Attachment Of AgNPs Research Articles

Antiviral Activity of Graphene Oxide-Silver Nanocomposites Against Murine Betacoronavirus.

The high infectivity of coronaviruses has led to increased interest in developing new strategies to prevent virus spread. Silver nanoparticles (AgNPs) and graphene oxide (GO) have attracted much attention in the antiviral field. We investigated the potential antiviral activity of GO and AgNPs combined in the nanocomposite GO-Ag against murine betacoronavirus MHV using an in vitro model. GO, AgNPs, and GO-Ag characterization (size distribution, zeta potential, TEM visualization, FT-IR, and EDX analysis) and XTT assay were performed. The antiviral activity of GO-Ag nanocomposites was evaluated by RT-qPCR and TCID50 assays. The results were compared with free AgNPs and pure GO. Cell growth and morphology of MHV-infected hepatocytes treated with GO-Ag composites were analyzed by JuLI™Br. Immunofluorescence was used to visualize the cell receptor used by MHV. Ultrastructural SEM analysis was performed to examine cell morphology after MHV infection and GO-Ag composite treatment. A significant reduction in virus titer was observed for all nanocomposites tested, ranging from 3.2 to 7.3 log10 TCID50. The highest titer reduction was obtained for GO 5 µg/mL - Ag 25 µg/mL in the post-treatment method. These results were confirmed by RT-qPCR analysis. The results indicate that GO-Ag nanocomposites exhibited better antiviral activity compared to AgNPs and GO. Moreover, the attachment of AgNPs to the GO flake platform reduced their cytotoxicity. In addition, the GO-Ag composite modulates the distribution of the Ceacam1 cell receptor and can modulate cell morphology. Graphene oxide sheets act as a stabilizing agent, inhibiting the accumulation of AgNPs and reducing their cellular toxicity. The GO-Ag composite can physically bind and inhibit murine betacoronavirus from entering cells. Furthermore, the constant presence of GO-Ag can inhibit MHV replication and significantly limit its extracellular release. In conclusion, GO-Ag shows promise as an antiviral coating on solid surfaces to minimize virus transmission and spread.

Silver Nanoparticle/Carbon Nanotube Hybrid Nanocomposites: One-Step Green Synthesis, Properties, and Applications.

Hybrid nanocomposites of silver nanoparticles and multiwalled carbon nanotubes (AgNPs/MWCNTs) were successfully synthesized by a green one-step method without using any organic solvent. The synthesis and attachment of AgNPs onto the surface of MWCNTs were performed simultaneously by chemical reduction. In addition to their synthesis, the sintering of AgNPs/MWCNTs can be carried out at room temperature. The proposed fabrication process is rapid, cost efficient, and ecofriendly compared with multistep conventional approaches. The prepared AgNPs/MWCNTs were characterized using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The transmittance and electrical properties of the transparent conductive films (TCF_Ag/CNT) fabricated using the prepared AgNPs/MWCNTs were characterized. The results showed that the TCF_Ag/CNT film has excellent properties, such as high flexible strength, good high transparency, and high conductivity, and could therefore be an effective substitute for conventional indium tin oxide (ITO) films with poor flexibility.

Neutrally charged nanosilver antimicrobial effects: A surface thermodynamic perspective

Nanosilver (AgNP) has a large surface area that contributes to enhanced interactions with bacteria, as well as silver ion release. The actual AgNP antimicrobial effect is determined by the AgNP size. AgNPs with smaller diameters showed better antimicrobial effects because smaller AgNPs had larger surface areas, which led to greater silver ion release and stronger attachment to bacteria. The attachment of AgNPs to bacterial surfaces is attributed to the attractive interactions between the AgNPs and bacteria, which is also a function of the size of AgNPs. Although the antimicrobial activity of AgNPs has been extensively studied, there is a gap between antimicrobial effects of AgNPs on bacteria and their subsequent attachment. To fully understand the antimicrobial effectiveness of different-sized AgNPs, this study investigated the dynamic process of AgNP-bacteria interactions in aqueous media, including AgNP aggregation, AgNP attachment, and antimicrobial effects. AgNP-AgNP and AgNP-bacteria interactions were quantified based on DLVO and surface chemistry theories, which were used to interpret subsequent AgNP aggregation, AgNP-bacteria attachment and AgNP antimicrobial observations.

