Nanocomposites: silver nanoparticles and bacteriocins obtained from lactic acid bacteria against multidrug-resistant Escherichia coli and Staphylococcus aureus.

Drug-resistant bacteria such as Escherichia coli and Staphylococcus aureus represent a global health problem that requires priority attention. Due to the current situation, there is an urgent need to develop new, more effective and safe antimicrobial agents. Biotechnological approaches can provide a possible alternative control through the production of new generation antimicrobial agents, such as silver nanoparticles (AgNPs) and bacteriocins. AgNPs stand out for their antimicrobial potential by employing several mechanisms of action that can act simultaneously on the target cell such as the production of reactive oxygen species and cell wall rupture. On the other hand, bacteriocins are natural peptides synthesized ribosomally that have antimicrobial activity and are produced, among others, by lactic acid bacteria (LAB), whose main mechanism of action is to produce pores at the level of the cell membrane of bacterial cells. However, these agents have disadvantages. Nanoparticles also have limitations such as the tendency to form aggregates, which decreases their antibacterial activity and possible cytotoxic effects, and bacteriocins have a narrow spectrum of action, require high doses to be effective, and can be degraded by proteases. Given these limitations, nanoconjugates of these two agents have been developed that can act synergistically in the control of pathogenic bacteria resistant to antibiotics. This review focuses on knowing relevant aspects of the antibiotic resistance of E. coli and S. aureus, the characteristics of these new generation antibacterial agents, and their effect alone or forming nanoconjugates that are more effective against the multiresistant mentioned bacteria.

Eco-friendly synthesis of bioactive silver nanoparticles from black roasted gram (Cicer arietinum) for biomedical applications.

Green synthesis leverages biological resources such as plant extracts to produce cost-effectively and environmentally friendly NPs. In our study, silver nanoparticles (AgNPs) are biosynthesized using blank roasted grams (Cicer arietinum) as reducing agents. CA-AgNPs were characterized by a characteristic surface plasmon resonance (SPR) peak at 224 nm in the UV-Vis spectrum. FTIR analysis revealed functional groups with O-H stretching at 3410 cm-1, C-H stretching at 2922 cm-1, and C=O stretching at 1635 cm-1. XRD patterns exhibited sharp peaks at 33.2°, 38.4°, 55.7°, and 66.6°, confirming high crystallinity. Morphological analysis through FESEM indicated spherical CA-AgNPs averaging 500 nm in size, with EDS revealing Ag at 97.51% by weight. Antimicrobial assays showed zones of inhibition of 14 mm against Candida albicans, 18 mm against Escherichia coli., and 12 mm against Propionibacterium acnes. The total phenolic content of CA-AgNPs was 26.17 ± 13.54 mg GAE/g, significantly higher than the 11.85 ± 9.57 mg GAE/g in CA extract. The ABTS assay confirmed the antioxidant potential with a lower IC50 value of 1.73 ± 0.41 µg/mL, indicating enhanced radical scavenging activity. Anti-melanogenesis was validated through tyrosinase, showing inhibition rates of 97.97% at the highest concentrations. The anti-inflammatory was evaluated by western blot, which showed decreased expression of iNOS and COX-2. This study demonstrates the green synthesis of CA-AgNPs and its potential biomedical applications. The results of this study demonstrate that biosynthesized CA-AgNPs have key biological applications.

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

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

The adverse side effects of prenatal and postnatal rats' exposure to silver nanoparticles Induced toxicity.

Background: Silver nanotechnology is widely applied in industry and medicine, with an increased likelihood of environmental and food contamination. Aim: This study aimed to explore the adverse effects of orally administering silver nanoparticles (AgNPs) to pregnant or lactating female rats on adults and the development of their offspring. Methods: Forty female albino rats were used to assess the immediate impacts of AgNPs in two separate experiments. The experimental group received 1 ml of AgNPs, dissolved in deionized water, at doses of 0, 50, and 100 mg/kg of body weight from the 6th to the 15th day of gestation in pregnant albino rats. After a 20-day gestation period, euthanasia was performed on the female rats, followed by a gross examination post-dissection. Results: The feti were preserved in ethyl alcohol and Poin's solution for the identification of skeletal and visceral malformations. It was noticed that feti of dams that received AgNPs showed teratogenicities such as delayed ossification and deletion of bones or ribs. Notably, dams showed necrosis and satellitosis with evidence of behavioral alteration. While rats' pups showed only brain edema and no behavioral changes. Conclusion: AgNPs at a dose of 50 or 100 mg/kg induced teratogenic effect in terms of delayed ossification, abnormal limb formation, and brain edema in rat pups, however, induced necrosis and satellitosis in dam rats. Hence, greater emphasis should be placed on preventing exposure to Ag-NPs, especially among pregnant females.

