeutic purposes, opening new horizons in oncology and beyond. In this scenario, we present a critical review of the state of the art regarding the preclinical evaluation of the effects of the most promising metals for biomedical applications (gold, silver, and copper) on the immune system. Because exploiting the interactions between the immune system and inorganic nanomaterials may result in a game changer for the management of (non)communicable diseases, within this review we encounter the need to summarize and organize the plethora of sometimes inconsistent information, analyzing the challenges and providing the expected perspectives. The field is still in its infancy, and our work emphasizes that a deep understanding on the influence of the features of metal nanomaterials on the immune system in both cultured cells and animal models is pivotal for the safe translation of nanotherapeutics to the clinical practice.

Functional analysis and modification of anti-lipopolysaccharide factor (ALF) from the freshwater crab Sinopotamon henanense and preparation of a novel ShALF6-2 K-AgNPs complex

Overuse of antibiotics has led to the emergence of drug-resistant bacteria and environmental problems. Antimicrobial peptides (AMPs) and silver nanoparticles (AgNPs) can potentially replace antibiotics. Therefore, it is possible to create composite nanostructures with synergistic bactericidal properties by combining AgNPs and AMPs. In this study, a novel anti-lipopolysaccharide factor 6, named ShALF6, was identified in the freshwater crab Sinopotamon henanense. Full-length ShALF6 is 654 bp long and contains a typical lipopolysaccharide-binding domain spanning from Cys51 to Lys72. ShALF6 is highly expressed in hemocytes and responds to infection by the gram-negative bacterium Aeromonas hydrophila. ShALF6 inhibited the growth of gram-negative bacteria by binding to them and disrupting their cell membranes. To alter the charge of ShALF6, the negatively charged glutamic acid (E) in the sequence was replaced with a positively charged lysine (K) and the modified protein was named ShALF6-2 K. The bacteriostatic activity of ShALF6-2 K was significantly enhanced by an increase in the protein's cations. ShALF6-2 K showed high binding efficiency after 36 h of co-incubation with AgNPs and modifying the surface potential of the AgNPs. ShALF6-2 K-AgNPs exhibited synergistic inhibition with enhanced effectiveness against gram-negative bacteria. Finally, the cytotoxicity of ShALF6-2 K-AgNPs was investigated. The combination of ShALF6-2 K and AgNPs significantly reduced the toxic effects of AgNPs on the cells. This study provides theoretical and experimental bases for the development of novel bioactive AMP-coated composite AgNPs.

Green biosynthetic silver nanoparticles from Ageratum conyzoides as multifunctional hemostatic agents: Combining hemostasis, antibacterial, and anti-inflammatory properties for effective wound healing

Widespread interest in new hemostatic agents arises from the challenge of simultaneously satisfying the requirements of hemostatic, antibacterial, and anti-inflammatory properties while also considering the associated economic costs. An ideal hemostasis material should facilitate rapid hemostasis, intervene against infection, promote wound healing, and be cost-effective and easy to prepare. Herein, we demonstrate that medicinal plant-derived silver nanoparticles (AgNPs) exhibit the potential to constitute a promising multifunctional hemostatic reagent library. Biogenic synthesis of AgNPs utilizing Ageratum conyzoides extracts, referred to as AC-AgNPs, successfully combines the hemostatic and anti-inflammatory properties of Ageratum conyzoides with the inherent antibacterial activity exhibited by AgNPs. In-vitro coagulation experiments indicate that AC-AgNPs have a strong hemostatic effect, which is related to their size, concentration, and negative charge, and they exhibit low cytotoxicity and hemolysis. Subsequent experiments including scanning electron microscopy, flow cytometry, western blotting, and network pharmacology analysis have revealed that AC-AgNPs can cause platelet activation and aggregation, stimulated kallikrein-kinin system, shorten activated partial thromboplastin and prothrombin time, and increase fibrinogen content. These findings indicate that AC-AgNPs act on multiple signaling pathways, including endogenous and exogenous coagulation pathways, complement system, platelet activation, and aggregation. Furthermore, the hemostatic efficacy of AC-AgNPs is demonstrated in mouse models of tail amputation and liver injury, where AC-AgNPs significantly reduce the amount of blood loss and the bleeding time. Our work shows that AC-AgNPs possess strong hemostatic, anti-inflammatory, and antibacterial capabilities, ultimately facilitating wound healing. The biogenic synthesis of AgNPs from medicinal plants could be a multifunctional hemostatic candidate for practical application.