Laser-scribed graphene nanofiber decorated with oil palm lignin capped silver nanoparticles: a green biosensor

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), requires a high level of attention and is one of the most infectious diseases in the air. Present methods of diagnosing TB remain ineffective owing to their low sensitivity and time consumption. In this study, we produced a green graphene nanofiber laser biosensor (LSG-NF) decorated with oil palm lignin-based synthetic silver nanoparticles (AgNPs). The resulting composite morphology was observed by field-emission scanning electron microscopy and transmission electron microscopy, which revealed the effective adaptation of the AgNPs to the LSG-NF surface. The successful attachment of AgNPs and LSG-NFs was also evident from X-ray diffraction and Raman spectroscopy studies. In order to verify the sensing efficiency, a selective DNA sample captured on AgNPs was investigated for specific binding with M.tb target DNA through selective hybridisation and mismatch analysis. Electrochemical impedance studies further confirmed sensitive detection of up to 1 fM, where a detection limit of 10−15 M was obtained by estimating the signal-to-noise ratio (S/N = 3:1) as 3σ. Successful DNA immobilisation and hybridisation was confirmed by the detection of phosphorus and nitrogen peaks based on X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The stability and repeatability of the analysis were high. This approach provides an affordable potential sensing system for the determination of M. tuberculosis biomarker and thus provides a new direction in medical diagnosis.

Modified polystyrene spheres/graphene oxide decorated with silver nanoparticles as bactericidal material

This work describes the preparation of a composite material consisting of Graphene oxide (GO) nanosheets impregnated with silver nanoparticles (AgNPs) synthesized by reduction in situ of adsorbed Ag+ by NaBH4 and over modified polystyrene spheres (PS). PS/GO-AgNPs water dispersion and its film deposited over a polymeric support were tested for their antibacterial activity. The PS/GO-AgNPs composite was characterized by UV–vis spectra, transmission electron microscopy, X-ray diffraction, and scanning electron microscopy. The results obtained by these techniques confirmed the formation of PS/GO composite, they also confirmed the attachment of AgNPs to the GO sheets. The antibacterial activity of this composite was evaluated in seven different bacteria. PS/GO-AgNPs composite performed efficiently in bringing down the count of Bacilus cereus, Escherichia coli, Pseudomonas aeroginosa, Aeromonas hydrophila and Salmonella typhimurium from 106 cfu mL-1 to zero with 200 mg L-1 of PS/GO-AgNPs in water. Results from inhibition halo showed that films containing PS/GO-AgNPs have inhibited the growth of all microbial species in the same magnitude compared to GO-AgNPs. The water dispersed PS/GO-AgNPs composite enabled them to be easily deposited on surfaces, for example, walls or floors in contaminated environments present in hospitals, by a simple spray method to act as a biocidal material, avoiding the undesirable presence of nanoparticle materials (GO-AgNPs) suspended on air.

Diatomite encapsulated AgNPs as novel hair dye cosmetics: Preparation, performance, and toxicity

Naturally-occurring diatomite has been successfully utilised as a unique encapsulating material to obtain a highly dispersed suspension of uniformly-sized silver nanoparticles (AgNPs). Plant derived gallic acid was used as the reducing and capping agent. High-resolution scanning and transmission electron microscopy results confirmed the attachment of AgNPs on the surface of diatom frustule and maintained an excellent dispersion stability against particle aggregation. The AgNPs obtained were employed for the colouration of bleached human hair owing to the local surface plasmonic absorption (LSPR) of the AgNPs. The effects of Ag/diatomite concentration, dyeing pH, temperature and time on the produced colour were investigated. Hair fibres treated under optimised conditions display good colour fastness toward solar radiation. The morphology and chemical composition of AgNP-dyed hair were determined by energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses. The biocompatibility of the Ag/diatomite composite, AgNPs, and the dyebaths were confirmed by in vitro acute dermal and ocular toxicity tests. The diatomite supporting AgNPs therefore hold good promise and enormous potential to be exploited for sustainable dyeing of human hair.