Silver nanoparticles mediated apoptosis and cell cycle arrest in lung cancer A549.

The present study was aimed to synthesize the silver nanoparticles from Alangium salvifolium Wang. and evaluating its biomedical applications. The leaves of A. salvifolium collected and subjected for the standard procedure of Soxhlet extraction using distilled water as a solvent. With the help of an aqueous extract AgNPs were synthesized from silver nitrate using phyto-reduction method. Further, synthesized AgNPs were characterized using several analytical techniques such as UV, FTIR, SEM-EDX, XRD, particles size and zeta potential. Synthesized AgNPs were tested for antibacterial, antioxidant, anticancer for lung cancer cell line and flowcytometry-based pathway studies. The visual observation confirmed the formation of AgNPs from the aqueous extract by changing yellow to brown colour formation. Further, characterization techniques also confirmed the formation of AgNPs. Antibacterial activity results showed that the tested AgNPs were potent against bacterial pathogens with a higher zone of inhibition. Further, the antioxidant and anticancer activity of AgNPs revealed that the AgNPs have exhibited significant results with a good percentage of inhibition. Further, the flow cytometry studies confirmed that the AgNPs inducing apoptosis and cell cycle arrest in lung cancer. The phytochemicals of A. salvifolium plant have successfully synthesized AgNPs. In the case of performed biological activity, the synthesized silver nanoparticles exhibited potent activity. In future these AgNPs can be taken for molecular and in vivo studies to identify their efficacy using in vivo and molecular models.

Evaluation of cytotoxic potential of silver nanoparticles biosynthesized using essential oils of Jasminum sambac against breast cancer and bacterial cells.

Essential oils (EOs) which cover about 91% whole biomolecules formulated from Jasminum sambac leaves based on Gas chromatography-mass spectrometry were employed to identify structures. EOs were observed as good agents in the preparation of Silver nanoparticles (AgNPs) through the proposed mechanism that was attempted to interpret the pathway of the bio-preparation process. The characterization of EOs-AgNPs carried via ultraviolet-visible to reveal surface plasmon resonance at 420 nm, Fourier transform infrared to observe functional groups EOs compared to EOs-AgNPs. X-ray diffraction (XRD) revealed a broad chart owing to the small size of AgNPs in average size less than 10 nm calculated relying on image J software, spherical AgNPs with a small dispersive size observed by transmission electron microscopy. Quasi near spherical surface morphology of EOs-AgNPs had detected by field emission scanning electron microscope. EOs-AgNPs were assessed for their antibacterial potential against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria as suppressing bacterial agents. EOs-AgNPs had their anti-breast cancer MCF-7 cell line ability investigated by DNA fragmentation; cycle flow cytometry (apoptosis) at half maximal inhibitory concentration (IC50) was determined at 260 µg/mL which has been stated by cytotoxicity (MTT) assay. EOs-AgNPs have antibacterial and anticancer therapeutic potential, and it is safe, inexpensive, and scalable in the nanoscale range.

Effect of silver nanoparticles and REP-PCR typing of Staphylococcus aureus isolated from various sources.

This is the primary study at Matrouh Governorate to unveil antibiotic resistance, biofilm formation, silver nanoparticles (Ag-NPs) effect using electron microscopy, and REP-PCR analysis of Staphylococcus aureus strains isolated from COVID-19 patients, contaminated food, and Morel's diseased sheep and goats. A total of 15 S. aureus strains were isolated; five from each of the COVID-19 patients, Morel's diseased sheep and goats, and contaminated food. All strains were considered multidrug-resistant (MDR). All strains showed the presence of biofilm. Morphological changes in the cell surface of the bacterium were evidenced, and penetration with the rupture of some bacterial cells. Based on REP-PCR analysis, 4 clusters (C1-C4) with dissimilarity between clusters C1 and C2 8% and between C3 and C4 15%. Cluster I included 3 strains from contaminated food with a similarity of 97%, and Cluster II included 2 strains from contaminated food and 2 from COVID-19-infected patients with a similarity of 96% (confirming the zoonotic nature of this pathogen). Cluster III contained 4 strains isolated from Morel's diseased sheep & goats with a similarity ratio of 99% in comparison the 4th cluster contained 3 strains isolated from COVID-patients and one from Morel's diseased sheep & goats with a similarity ratio of 92%.