New insights into chitosan-Ag nanocomposites synthesis: Physicochemical aspects of formation, structure-bioactivity relationship and mechanism of antioxidant activity

Herein, a novel approach to the controlled formation of chitosan-Ag nanocomposites (NCs) with different structures and tunable chemical/biological properties was proposed. The chitosan-Ag NCs were obtained using hydrothermal synthesis and varying the concentrations of components. The hypothesis of chitosan-Ag NC synthesis using polysaccharide coils as a "microreactor" system was confirmed. A comparative analysis of the physicochemical characteristics of the NCs with single-core-shell and multi-core-shell structures was carried out, and the "structure-property" relationship was revealed. The obtained NCs exhibited excellent antiradical properties, comparable to the activity of phenolic acids: the IC50 values were 0.051, 0.022, and 0.019 mg/mL for CS7, CS5, and caffeic acid, respectively. A mechanism for the antiradical activity of chitosan-Ag NCs was discussed. The redox activity of the NCs was found to be 11.4 and 2.3 mg ABTS per 1 mg of Ag in CS5 and CS7, respectively. The proposed environmentally friendly one-pot, one-step synthesis of silver nanoparticles inside chitosan "microreactors" represents an innovative approach to designing hybrid materials with nanoscale control of desired structure and properties. These findings pave the way for further optimization of biopolymer‑silver nanostructures for various biomedical and industrial applications, including the design of a new type of hybrid catalysts such as nanozymes.

Novel green synthesis of silver nanoparticles using carotenoid extracted from Kocuria sp.: determination of antioxidant, antimicrobial, and anti-human breast cancer activities

In recent decades, nanotechnology has emerged as a promising field with diverse medical applications. Silver nanoparticles (Ag NPs) exhibit several biological activities. The aim of the current study was to investigate antioxidant, antimicrobial, and anti-breast cancer properties of green-synthesized Ag NPs. To achieve this, Ag NPs were synthesized using Kocuria sp., and their successful formation and physicochemical properties were evaluated using UV-vis, FTIR, XRD, DLS, zeta potential analysis, SEM, and TEM. The antioxidant capacity of Ag NPs was evaluated using a DPPH scavenging assay. The antimicrobial effects of the Ag NPs were tested on two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) using a 96-well plate. HUVEC, MCF7, and MDA-MB-231 cells were treated with varying concentrations of Ag NPs, and cell viability, migration, and apoptosis rates were assessed using MTT, scratch, and flow cytometry assays, respectively. Additionally, qPCR was performed to analyze the expression levels of some genes involved in apoptosis, such as caspases 3, 8, and 9. Characterization techniques confirmed the successful synthesis of pure crystalline structures and spherical Ag NPs. Antioxidant and antimicrobial assays demonstrated the significant antioxidant capacity of the Ag NPs and their antibacterial properties against all tested bacteria. Moreover, in vitro studies indicated that Ag NPs effectively inhibited cell proliferation, suppressed migration, and induced apoptosis, likely owing to the upregulation of caspase 3, 8, and 9 and BCL2 downregulation genes. Our findings suggest that green-synthesized Ag NPs using carotenoids extracted from Kocuria sp. might serve as promising antibacterial and anti-breast cancer agents; however, more in vitro and in vivo investigations are required to elucidate the therapeutic potential of Ag NPs.

Bioactive silver nanoparticles derived from Carica papaya floral extract and its dual-functioning biomedical application

Replacing synthetic phytochemicals with natural plant extracts for metal nanoparticle synthesis enable cost-effective, large-scale production with reduced environmental and health risks while enhancing biomedical efficacy. This study presents the green synthesis of silver nanoparticles (AgNPs) using a flavonol-enriched extract from male papaya flowers (KQE), an underutilized agricultural waste. Using 20% (v/v) KQE, highly stable, spherical KQ-AgNPs (12.3 ± 3.0 nm) were synthesized via in-situ generation of free radicals, such as ortho-quinones, which reduced Ag+ ions. KQ-AgNPs exhibit superior antibacterial activity against both gram-positive and gram-negative bacteria compared to chemically synthesized AgNPs (AgNPs-Chem) and KQE alone. In vitro anticancer assays reveal enhanced cytotoxicity against breast carcinoma cells (MCF-7) with an IC50 of 21.25 ± 1.14 µg/mL, significantly lower than AgNPs-Chem (33.05 ± 3.13 µg/mL), while maintaining high biocompatibility with normal cells (HEK-293) with a greater IC50 of 169.96 ± 2.3 µg/mL. This study highlights the dual therapeutic potential of KQ-AgNPs, emphasizing their enhanced antibacterial and anticancer efficacy while exemplifying an innovative waste-to-wealth approach.