Surface modification via silver nanoparticles attachment: An ex-situ approach for enhancing the electron field emission properties of CNT field emitters

A novel one-dimensional carbon material Known as carbon nanotubes (CNTs), having their high aspects ratio and as well as advance electrical properties which make them best candidate for cathode field emitters. In this work, we have introduced the easy and cost-effective approach to improving the CNT field emitters emission properties. Here we have modified the surface of CNT field emitter via decorating with silver nanoparticles (Ag NPs). Attachment of Ag NPs on CNT surface via thermal evaporation technique. The as-prepared samples of pristine CNTs and decorated CNTs with Ag NPs were characterized by the scanning electron microscope for morphology analysis, quality and qualitative analysis done by Raman spectroscopy. Here we have applied the Fowler Nordheim hypothesis for the analysis of electron field emission of as-prepared cathode field emitters. The turn-on (Eto) and threshold (Eth) field reduced after CNT field emitters coated with Ag NPs. The field enhancement factor (β) and emission current density (J) enhanced after coating. Ag NPs decorated/coated CNT field emitters can be utilized in field emission device applications.

One pot synthesis of silver nanoparticles on ITO surfaces: investigation of optical and electrochemical properties

Dense layer of silver nanoparticles (AgNPs) was successfully prepared on indium tin oxide (ITO) surfaces by using a refined seed-mediated growth approach (RSMG). Prepared AgNPs/ITO film was investigated using several methods such as UV–vis spectroscopy, field emission scanning electron microscope, optical absorption, electrochemical impedance spectroscopy and cyclic voltammeter. The size and density of AgNPs on ITO surface were investigated and their governing parameters were discussed. The obtained results by using refined seed-mediated growth approach showed a narrower size distribution and a higher density of prepared AgNPs compared to those prepared by the normal seed-mediated growth method. The size of AgNPs was controlled by adjusting the growth time until 2 h, while if it is higher than 3 h, larger AgNPs with anisotropic shape were formed. Cysteamine molecules were used to ensure the attachment of AgNPs on the ITO surface and it was found to be effective for preparing dense and dispersed Ag NPs on ITO surface. The optical properties of prepared AgNPs layer with different density on the ITO surface were studied and discussed, using the full Mie theory for scattering and absorption by a homogeneous Ag sphere with modified dielectric constants.

Laser Functionalization of Carbon Membranes for Effective Immobilization of Antimicrobial Silver Nanoparticles

Abstract Microbial contamination and biofilm formation are serious challenges in water filtration applications. Recently, carbon nanocomposite membranes with modified silver nanoparticles (AgNPs) have attracted much attention as compelling water purification membranes that can deactivate pathogenic bacteria and prevent biofilm formation. However, the effective attachment of AgNPs onto such carbon-based surfaces has proven difficult to accomplish via inexpensive and rapid fabrication processes. In this study, we introduce a simple laser-assisted process that enables rapid surface functionalization and immobilization of AgNPs onto carbon cloth membrane surfaces comprised of woven carbon micro fibers. The laser functionalization provides a unique modification in surface morphology of the fibers by creating nanotextures as well as inducing changes in surface chemistry, all of which increase the physical and chemical bonding of AgNPs onto the surface of carbon fibers. Elemental and surface morphology analysis via XRD, SEM, and EDX reveal a uniform coating and strong attachment of AgNPs onto the laser functionalized carbon surface, even after vigorous mechanical agitations and probe sonication. The analysis showed the samples prepared by the laser functionalization prior to AgNPs coating provided exceptional antibacterial activity and ability to completely eradicate the bacteria within 4 h and resist biofilm formation against pathogenic bacterial strains of Escherichia coli. The developed technology provides new opportunities to develop a scalable, fast, and cost-effective preparation method for producing carbon-based materials/membranes with high antimicrobial activities which can be applied for water purification and other environmental applications.