Silver nanoparticles modified with MoS2 and ß-cyclodextrin as SERS substrate for rapid determination of cysteamine hydrochloride in meat products.

An efficient Surface-enhanced Raman scattering (SERS) method for the detection of cysteamine hydrochloride (CSH) was developed by synthesizing a composite substrate comprising silver nanoparticles (AgNPs) functionalized with MoS2 and ß-cyclodextrin (ß-CD). The enhanced Raman signals of CSH by ß-CD/MoS2/AgNPs substrate were the contribution of electromagnetic enhancement (EM) as well as chemical enhancement (CM), and the enhancement factor (EF) can reach up to 3.11 × 106 (peak at 633 cm-1). Various instrumental techniques were used to characterize the substrate, such as X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and ultraviolet visible (UV-vis). The binding of ß-CD/MoS2/AgNPs and CSH was confirmed by UV-vis and Fourier transform infrared (FT-IR). The optimal experimental conditions were determined by single factor experiments as well as response surface model. The influences of different metal ions and analogous drugs on the detection of CSH were investigated. Under optimum conditions, a good linear correlation (R = 0.9997) was established for CSH in the range of 10.00-1000.00 nmol/L, and the limit of detection (LOD) was as low as 0.78 nmol/L (S/N = 3). The contents of CSH in meat samples were detected. The recovery was 96.6-103.1 %, and the relative standard deviation (RSD) of the measurement was 0.7-3.9 % (n = 7).

Bioinspired Flexible and Low-Voltage Organic Synaptic Transistors for UV Light-Driven Vision Systems.

Neuromorphic vision systems, particularly those stimulated by ultraviolet (UV) light, hold great potential applications in portable electronics, wearable technology, biological analysis, military surveillance, etc. Organic artificial synaptic devices hold immense potential in this field due to their ease of processing, flexibility, and biocompatibility. In this work, we have fabricated a flexible organic field-effect transistor (OFET) that utilizes chitosan-silver nanoparticles (AgNPs) composite material as the active dielectric material. During UV light illumination, both silver nanoparticles and the pentacene layer generate a large number of charge carriers. The photogenerated carriers lead to a more significant hole accumulation at the pentacene interface, resulting in a current rise. In the absence of light, the trapped electron in the silver nanoparticles persists for a longer duration, preventing the instant recombination with holes. This extended retention of electrons leads to the observed synaptic performance of the transistor. The use of aluminum oxide (Al2O3) as one of the dielectric layers enables the device to operate effectively at low voltage (<1 V). The device mimics various crucial synaptic properties of the brain, including short-term potentiation and long-term potentiation (STP and LTP), paired-pulse facilitation (PPF), spike-duration dependent plasticity (SDDP), spike-number dependent plasticity (SNDP), and spike-rate dependent plasticity (SRDP), etc. This work introduces an approach to develop flexible organic synaptic transistors that operate efficiently at low voltages, paving the way toward high-performance, UV light-driven neuromorphic vision systems.

Silver Nanoparticles Exposure Impairs Cardiac Development by Suppressing the Focal Adhesion Pathway in Zebrafish.