Green synthesis of silver nanoparticles from the endophytic fungus Panax notoginseng and their antioxidant and antimicrobial activities and effects on cherry tomato preservation

This study investigated endophytic fungi isolated from the medicinal plant Panax notoginseng. Among these, the endophytic fungus SQ3, identified as Chaetomium globosum, was capable of reducing silver ions to form metallic silver nanoparticles. The green-synthesized silver nanoparticles (AgNPs) presented a distinct surface plasmon resonance peak at 424 nm, with particle sizes between 2.92 and 31.34 nm, indicating strong antioxidant activity. In vitro assessments demonstrated that AgNPs exhibited significant antifungal activity against Phytophthora infestans, Botrytis cinerea, and Helminthosporium maydis. AgNPs produced inhibition zones measuring 17.5 mm, 15.2 mm, and 13.4 mm against Staphylococcus aureus, Escherichia coli, and Bacillus subtilis, respectively. When applied to cherry tomatoes, AgNP treatment effectively inhibited the growth of Botrytis cinerea, minimized weight loss, preserved fruit firmness and soluble solids content, slowed the reduction in titratable acidity, and prolonged storage life. Additionally, AgNPs suppressed the increase in malondialdehyde content and maintained increased superoxide dismutase activity. These findings highlight the potential of green biosynthetic silver nanoparticles as biological control agents, providing promising resources for developing innovative treatments against postharvest fungal infections in crops.

Unlocking the Synergistic Potential and Efficacy of Biosurfactant-Silver Nanoparticle for Enhanced Antimicrobial Activities

Microorganisms can produce various amphiphilic compounds known as biosurfactants, with diverse applications in distinct industries. This study was focused on the biosurfactant production by Limosilactobacillus fermentum HBUAS62516 for the synthesis of silver nanoparticles. The biosurfactant obtained was characterized as glycolipid using FTIR which showed prominent peaks at 2932.3, 1116.3, and 1084.4 cm-1, indicating major functional groups which was further confirmed using techniques, such as EDS, NMR, and HPLC. Biosurfactant was utilized as the reducing agent for the biosynthesis of silver nanoparticles which was confirmed using UV-Vis spectral measurements that showed maximum absorbance at 421 nm and FTIR revealed peaks at 109 and 665 cm-1, indicating silver nanoparticle formation. EDS confirmed the presence of silver nanoparticles with a mass percentage of 100.00 ± 4.56%. Dynamic light scattering (DLS) and zeta potential were 87.93 nm and - 21 mV, respectively, indicating stability. The nanoparticles showed significant antibiofilm and antioxidant activity (90.1%). The synergistic antibacterial effect of the biosurfactant and nanoparticles was studied against Staphylococcus aureus and Pseudomonas putida, as well as their antifungal activity against Aspergillus niger, with a MIC value of 12.5 μg/mL. Nanoparticles synthesized using biosurfactants obtained from probiotic bacteria can act as alternative therapeutics to treat infections caused by the biofilm-forming bacteria.

Preparation of nanosilver/polymer composites and evaluation of their antimicrobial and antitumor effect

In this study, a copolymer (PVA-g-PEG) of polyethylene glycol (PEG) and polyvinyl alcohol (PVA) was synthesized by grafting PEG chains onto PVA backbone. PVA-g-PEG was used as the carrier to prepare the silver nanoparticles/polymer composite (AgNPs/PVA-g-PEG) using a "one-pot" biological method in the presence of grape seeds extract as a reducing and stabilizing agent. In order to highlight the effect of the copolymer, the homo-polymers PVA and PEG were applied as the carriers to prepare the corresponding composites - AgNPs/PVA, and AgNPs/PEG, respectively using the same method. The prepared AgNPs/polymer products were characterized by UV absorption spectroscopy (UV-vis), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the silver ions were successfully reduced by the grade seeds extract and the produced AgNPs are coated on the surface of AgNPs/PVA-g-PEG and AgNPs/PVA, but not for AgNPs/PEG. The prepared AgNPs are uniform and monodisperse, the particle size is small with mean diameter about 25.7 ± 2.3 nm and 54.2 ± 3.4 nm for AgNPs/PVA-g-PEG and AgNPs/PVA, respectively. The AgNPs/polymer composites exhibited superior antimicrobial effects against microorganisms (Escherichia coli and Staphylococcus aureus). AgNPs/PVA-g-PEG demonstrated a better performance than AgNPs/PVA. AgNPs/PVA-g-PEG had a minimum inhibitory concentration (MIC) of 1.3 μg mL-1 and a minimum inhibitory concentration (MBC) of 2.4 μg mL-1 against the microorganisms. For anti-tumor effect, AgNPs/PVA-g-PEG also demonstrated a high cytotoxicity to the colorectal cancerous cells HCT116 and SW620. The IC50 values of AgNPs/PVA-g-PEG for HCT116 and SW620 cell lines were 25.4 and 37.6 μg mL-1, respectively, suggesting a good anticancer activity. All above results indicate that AgNPs/PVA-g-PEG composites have a significant potential for the control of microorganisms and inhibition of cancer cells.