A green deposition method of silver nanoparticles on textiles and their antifungal activity

This study aims to propose a new green method for the deposition of silver nanoparticles (AgNPs) on textiles without the use of chemical compounds as binders. The deposition of AgNPs on textiles was achieved by immersing textiles in silver nitrate solution before adding with a natural reducing agent obtained from the extraction of Mikania micrantha. Plasmonic properties of the synthesized AgNPs were characterized using Ultraviolet-visible (UV–vis) spectroscopy and surface morphology of textiles was identified using the field-emission scanning electron microscopy (FESEM). In addition, energy-dispersive X-ray spectroscopy was also employed for the characterization. Inhibition zone measurement was performed for evaluating the antifungal capability of textiles attached with AgNPs. This study showed that the attachment of AgNPs to several textile types (cotton, cotton-polyester, silk, and fiber) without the use of binders or other chemical compounds had been successfully achieved. Moreover, all textiles attached with AgNP exhibited effective antifungal activity.

Distinct mechanisms in the heteroaggregation of silver nanoparticles with mineral and microbial colloids

Attachment to solids is an important process for determining nanomaterial transport and their fate in environments. Here we revealed distinct behaviours in the attachment of silver nanoparticles (AgNPs) to kaolin and bacterial cells. We found preferential attachment of AgNPs to the edges of kaolin. Decreasing pH or adding metal ions promoted AgNP-kaolin attachment due to the increase of positive charge on kaolin’s surfaces. Multivalent cations (Mg2+ and Ca2+) induced stronger enhancement than monovalent cations (Na+, K+ and Ag+), which demonstrated the positive role of electrostatic interaction in AgNP-kaolin attachment. However, the presence of metal ions inhibited AgNP binding to bacterial cells. The inhibitive effect was significantly correlated with solubility product of metal ions, which implied a chemical reaction mechanism in AgNP-cell attachment. In kaolin system, humic acid (HA) can considerably inhibit AgNP attachment and diminish the enhanced effects induced by metal ions. In contrast, in bacterial cell system, HA reduced the inhibitive effect of metal ions for AgNP adsorption, although HA itself had negligible effect on AgNP-cell attachment. Taken together, our results demonstrated the contribution of electrostatic attraction versus chemical interaction to the attachment of AgNPs to kaolin or bacterial cells, providing fundamental support to understand the attachment of nanomaterials to inorganic and organic solids in the environments.

Toxicity of silver nanoparticles to green algae M. aeruginosa and alleviation by organic matter.

Silver nanoparticles (AgNPs) have been increasingly used in a wide range of consumer products over the last decade. The release of AgNPs into aquatic ecosystems raises concerns about their safety and environmental toxicity, which have been the subject of recent studies. Herein, we assess the toxicity of AgNPs to the common algae Microcystis. aeruginosa. A toxicological response by M. aeruginosa was exhibited at an early stage of exposure to AgNPs, which were also toxic to its growth, photosynthetic, and membrane systems. The attachment of AgNPs to microalgae is likely the main mechanism by which it damages cell membranes. Dissolved Ag ions, originating from internalized AgNPs, seem to directly target the photosynthetic system. We also found that several humus-related indicators of water quality (HIX and β/α) were related to reduced AgNPs toxicity. Graphical abstract.