Introduction: The potential toxic effects of wastewater discharges containing silver nanoparticles (AgNPs) and their release into aquatic ecosystems on aquatic organisms are becoming a major concern for environmental and human health. However, the potential risks of AgNPs to aquatic organisms, especially for cardiac development by Focal adhesion pathway, are still poorly understood. Methods: The cardiac development of various concentrations of AgNPs in zebrafish were examined using stereoscopic microscope. The expression levels of cardiac development-related genes were analyzed by qRT-PCR and Whole-mount in situ hybridization (WISH). In addition, Illumina high-throughput global transcriptome analysis was performed to explore the potential signaling pathway involved in the treatment of zebrafish embryos by AgNPs after 72 h. Results: We systematically investigated the cardiac developing toxicity of AgNPs on the embryos of zebrafish. The results demonstrated that 2 or 4 mg/L AgNPs exposure induces cardiac developmental malformations, such as the appearance of pericardial edema phenotype. In addition, after 72 h of exposure, the mRNA levels of cardiac development-related genes, such as myh7, myh6, tpm1, nppa, tbx5, tbx20, myl7 and cmlc1, were significantly lower in AgNPs-treated zebrafish embryos than in control zebrafish embryos. Moreover, RNA sequencing, KEGG (Kyoto Encyclopedia of Genes) and Genomes and GSEA (gene set enrichment analysis) of the DEGs (differentially expressed genes) between the AgNPs-exposed and control groups indicated that the downregulated DEGs were mainly enriched in focal adhesion pathways. Further investigations demonstrated that the mRNA levels of focal adhesion pathway-related genes, such as igf1ra, shc3, grb2b, ptk2aa, akt1, itga4, parvaa, akt3b and vcla, were significantly decreased after AgNPs treatment in zebrafish. Conclusion: Thus, our findings illustrated that AgNPs could impair cardiac development by regulating the focal adhesion pathway in zebrafish.

NiO/AgNPs nanowell enhanced SERS sensor for efficient detection of micro/nanoplastics in beverages.

The ubiquity of plastic products has led to an increased exposure to micro and nano plastics across diverse environments, presenting a novel class of pollutants with substantial health implications. Emerging research indicates their capacity to infiltrate human organs, posing risks of tissue damage and carcinogenesis. Given the prevalent consumption of beverages as a primary vector for these plastics' entry into the human system, there is an imperative need for the advancement of precise detection methodologies in liquids. In this study, we introduce a substrate comprising a Nickel Oxide (NiO) nanosheet array decorated with Silver Nanoparticles (AgNPs) for the Surface-Enhanced Raman Spectroscopy (SERS) analysis of micro//nano plastics. This configuration, leveraging a unique nanowell architecture alongside silver plasmonic enhancement, demonstrates unparalleled sensitivity and repeatability in signal, facilitating the accurate quantification of these contaminants. Through the application of a portable Raman apparatus, this study successfully identifies prevalent micro/nano plastics including polystyrene (PS), polyethylene (PE), and polypropylene (PP), achieving detection sensitivities of 5 µg/mL, 25 µg/mL, and 25 µg/mL, respectively. Moreover, the substrate's efficacy extends to the detection of PS within commonly consumed beverages such as water, milk, and liquor with sensitivities of 25 µg/mL, 50 µg/mL, and 50 µg/mL, respectively. These findings highlight the substrate's potential as an expedient and effective sensor for the real-time monitoring of micro/nano plastic pollutants.

Molecular mechanisms of silver nanoparticle-induced neurotoxic injury and new perspectives for its neurotoxicity studies: A critical review.

Silver nanoparticles (AgNPs) garnered significant attention and applications in the field of nanotechnology due to their unique physicochemical properties. However, with the increasing exposure of AgNPs in the environment and biological systems, concerns about their potential neurotoxicity have also risen. Recent studies on the neurotoxic effects and mechanisms of AgNPs have often relied on traditional toxicological research methods and perspectives. This reliance has limited the extrapolation of these findings to the human brain environment and hindered a deep understanding of the neurotoxicity of AgNPs. This review first outlines the molecular mechanisms of AgNPs-induced neurotoxic injury from a traditional research perspective, identifying oxidative stress, inflammatory responses, and autophagy disorders as key areas of current research. Related molecular signaling pathways, including the nuclear transcription factor-κB (NF-κB) signaling pathway, the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, and the calcium signaling pathway, have been implicated in the neurotoxic injury process induced by AgNPs. Subsequently, we elucidated the unique advantages of the 3D brain organoids applied to the neurotoxicity study of AgNPs by drawing on relevant studies in the same field. We also emphasize that establishing a standardized 3D brain organoids construction platform is a crucial prerequisite for its widespread application. Furthermore, we suggest that future studies should explore the neurotoxicity mechanisms of AgNPs through the lenses of "adaptive homeostasis" and "structure-activity relationship analysis". In conclusion, the neurotoxicity of AgNPs should be comprehensively evaluated by integrating new research techniques and perspectives, ultimately allowing these nanoparticles to better serve human society.

Biofilm inhibition of Staphylococcus aureus by silver nanoparticles derived from Hellenia speciosa rhizome extract.