A Durable Ag@MOF-545/QCM-Cotton Fabric with "Intelligent Bacteria-Capturing and Dual Antibacterial" Properties

Cotton textiles with persistent antibacterial qualities are crucial in halting the spread of bacteria and other infections. However, fugitive bacteria and drug-resistant pathogens have rendered tremendous challenges in the development of cotton fabrics with long-lasting antibacterial efficacy. The work aimed to innovatively propose a functional cotton fabric integrating intelligent bacteria-capturing and dual antibacterial properties for efficacious personal health management. The functional cotton fabric was created by modifying the surface of cotton fabric with the quaternized carboxymethyl chitosan (Q-CF) and then covalently grafting the silver@Zr-based porphyrin metal-organic skeleton (Ag@MOF-545) prepared via the "bottle-around-the-boat" method on the surface of Q-CF (AM/Q-CF). In this process, the functional cotton fabric could capture bacteria via positive charges on the surface of the quaternized carboxymethyl chitosan. Due to the synergistic effect of broad-spectrum antibacterial silver nanoparticles (AgNPs) and the visible light-driven antibacterial Zr-based porphyrin metal-organic skeleton (MOF-545), the metabolism of bacteria and drug-resistant strains was well inhibited, which endowed the AM/Q-CF with lasting dual antibacterial properties. After repeated laundering cycles, abrasion cycles, simulated sweat soaking, and long-term storage, the antibacterial rates of AM/Q-CF were over 85%. Altogether, the results provided a potential antibiotic-free alternative for the preparation of durable antibacterial cotton fabrics.

Silver functionalized chitosan composite hydrogel with sustained silver release and enhanced antibacterial properties promotes healing of infected wounds

Bacterial infections during wound healing often cause inflammation, which delays the healing process. Therefore, innovative wound dressings are urgently needed to inhibit bacterial infections and promote healing. This study proposes an Ag-functionalized chitosan hydrogel dressing, formed via a Schiff-base reaction between alkynyl Ag substituted chitosan (Ag-CS) and octafunctionalized polyhedral oligomeric silsesquioxane with benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO), to address the issue of bacterial infection in wounds. The hydrogel demonstrated excellent injectability and self-healing properties. AgNPs and alkynyl Ag, produced by the reducing effect of chitosan and the reversible reaction of alkynyl Ag, delay the release of Ag+. Furthermore, the hydrogel exhibits a broad-spectrum antibacterial effect and effectively inhibits bacterial biofilm formation. The release of Ag+ lasts for 7 days, ensuring sustainable antibacterial properties. In a mouse infected wound model, the composite hydrogel significantly accelerated wound healing. By the eighth day, the wound healing rate reached 99 %, whereas the control group achieved only 91 %. Histological and immunofluorescence staining results indicated that hydrogel-treated wounds had faster re-epithelialization, collagen deposition, and angiogenesis, with reduced inflammation. In conclusion, the Ag-functionalized chitosan hydrogel, with sustained Ag release and enhanced antibacterial properties, shows great potential as a wound dressing for promoting the healing of infected wounds.

Extracellular Biosynthesis, Characterization and Antimicrobial Activity of Silver Nanoparticles Synthesized by Filamentous Fungi

The green synthesis of metal nanoparticles has received substantial attention due to their applications in various domains. The aim of the study was to obtain silver nanoparticles (AgNPs) by green synthesis with filamentous fungi, such as Cladosporium cladosporoides, Penicillium chrysogenum, and Purpureocillium lilacinum. Fungal species were grown on nutrient media and aqueous mycelium extracts were used to reduce Ag+ to Ag (0). The silver nanoparticles were analyzed by various techniques, such as UV-Visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Zeta potential. The formation of silver nanoparticles was confirmed by UV-Vis spectroscopy and the color change of the mixture containing metal precursor and aqueous mycelium extract. FTIR displayed different functional groups as capping and reducing agents for the biosynthesis of AgNPs. SEM and TEM provided information on the particles' morphology. DLS diagrams indicated mean particle diameters in the 124-168 nm region. All biosynthesized AgNPs had negative zeta values, which is a sign of good stability. Silver nanoparticles were evaluated for antimicrobial activity, and the most active were those synthesized with metabolites from Cladosporium, leading to 93.75% inhibition of Staphylococcus aureus, 67.20% of Escherichia coli, and 69.56% of Candida albicans. With the highest microbial inhibition percentage and a very good Poly Dispersion Index (Pd I), Cladosporium cladosporoides was selected as an environmentally friendly source of silver nanoparticles that could be used as a potential antimicrobial agent.