Effect of Acid Treatment on Activated Carbon: Preferential Attachment and Stronger Binding of Metal Nanoparticles on External Carbon Surface, with Higher Metal Ion Release, for Superior Water Disinfection

For ensuring complete, high-throughput disinfection of water, superior interaction of silver nanoparticles (Ag-NPs) with contaminating E. coli cells in water is crucial. This is achieved by preferential attachment of Ag-NPs on the outer surface of activated carbon (AC), by either plasma or acid treated AC samples, termed as Ag-p-AC and Ag-a-AC hybrids, respectively. In subsequent flow-column experiments, Ag-a-AC showed 4 log reduction in E. coli cells in only 14 min of residence-time, which is much less compared to Ag-p-AC (23 min). This enhanced performance is due to (i) attachment of more Ag-NPs on the outer surface of Ag-a-AC, providing better dispersion of individual Ag-NPs and (ii) altered surface topography of acid-treated AC, due to its higher surface roughness (increasing from 15.29 pm to 1.15 nm on acid treatment). The latter leads to release of more Ag+ ions and, therefore, faster E. coli death in flow-column. Furthermore, Ag-NPs were much more strongly bonded to acid treated AC (944 kJ/mol adso...

Bio-inspired immobilization of casein-coated silver nanoparticles on cellulose acetate membranes for biofouling control

This study shows the results of low-biofouling nanocomposite membranes, loaded with casein-coated silver nanoparticles (casein-Ag-NPs). Membranes were cast and imbedded with Ag-NPs using two approaches, physical blending of Ag-NPs in the dope solution (PAg-NP/CA membranes) and chemical attachment of Ag-NPs to cast membranes (CAg-NP/CA membranes), to determine their biofouling control properties. The functionalization of Ag-NPs onto the CA membranes was achieved via attachment with functionalized thiol groups with the use of glycidyl methacrylate (GMA) and cysteamine chemistries, which was inspired by the affinity of silver to the thiol groups of cysteine proteins in bacteria. The immobilization chemistry successfully prevented leaching of silver nanoparticles during cross-flow studies. Pseudomonas fluorescens Migula in brackish water was used for dead-end filtration, where CAg-NP/CA membranes displayed lower a significant reduction in the accumulation of bacterial cells, likely due to the more dispersed nanoparticles across the surface.

Non-Enzymatic Electrochemical Detection of Urea on Silver Nanoparticles Anchored Nitrogen-Doped Single-Walled Carbon Nanotube Modified Electrode

Herein, we demonstrated synthesis and application of silver nanoparticles (Ag-NPs) decorated nitrogen doped single-walled carbon nanotube through a one-step thermal-reduction method using melamine as the nitrogen source. Field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction data confirmed the successful synthesis of Ag-NPs functionalized nitrogen doped single-walled carbon nanotubes(Ag-N-SWCNTs). The nitrogen-doping notably modified the properties of the SWCNT and it showed stronger affinity for the attachment of Ag-NPs. By integrating the high surface area and electrical properties of N-SWCNTs with Ag-NPs, the obtained Ag-N-SWCNTs nanocomposite showed high catalytic activity than N-SWCNTs and pristine-SWCNTs. The enzyme-based methods have some disadvantages. For example, high fabrication cost and poor stability, due to these intrinsic disadvantages, non-enzymatic sensors have received more interest in fabrication of sensors. A non-enzymatic electrochemical urea sensor was developed by modifying glassy carbon electrode (GCE) with Ag-N-SWCNTs and a layer of Nafion (Nf). Thus, the fabricated sensor exhibited lower limit of detection (4.7 nM), with an enhanced sensitivity of 141 μAmM−1cm−2 for urea detection in the range of 66 nM to 20.6 mM(R2 = 0.966). The reliability of the as-fabricated sensor was successfully investigated by using it to detect urea in tap water and milk samples. The NF/Ag-N-SWCNTs based urea sensor offers several advantages such as simple fabrication procedure, non-enzymatic and low-cost, so this sensor can be applied to detect urea in various samples from food, fertilizer industries and environmental fields. Moreover, the modified electrode showed phenomenal stability with no loss in activity of storage under ambient conditions. In addition, the novel hybrid NF/Ag-N-SWCNTs/GCE showed high selectivity toward urea with good repeatability and reproducibility further confirmed that this method can be utilized for detection of urea.