Staphylococcus aureus is the most common cause of serious health conditions because of the formation of biofilm, which lowers antibiotic efficacy and enhances infection transmission and tenacious behavior. This bacteria is a major threat to the worldwide healthcare system. Silver nanoparticles have strong antibacterial characteristics and emerged as a possible alternative. This work is most relevant since it investigates the parameters influencing the biogenic nanoparticle-assisted control of bacterial biofilms by Staphylococcus aureus. Nanoparticles were fabricated utilizing Hellenia speciosa rhizome extracts, which largely comprised physiologically active components such as spirost-5-en-3-yl acetate, thymol, stigmasterol, and diosgenin, enhanced with the creation of silver nanocomposites. GC-MS, XRD, DLS, SEM, EDX, FTIR and TEM were used to investigate the characteristics of nanoparticles. The microtiter plate experiment showed that nanoparticles destroyed biofilms by up to 92.41% at doses that ranged from 0 to 25 µg/ml. Fluorescence microscopy and SEM demonstrated the nanoparticles' capacity to prevent bacterial surface adhesion. EDX research revealed that the organic extract efficiently formed silver nanoparticles with considerable oxygen incorporation, which was attributed to phytochemicals that stabilize AgNPs and prevent accumulation. FTIR spectroscopy indicated the existence of hydroxyl, carbonyl, and carboxylate groups, which are essential for nanoparticle stability. TEM revealed that the AgNPs were spheroidal, with diameters ranging from 40 to 60 nm and an average of 46 nm. These results demonstrate the efficacy of H. speciosa extract in creating stable, well-defined AgNPs suited for a variety of applications. This work underlines the potential of green-synthesized AgNPs in biomedical applications, notably in the treatment of S. aureus biofilm-associated illnesses. The thorough characterization gives important information on the stability and efficiency of these biogenic nanoparticles.

AgNP Composite Silicone-Based Polymer Self-Healing Antifouling Coatings.

Biofouling poses a significant challenge to the marine industry, and silicone anti-biofouling coatings have garnered extensive attention owing to their environmental friendliness and low surface energy. However, their widespread application is hindered by their low substrate adhesion and weak static antifouling capabilities. In this study, a novel silicone polymer polydimethylsiloxane (PDMS)-based poly(urea-thiourea-imine) (PDMS-PUTI) was synthesized via stepwise reactions of aminopropyl-terminated polydimethylsiloxane (APT-PDMS) with isophorone diisocyanate (IPDI), isophthalaldehyde (IPAL), and carbon disulfide (CS2). Subsequently, a nanocomposite coating (AgNPs-x/PDMS-PUTI) was prepared by adding silver nanoparticles (AgNPs) to the polymer PDMS-PUTI. The dynamic multiple hydrogen bonds formed between urea and thiourea linkages, along with dynamic imine bonds in the polymer network, endowed the coating with outstanding self-healing properties, enabling complete scratch healing within 10 min at room temperature. Moreover, uniformly dispersed AgNPs not only reduced the surface energy of the coating but also significantly enhanced its antifouling performance. The antibacterial efficiency against common marine bacteria Pseudomonas aeruginosa (P.sp) and Staphylococcus aureus (S.sp) was reduced by 97.08% and 96.71%, respectively, whilst the diatom settlement density on the coating surface was as low as approximately 59 ± 3 diatom cells/mm2. This study presents a novel approach to developing high-performance silicone antifouling coatings.

Humidity-responsive pectin/AgNPs/ZnO composite films with high antimicrobial and UV-proof functions.

ZnO nanoparticles and Ag nanoparticles (AgNPs) tend to agglomerate when used individually, and high Ag+concentrations can cause cytotoxicity. To address these issues, we synthesized carboxymethyl cellulose (CMC)-based antimicrobial mimetic peptides (AMPMs) by introducing amphiphilic cations on the surface of CMC using a chemical grafting method. Bis-formaldehyde-formylated AMPMs were prepared through the directional oxidation of AMPMs with periodate and used as the reducing agent to synthesize AgNPs on the surface of pectin in situ for the preparation of a pectin/AgNPs/ZnO composite film. The physical and chemical properties of the films were characterized and analyzed by SEM (EDS), TEM, XRD, and UV spectroscopy. The results showed that the film's surface was smooth and flat, with small, well-stabilized AgNPs and uniformly dispersed ZnO. The film retained the original crystalline form of pectin, but exhibited altered crystallinity, indicating that the method employed was very mild. A systematic evaluation of the film's antimicrobial performance using the dynamic growth curve, inhibition zone, and colony counting methods showed that AgNPs and ZnO imparted excellent, long-lasting antimicrobial activity to the film (98 %). Additionally, the films exhibited good flexibility, excellent ultraviolet protection (99.9 %), biocompatibility, and biodegradability. Notably, the film was sensitive to humidity, as demonstrated by its humidity-responsive bionic application. This study provides a promising reference and strategy for advancing the development of multifunctional polysaccharide-based nanocomposites.