AgNPs with CNTs to construct multifunctional flexible sensor with dual conductive network structure

Flexible sensors play an important role in the field of smart devices. However, most flexible sensors suffer from poor sensing signal stability and monofunction. In this study, a multifunctional film (named PM) with dual conductive network structure was fabricated by nanocellulose crystal dispersed with silver nanoparticles and carbon nanotube. The PM film exhibited excellent conductivity (24.6 S/m) along with antimicrobial effects against Staphylococcus aureus and Escherichia coli. Furthermore, the PM sensor showed excellent electrothermal performance, reaching 133.1 °C within 50 s at 12 V, and an excellent temperature coefficient of resistance (TCR = -0.65 % °C-1) over a temperature range of 36-124 °C. More importantly, the PM sensor demonstrated a high strain sensitivity (GF = 1.66) and durability (320 cycles), capable of detecting minute human body movements at a strain as low as 1 %. Additionally, the PM sensor maintained a stable sensing performance even after 30 d of exposure to air. Therefore, the multifunctional integration of the PM sensor shows great potential for application in the field of flexible electronics.

Green Synthesis of Silver Nanoparticles with Roasted Green Tea: Applications in Alginate-Gelatin Hydrogels for Bone Regeneration

The incorporation of silver nanoparticles (AgNPs) into alginate-gelatin (Alg-Gel) hydrogels can enhance the properties of these materials for bone regeneration applications, due to the antimicrobial properties of AgNPs and non-cytotoxic concentrations, osteoinductive properties, and regulation of stem cell proliferation and differentiation. Here, the hydrogel formulation included 2% (w/v) sodium alginate, 4 µg/mL AgNPs, and 2.5% (w/v) gelatin. AgNPs were synthesized using a 2% (w/v) aqueous extract of roasted green tea with silver nitrate. The aqueous extract of roasted green tea for AgNP synthesis was characterized using HPLC and UHPLC-ESI-QTOF-MS/MS, and antioxidant capacity was measured in Trolox equivalents (TE) from 4 to 20 nmol/well concentrations. Stem cells from human exfoliated deciduous tooth cells were used for differentiation assays including positive (SHEDs/hydrogel with AgNPs) and negative controls (hydrogel without AgNPs). FTIR was used for hydrogel chemical characterization. Statistical analysis (p < 0.05, ANOVA) confirmed significant findings. Roasted green tea extract contained caffeine (most abundant), (-)-Gallocatechin, gallic acid, and various catechins. XRD analysis revealed FCC structure, TEM showed quasispheroidal AgNPs (19.85 ± 3 nm), and UV-Vis indicated a plasmon surface of 418 nm. This integration of nanotechnology and biomaterials shows promise for addressing bone tissue loss in clinical and surgical settings.

Recombinant Keratin-Chitosan Cryogel Decorated with Gallic Acid-Reduced Silver Nanoparticles for Wound Healing

Background

Wound healing is a complex physiological process that can be roughly divided into four stages: hemostasis, inflammation, proliferation, and remodeling. Conventional wound dressings often fail to meet the diverse needs of these healing stages due to their limited functionality. Cryogels, however, possess several attractive properties, such as large, interconnected pores, good mechanical strength, and ease of modification, making them suitable for developing advanced dressings with multiple functions. In this study, we developed a multifunctional cryogel dressing, with biocompatible polysaccharides as the main component, designed to provide a breathable, moist, and antibacterial microenvironment for chronic infected wounds, thereby promoting wound healing.

Methods

Recombinant keratin 31 (RK31) was combined with chitosan (CS) to produce a CS/RK31 cryogel, referred to as CK. Gallic acid-reduced silver nanoparticles (GA/Ag NPs) were incorporated as the active antibacterial component to create the CS/K31@GA/Ag cryogel, known as CKGA. The cryogel was characterized using scanning electron microscopy (SEM) and a universal testing machine, and its biocompatibility was assessed in vitro. The dynamic hemostatic performance of the cryogel was evaluated with a rat tail amputation bleeding model. Additionally, the antibacterial effects of the cryogel against Staphylococcus aureus and Escherichia coli were tested using agar diffusion assays and turbidimetry. The antioxidant capacity of the CKGA cryogel was also measured in vitro. Finally, the cryogel's ability to promote wound healing was tested in an SD rat model of infected wounds.

Results

Characterization results showed that the CKGA cryogel features an interpenetrating porous network structure and exhibits excellent mechanical properties, with a swelling rate of up to 1800%. Both in vitro and in vivo experiments confirmed that the cryogel has good biocompatibility, effectively absorbs exudates, and rapidly stops bleeding. The addition of GA/Ag NPs provided significant antibacterial effects, achieving an inhibition rate of over 99.9% against both S. aureus and E. coli. Furthermore, CKGA cryogels demonstrated a strong scavenging capacity for ROS in a dose-dependent manner. Studies using the SD rat infected wound model showed that the cryogel effectively inhibited bacterial proliferation on wound surfaces, reduced local tissue inflammation, and promoted the healing of infected wounds.