Development of Synergistic Antimicrobial Coating of p-Aramid Fibers Using Ag Nanoparticles and Glycidyltrimethylammonium Chloride (GTAC) without the Aid of a Cross-Linking Agent.

Functional p-aramid fibers that can express antimicrobial activity were produced by simple processing of silver nanoparticles (AgNPs), which are well known as antimicrobial agents, by using glycidyltrimethylammonium chloride (GTAC), a quaternary ammonium salt. P-aramid fibers were treated with GTAC by the pad-dry-cure process and put into an Ag colloid solution for reactions at 40 °C for 90 min to prepare GTAC/AgNPs-treated p-aramid fibers. Through these processes, GTAC was used as a substitute for existing cross-linking agents. The changes in the degree of attachment of AgNPs to the surface of p-aramid fibers were determined using a scanning electron microscope according to parameters such as GTAC concentration, Ag colloid concentration, and reaction temperature. Through this study, the following results were obtained: (i) The tensile strength of AgNPs/GTAC-treated p-aramid fibers was found to be about 80% of that of untreated p-aramid fibers; (ii) Thermogravimetric analysis showed that the thermal stability of p-aramid fibers did not change much after GTAC/AgNPs treatment and (iii) Antimicrobial activity analysis showed that AgNPs/GTAC-treated p-aramid fibers exhibited superior antibacterial properties compared to untreated p-aramid fibers, which may or may not be the effect of GTAC or AgNPs, or both.

Silver nanoparticles supported on carbon nanotube carpets: influence of surface functionalization

The effectiveness of nanoparticle-based functional devices depends strongly on the surface morphology and area of the support. An emerging powerful approach of increasing the available surface area without decreasing strength or increasing bulk is to attach arrays of suitable nanotubes on the surface, and to attach the necessary nanoparticles to them. Earlier publications by this team have shown that carpet-like arrays of carbon nanotubes (CNTs) can be successfully grown on a variety of larger carbon substrates such as graphite, foams and fabric, which offer hierarchical multiscale supporting architecture suitable for the attachment of silver nanoparticles (AgNPs). A limiting factor of pure CNT arrays in fluid-based applications is their hydrophobicity, which can reduce the percolation of an aqueous medium through individual nanotubes. Previous studies have demonstrated that the treatment of CNT carpets with dry (oxygen) plasma can induce reversible wettability, and treatment with wet (sol–gel) coating can impart permanent wettability. In this paper, we report the influence of such treatments on the attachment of AgNPs, and their effectiveness in water disinfection treatments. Both types of hydrophilic surface treatment show an increase in silver loading on the CNT carpets. Oxygen-plasma treated surfaces (O-CNT) show fine and densely packed AgNPs, whereas silica-coated nanotubes (silica-CNT) show uneven clusters of AgNPs. However, O-CNT surfaces lose their hydrophilicity during AgNP deposition, whereas silica-CNT surfaces remain hydrophilic. This difference significantly impacts the antibacterial effectiveness of these materials, as tested in simulated water containing Gram negative Escherichia coli (E. coli, JM109). AgNPs on silica-coated CNT substrates showed significantly higher reduction rates of E. coli compared to AgNPs on plasma-treated CNT substrates, despite the finer and better dispersed AgNP distribution in the latter. These results provide important insights into different aspects of surface modification approaches that can control the wettability of CNT carpets, and their applicability in water treatment applications.