Can acclimation of freshwater rotifers to silver nanoparticles or 5-fluorouracil influence their multi- and transgenerational effects?

Emerging chemical contaminants (ECCs) are among the major environmental threats in present century. A variety of ECCs is released into aquatic environments with little knowledge about their long-term impacts to organisms. We examined the role of acclimation of the freshwater rotifer Brachionus calyciflorus to silver nanoparticles (Ag-NPs) and 5-fluorouracil (5-FU) for determining their ability to deal with these ECCs individually and in mixtures along multiple generations. Additionally, transgenerational effects were also assessed during the recovery phase. Rotifers acclimated at EC10 of Ag-NPs along generations showed a higher ability to deal with higher concentrations of these nanoparticles or 5-FU along generations. Rotifers acclimated to EC10 of 5-FU showed varied responses, as their population growth rates were affected at the initial generations once exposed to higher concentration (EC50) of the same or a new contaminant; however, the rotifers acquired resistance in later generations. The exposure of generational Ag-NP-acclimated rotifers to the mixture of Ag-NPs and 5-FU at EC50 led to a shift from no effects to negative effects along successive generations, suggesting a decrease in resistance, which remained even in the post-exposure recovery phase. Similar transgenerational adverse effects were also observed for the generational Ag-NP-acclimated rotifers released from 5-FU. Rotifers acclimated to 5-FU showed a decrease in population growth rate at the first generation of recovery phase, possibly shifting their optimal environmental conditions when released from contaminants. Overall, our results suggest that rotifers had a high level of plasticity to ECC exposure in freshwaters; however, acclimation can be generic or contaminant dependent.

Preparation of chitosan/polyvinyl alcohol antibacterial indicator composite film loaded with AgNPs and purple sweet potato anthocyanins and its application in strawberry preservation.

This study incorporated purple sweet potato anthocyanin (PSPA) and silver-nanoparticles (AgNPs) into the chitosan/polyvinyl alcohol film matrix (PVA/CS) to successfully prepare a composite film, which effectively inhibited bacterial growth and indicated product freshness. The addition of AgNPs and PSPA led to a dense structure of the film, which effectively enhanced its physical properties, barrier properties and functional properties. The incorporation of PSPA made the composite film highly pH-sensitive, which exhibited distinct color changes in varying pH solutions. The PVA/CS-AgNPs-PSPA10 composite film with PSPA and AgNPs resulted the shelf life of strawberries to 13 days at 4 °C, which effectively reduced strawberry breathing during storage. Additionally, such composite film changed color from purple to yellow-purple, indicating the deterioration of strawberries. It also showed an antibacterial indication through its excellent antibacterial property and freshness indication performance, which demonstrated its significance in developing antibacterial indicator composite packaging materials for fruits and vegetables preservation.

Incorporating nanosilver with glass ionomer cement-A literature review.

OBJECTIVES: The objectives of this study were to retrieve and review studies that incorporated nanosilver with GIC and summarise the evidence regarding the properties of nanosilver-modified GIC. MATERIALS AND METHODS: Two independent researchers performed a literature search using the keywords (nanosilver OR nano-silver OR (nano silver) OR (silver nanoparticles)) AND (GIC OR (glass ionomer cement) OR (glass ionomer cements)) in PubMed, Web of Science and ScienceDirect. RESULTS: A total of 368 articles were identified. After removing duplicate results, titles and abstracts were screened for eligibility. Full texts of publications that investigated the manufacture and properties of nanosilver-modified GIC were retrieved and analysed. Finally, 21 studies were included. CONCLUSIONS: All of the studies reviewed in this investigation included the incorporation of nanosilver in GIC. The proportions of nanosilver added into GIC varied from 0.05 % to 50 %. Thirteen studies investigated the antimicrobial properties of nanosilver-modified GIC; all studies supported that adding nanosilver enhanced antimicrobial effectiveness. Nineteen studies reported the mechanical properties including compressive strength, flexure strength, tensile strength, and microhardness of nanosilver-modified GIC; but the results were inconclusive. Four studies tested the bonding strength of nanosilver-modified GIC to dentine and found that adding nanosilver would not influence the bonding property of GIC. Some studies explored fluoride release level, colour stability, and cytotoxicity of nanosilver-modified GIC; but the results were all inconclusive. CLINICAL SIGNIFICANCE: This literature review is the first study to retrieve and summarise the findings and evidence regarding nanosilver-modified GIC research. It can provide clinicians with clinically relevant information about novel GIC materials that can be used in their treatment decisions.