Conclusion

The multifunctional cryogel, with its rapid hemostatic, antibacterial, and antioxidant properties, as well as its ability to promote cell proliferation, could be widely used as a wound dressing for the healing of bacterial infections.

Synthesis of metal nanoparticles on graphene oxide and antibacterial properties

Pathogen-induced infections and the rise of antibiotic-resistant bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), pose significant global health challenges, emphasizing the need for new antimicrobial strategies. In this study, we synthesized graphene oxide (GO)-based composites functionalized with silver nanoparticles (AgNPs) and copper nanoparticles (CuNPs) as potential alternatives to traditional antibiotics. The objective is to assess the antibacterial properties of these composites and explore their efficacy against E. coli and S. aureus, two common bacterial pathogens. The composites are prepared using eco-friendly and conventional methods to ensure effective nanoparticle attachment to the GO surface. Structural and morphological characteristics are confirmed through SEM, AFM, EDS, XRD, UV-vis, FTIR, and Raman spectroscopy. The antibacterial efficacy of the composites is tested through disk diffusion assays, colony-forming unit (CFU) counts, and turbidimetry analysis, with an emphasis on understanding the effects of different nanoparticle concentrations. The results demonstrated a dose-dependent antibacterial effect, with GO/AgNP-1 showing superior antibacterial activity over GO/AgNP-2, particularly at lower concentrations (32.0 μg/mL and 62.5 μg/mL). The GO/CuNP composite also exhibited significant antibacterial properties, with optimal performance at 62.5 μg/mL for both bacterial strains. Turbidimetry analysis confirmed the inhibition of bacterial growth, especially at moderate concentrations, although slight nanoparticle aggregation at higher doses reduced efficacy. Lastly, both GO/AgNP and GO/CuNP composites demonstrated significant antibacterial potential. The results emphasize the need to fine-tune nanoparticle concentration and refine synthesis techniques to improve their efficacy, positioning these composites as strong contenders for antimicrobial use.

Green synthesis of polyethylene glycol coated, ciprofloxacin loaded CuO nanoparticles and its antibacterial activity against Staphylococcus aureus

Antibacterial resistance requires an advanced strategy to increase the efficacy of current therapeutics in addition to the synthesis of new generations of antibiotics. In this study, copper oxide nanoparticles (CuO-NPs) were green synthesized using Moringa oleifera root extract. CuO-NPs fabricated into a form of aspartic acid-ciprofloxacin-polyethylene glycol coated copper oxide-nanotherapeutics (CIP-PEG-CuO) to improve the antibacterial activity of NPs and the efficacy of the drug with controlled cytotoxicity. These NPs were charachterized by Fourier transform infrared spectroscopy (FTIR), x-rays diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Antibacterial screening and bacterial chemotaxis investigations demonstrated that CIP-PEG-CuO NPs show enhanced antibacterial potential against Gram-positive and Gram-negative clinically isolated pathogenic bacterial strains as compared to CuO-NPs. In ex-vivo cytotoxicity CIP-PEG-CuO-nano-formulates revealed 88% viability of Baby Hamster Kidney 21 cell lines and 90% RBCs remained intact with nano-formulations during hemolysis assay. An in-vivo studies on animal models show that Staphylococcus aureus were eradicated by this newly developed formulate from the infected skin and showed wound-healing properties. By using specially designed nanoparticles that are engineered to precisely transport antimicrobial agents, these efficient nano-drug delivery systems can target localized infections, ensure targeted delivery, enhance efficacy through increased drug penetration through physical barriers, and reduce systemic side effects for more effective treatment.

Musa paradisiaca L. peel extract-bioinspired anisotropic nano-silver with the multipurpose of hydrogenation eco-catalyst and antimicrobial resistance

In an effort to pursue a green synthesis approach, the biosynthesis of nano-silver (nAg) using plant extracts has garnered significant attention, particularly for its antimicrobial resistance and medical applications, which have been the focus of numerous studies. However, there remains a gap in surface catalytic studies, especially regarding the hydrogenation of 4-nitrophenol. While some studies have addressed catalytic kinetics, thermodynamic aspects have been largely overlooked, leaving the catalytic mechanisms of biosynthesized nAg unclear. In this context, the present work offers a straightforward, eco-friendly, and efficient protocol to obtain nano-silver inspired by Musa paradisiaca L. peel extract. This nAg serves multiple purposes, including antimicrobial resistance and as an eco-catalyst for hydrogenation. Predominantly consisting of zero-valent silver with anisotropic polyhedral shapes, mainly decahedra with an edge length of 50 nm, this nAg demonstrated effective antimicrobial action against both S. aureus and E. coli bacteria. More importantly, both kinetic and thermodynamic studies on the hydrogenation of 4-nitrophenol to 4-aminophenol catalyzed by this bio-inspired nAg revealed that the rate-limiting step is not diffusion-limited. Instead, the adsorbed hydrogen and 4-nitrophenolate react together via electron transfer on the surface of the nAg. The activation energy of 26.24 kJ mol-1 indicates a highly efficient eco-catalyst for such hydrogenation processes.