Potential enhancement of antibacterial activity of graphene oxide-silver nanocomposite by introducing C2 carbon chain linkage

Various carbon chain linkages were introduced during the process of synthesizing silver-nanoparticles (AgNPs)-decorated graphene nanocomposites [referred to as GO-Cx-Ag where, HS-(CH2)x-SH=Cx and x=0, 2, or 4] to evaluate antibacterial properties. The nano-structures of GO-Cx-Ag were characterized using TEM and XPS, revealing that GO-C2-Ag comprises well-dispersed and smaller AgNPs anchored onto the surface of graphene sheets than the GO-C0-Ag and GO-C4-Ag. The antibacterial activities of those nanocomposites were assessed using paper-disk diffusion and minimal inhibitory concentration (MIC) methods against Gram-negative and Gram-positive bacteria. The results showed that carbon chain linkers enhanced the antibacterial activity against Gram-negative Salmonella typhimurium and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. In particular, GO-C2-Ag showed higher antibacterial activity than GO-C0-Ag and GO-C4-Ag due to nearly eight times higher reactive oxygen species (ROS) formation which determined by fluorescence-based ROS detection experiment. Also, LC-inductively coupled plasma mass spectrometer (LC-ICP-MS) demonstrated that the Ag release from GO-Cx-Ag was insignificant (0.03%). However, the higher ROS formation from GO-C2-Ag was facilitated by higher dispersion, smaller size, and well attachment of AgNPs with AgO species onto graphene sheets. These results suggest that the medium length carbon chain linkers in between Ag and GO can be utilized to improve antibacterial activity.

Core–satellite ZnS–Ag nanoassemblies: Synthesis, structure, and optical properties

We synthesized hollow core–satellite nanoassemblies comprised of hollow zinc sulfide (ZnS) shells decorated with silver nanoparticles (Ag NPs). This was achieved by solution-phase attachment of Ag NPs to hollow ZnS nanospheres (NSs) prepared by spray pyrolysis. This produces an aqueous dispersion of ZnS–Ag hybrid structures, 50–500nm in overall diameter. We characterized the nanostructures by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX) to elucidate the ZnS (core)–Ag (satellite) morphology and optimize conditions for producing such structures. Optical spectroscopy showed that photoluminescence of ZnS was quenched by Ag while absorbance was enhanced. This work provides a simple and general means of producing hollow core–satellite structures that could be of broad applicability.

Antimicrobial effects of chitosan silver nano composites (CAgNCs) on fish pathogenic Aliivibrio (Vibrio) salmonicida

Chitosan is one of the promising bio-degradable natural products which can be applied in nano forms in disease prevention, and treatment measures in aquaculture. The aim of this study was to develop and investigate the antibacterial function of chitosan-silver nano composites (CAgNCs) against fish pathogenic Aliivibrio salmonicida. Zeta potential and average size of synthesized CAgNCs were +32.1mV and 281nm, respectively. The Ag content of the CAgNCs was 0.643±0.012% (w/w). Antibacterial results revealed that CAgNCs could inhibit the A. salmonicida growth which indicates minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) at 50μg/mL and 100μg/mL, respectively. We confirmed the attachment of AgNPs on the surface of A. salmonicida which indicates the interaction of CAgNCs with the bacterium. Propidium iodide (PI) uptake results suggested that CAgNCs has affected to permeability of cell membrane of A. salmonicida. Also, CAgNCs induced the level of reactive oxygen species (ROS) in concentration and time dependent manner (up to 3h) suggesting that it may generate oxidative stress leading to bacterial cell death. Also, the level of protein was decreased in A. salmonicida cells after CAgNCs (50μg/mL) treatment. DNA fragmentation assay results confirmed that CAgNCs can cause extensive DNA degradation of A. salmonicida which may inhibit the expression and production of bacterial proteins. Toxicity and safety results prove that CAgNCs is not toxic to zebrafish (Danio rerio) at 12.5mg/kg of body weight/day as a feed ingredient and rock bream (Oplegnathus fasciatus) testis cells up to 50μg/μL. Overall results from this study suggest that CAgNCs is potential antibacterial agent to control fish pathogenic bacteria. Statement of relevanceThe fisheries and aquaculture industry can be optimized by using biodegradable nano materials such as chitosan for disease detection, control as well as delivery system of drugs such as hormones, vaccines and nutrients.Aquaculture can be optimized by using biodegradable nano materials such as chitosan for disease detection, control as well as delivery system of drugs such as hormones, vaccines and nutrients.Application of biodegradable nano materials in aquaculture