Antifungal mechanism of nanosilver biosynthesized with Trichoderma longibrachiatum and its potential to control muskmelon Fusarium wilt.

Fusarium oxysporum (Schl.) f.sp. melonis, which causes muskmelon wilt disease, is a destructive filamentous fungal pathogen, attracting more attention to the search for effective fungicides against this pathogen. In particular, Silver nanoparticles (AgNPs) have strong antimicrobial properties and they are not easy to develop drug resistance, which provides new ideas for the prevention and control of muskmelon Fusarium wilt (MFW). This paper studied the effects of AgNPs on the growth and development of muskmelon, the control efficacy on Fusarium wilt of muskmelon and the antifungal mechanism of AgNPs to F. oxysporum. The results showed that AgNPs could inhibit the growth of F. oxysporum on the PDA and in the PDB medium at 100-200 mg/L and the low concentration of 25 mg/L AgNPs could promote the seed germination and growth of muskmelon seedlings and reduce the incidence of muskmelon Fusarium wilt. Further studies on the antifungal mechanism showed that AgNPs could impair the development, damage cell structure, and interrupt cellular metabolism pathways of this fungus. TEM observation revealed that AgNPs treatment led to damage to the cell wall and membrane and accumulation of vacuoles and vessels, causing the leakage of intracellular contents. AgNPs treatment significantly hampered the growth of mycelia in the PDB medium, even causing a decrease in biomass. Biochemical properties showed that AgNPs treatment stimulated the generation of reactive oxygen species (ROS) in 6 h, subsequently producing malondialdehyde (MDA) and increasing protective enzyme activity. After 6 h, the protective enzyme activity decreased. These results indicated that AgNPs destroy the cell structure and affect the metabolisms, eventually leading to the death of fungus.

Green synthesis of silver nanoparticles from Brassaiopsis hainla extract for the evaluation of antibacterial and anticorrosion properties.

Plant-mediated synthesis of silver nanoparticles (AgNPs) is an eco-friendly and convenient alternative to conventional methods. Brassaiopsis hainla (B. hainla) leaf extract (BHE) was used in this study to reduce metal salts and cap and stabilize nanoparticles (NPs), which were characterized and tested for antibacterial and anti-corrosion properties. Stirring the B. hainla extract with AgNO3 led to a color change, indicating nanoparticle formation. The absorption peak at 428 nm in the UV-visible spectrum further validated its formation. The AgNPs were characterized using various techniques such as FTIR, UV-visible, PXRD, HRTEM, SEM, and EDX. Powder X-ray diffraction analysis confirmed its nanocrystalline nature, with an average crystallite size of 17.92 nm. The FTIR spectrum showed hydroxyl, amine, amide, and carbonyl groups as capping and reducing agents for the AgNPs. SEM analysis revealed poly-dispersed NPs of various sizes, while EDX showed an intense peak for Ag, and TEM images revealed mostly hexagonal and triangular NPs. Antibacterial activity was tested against three human pathogens: Staphylococcus aureus (S. aureus), Pseudomonas, and Klebsiella oxytoca (K. oxytoca). Significant antibacterial activity was observed specifically against K. oxytoca, with an 11 mm inhibition zone. Both plant extracts and AgNPs inhibited acid-induced corrosion, with the highest inhibition efficiencies of 81.69 % and 69.54 % at 1000 ppm, respectively. With rising concerns over bacterial resistance and metal corrosion, this study addresses global challenges related to new antimicrobial agents, which are crucial for combating antibiotic resistance and protecting metals in various industries.