Advancements in Green Nanoparticle Technology: Focusing on the Treatment of Clinical Phytopathogens

Opportunistic pathogenic microbial infections pose a significant danger to human health, which forces people to use riskier, more expensive, and less effective drugs compared to traditional treatments. These may be attributed to several factors, such as overusing antibiotics in medicine and lack of sanitization in hospital settings. In this context, researchers are looking for new options to combat this worrying condition and find a solution. Nanoparticles are currently being utilized in the pharmaceutical sector; however, there is a persistent worry regarding their potential danger to human health due to the usage of toxic chemicals, which makes the utilization of nanoparticles highly hazardous to eukaryotic cells. Multiple nanoparticle-based techniques are now being developed, offering essential understanding regarding the synthesis of components that play a crucial role in producing anti-microbial nanotherapeutic pharmaceuticals. In this regard, green nanoparticles are considered less hazardous than other forms, providing potential options for avoiding the extensive harm to the human microbiome that is prevalent with existing procedures. This review article aims to comprehensively assess the current state of knowledge on green nanoparticles related to antibiotic activity as well as their potential to assist antibiotics in treating opportunistic clinical phytopathogenic illnesses.

Research progress of nanoparticles in diagnosis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most common malignant liver tumors. Despite progress in anticancer drugs and surgical approaches, early detection of HCC remains challenging, often leading to late-stage diagnosis where rapid disease progression precludes surgical intervention, leaving chemotherapy as the only option. However, the systemic toxicity, low bioavailability, and significant adverse effects of chemotherapy drugs often lead to resistance, rendering treatments ineffective for many patients. This article outlines how nanoparticles, following functional modification, offer high sensitivity, reduced drug toxicity, and extended duration of action, enabling precise targeting of drugs to HCC tissues. Combined with other therapeutic modalities and imaging techniques, this significantly enhances the diagnosis, treatment, and long-term prognosis of HCC. The advent of nanomedicine provides new methodologies and strategies for the precise diagnosis and integrated treatment of HCC.

Charge Effect of Mercaptobenzimidazole-Modified Ultrasmall Gold-Nanoparticles against Drug-Resistant Bacteria

The threat of bacterial infections, especially drug-resistant strains, to human health necessitates the development of high-efficient, broad-spectrum and nonantibiotic nanodisinfectant. However, the effect of interfacial charge on the antibacterial properties of nanodisinfectant remains a mystery, which greatly limits the development of highly antibacterial active nanodisinfectant. Herein, we developed three types of ultrasmall (d < 3 nm) gold-nanoparticles (AuNPs) modified with 5-carboxylic(C)/methoxy(M)amino(A)/-2-mercaptobenzimidazole (C/M/A MB) to investigate their interfacial charge on antibacterial performance. Our results showed that both the electropositive AMB-AuNPs and electronegative CMB-AuNPs exhibited no antibacterial activity against both Gram-positive (G+) and Gram-negative (G-) bacteria. However, the electroneutral MMB-AuNPs exhibited unique antibacterial performance against both G+ and G- bacteria, even against methicillin-resistant Staphylococcus aureus (MRSA). Mechanistic investigation revealed a multipathway synergistic bacteriostatic mechanism involving MMB-AuNPs inducing damage to bacterial cell membranes, disruption of membrane potential and downregulation of ATP levels, ultimately leading to bacterial demise. Furthermore, two additional electroneutral AuNPs modified with 5-methyl-2-mercaptobenzimidazole (mMB-AuNPs) and 5-ethoxy-2-mercaptobenzimidazole (EMB-AuNPs) also demonstrated commendable antibacterial efficacy against E. coli, S. aureus, and MRSA; however, their performance was comparatively inferior to that of MMB-AuNPs. This work provides valuable insights for the development of high-performance antibacterial nanomaterials.

Nanocomposites against Pseudomonas aeruginosa biofilms: Recent advances, challenges, and future prospects

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that causes life-threatening and persistent infections in immunocompromised patients. It is the culprit behind a variety of hospital-acquired infections owing to its multiple tolerance mechanisms against antibiotics and disinfectants. Biofilms are sessile microbial aggregates that are formed as a result of the cooperation and competition between microbial cells encased in a self-produced matrix comprised of extracellular polymeric constituents that trigger surface adhesion and microbial aggregation. Bacteria in biofilms exhibit unique features that are quite different from planktonic bacteria, such as high resistance to antibacterial agents and host immunity. Biofilms of P. aeruginosa are difficult to eradicate due to intrinsic, acquired, and adaptive resistance mechanisms. Consequently, innovative approaches to combat biofilms are the focus of the current research. Nanocomposites, composed of two or more different types of nanoparticles, have diverse therapeutic applications owing to their unique physicochemical properties. They are emerging multifunctional nanoformulations that combine the desired features of the different elements to obtain the highest functionality. This review assesses the recent advances of nanocomposites, including metal-, metal oxide-, polymer-, carbon-, hydrogel/cryogel-, and metal organic framework-based nanocomposites for the eradication of P. aeruginosa biofilms. The characteristics and virulence mechanisms of P. aeruginosa biofilms, as well as their devastating impact and economic burden are discussed. Future research addressing the potential use of nanocomposites as innovative anti-biofilm agents is emphasized. Utilization of nanocomposites safely and effectively should be further strengthened to confirm the safety aspects of their application.

Environmentally friendly silver nanoparticles synthesized from Verbascum nudatum var. extract and evaluation of its versatile biological properties and dye degradation activity

In the present study, green synthesis of silver nanoparticles (VNE-AgNPs) via Verbascum nudatum extract was carried out for the first time. The synthesized AgNPs were characterized by different spectral methods such as UV-vis, FTIR, XRD, TEM, and EDAX. According to TEM analyses, the average size range of AgNPs was 17-21 nm, and the dominant peaks in the 111°, 200°, 221°, and 311° planes in the XRD pattern indicated the Ag-NPs FCC crystal structure. FTIR data showed that VNE-AgNPs interacted with many reducing, capping, and stabilizing phytochemicals during green synthesis. VNE-AgNPs had higher antibacterial activity against S. aureus and E. coli bacterial strains with a maximum inhibition zone of 21 and 18 mm, respectively, than penicillin 5 IU, used as a positive control in the study. The cytotoxic effect of VNE-AgNPs appeared at a concentration of 50 µg/mL in L929 cells and 5 µg/mL in cancer (A549) cells. When the impact of VNE-AgNPs and C-AgNPs on inflammation was compared, it was found that VNE-AgNPs increased TNF-α levels (333.45 ± 67.20 ng/mg-protein) statistically (p < 0.05) more than TNF-α levels (256.92 ± 27.88 ng/mg-protein) in cells treated with C-AgNPs. VNE-Ag-NPs were found to have a degradation efficiency of 65% against methylene blue (MB) dye within 3 h.

Antimicrobial and Cytotoxic Effect of Positively Charged Nanosilver-Coated Silk Sutures

Sutures are a crucial component of surgical procedures, serving to close and stabilize wound margins to promote healing. However, microbial contamination of sutures can increase the risk of surgical site infections (SSI) due to colonization by pathogens. This study aimed to tackle SSI by synthesizing positively charged silver nanoparticles (P-AgNPs) and using them to produce antimicrobial sutures. The P-AgNPs were reduced and stabilized using polyethylenimine (PEI), a cationic branched polymer. The physiochemical characteristics of P-AgNPs were confirmed from the surface plasmon resonance (SPR) peak at 419 nm, spherical morphology with a particle size range of 8-10 nm, PEI functional groups on NPs, a hydrodynamic diameter of 12.3 ± 2.4 nm, and a zeta potential of 31.3 ± 6 mV. Subsequently, the surfaces of silk sutures were impregnated with P-AgNPs at different time intervals (24, 48, and 96 h) using an ex situ method. Scanning electron microscopy (SEM) and tensile strength studies were conducted to determine the coating and durability of the NP-coated sutures. The NPs were quantified on sutures using inductively coupled plasma optical emission spectrophotometry (ICP-OES), which was in the range of 1-5 μg. Primarily, antimicrobial activity was studied using three microorganisms (Candida albicans, Streptococcus mutans, and Staphylococcus aureus) for both P-AgNPs and suture-coated P-AgNPs using the agar diffusion method. The results showed that only the NPs and NP-coated sutures exhibited enhanced antimicrobial effects against bacteria and fungi. Finally, the cytotoxicity of the sutures was investigated using stem cells from the apical papilla (SCAPs) for 24 h, which exhibited more than 75% cell viability. Overall, the results indicate that NP-coated sutures can potentially be used as antimicrobial sutures to diminish or inhibit SSI in postoperative or general surgery patients.

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.