Displaying publications 101 - 120 of 131 in total

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  1. Green synthesis of graphene-silver nanocomposites and its application as a potent marine antifouling agent
    Yee MS, Khiew PS, Chiu WS, Tan YF, Kok YY, Leong CO
    Colloids Surf B Biointerfaces, 2016 Dec 01;148:392-401.
    PMID: 27639489 DOI: 10.1016/j.colsurfb.2016.09.011
    Fouling of marine surfaces has been a perpetual problem ever since the days of the early sailors. The tenacious attachment of seaweed and invertebrates to man-made surfaces, notably on ship hulls, has incurred undesirable economic losses. Graphene receives great attention in the materials world for its unique combination of physical and chemical properties. Herein, we present a novel 2-step synthesis method of graphene-silver nanocomposites which bypasses the formation of graphene oxide (GO), and produces silver nanoparticles supported on graphene sheets through a mild hydrothermal reduction process. The graphene-Ag (GAg) nanocomposite combines the antimicrobial property of silver nanoparticles and the unique structure of graphene as a support material, with potent marine antifouling properties. The GAg nanocomposite was composed of micron-scaled graphene flakes with clusters of silver nanoparticles. The silver nanoparticles were estimated to be between 72 and 86nm (SEM observations) while the crystallite size of the silver nanoparticles (AgNPs) was estimated between 1 and 5nm. The nanocomposite also exhibited the SERS effect. GAg was able to inhibit Halomonas pacifica, a model biofilm-causing microbe, from forming biofilms with as little as 1.3wt.% loading of Ag. All GAg samples displayed significant biofilm inhibition property, with the sample recording the highest Ag loading (4.9wt.% Ag) associated with a biofilm inhibition of 99.6%. Moreover, GAg displayed antiproliferative effects on marine microalgae, Dunaliella tertiolecta and Isochrysis sp. and inhibited the growth of the organisms by more than 80% after 96h. The marine antifouling properties of GAg were a synergy of the biocidal AgNPs anchored on the stable yet flexible graphene sheets, providing maximum active contact surface areas to the target organisms.
    Matched MeSH terms: Silver/chemistry*
  2. Fulltext In vitro molecular study of wound healing using biosynthesized bacteria nanocellulose/silver nanocomposite assisted by bioinformatics databases
    Moniri M, Boroumand Moghaddam A, Azizi S, Abdul Rahim R, Zuhainis SW, Navaderi M, et al.
    Int J Nanomedicine, 2018;13:5097-5112.
    PMID: 30254435 DOI: 10.2147/IJN.S164573
    Background: In recent years, bacterial nanocellulose (BNC) based nanocomposites have been developed to promote healing property and antibacterial activity of BNC wound dressing. Molecular study can help to better understanding about interaction of genes and pathways involved in healing progression.

    Objectives: The aim of this study was to prepare bacterial nanocellulose/silver (BNC/Ag) nanocomposite films as ecofriendly wound dressing in order to assess their physical, cytotoxicity and antimicrobial properties. The in vitro molecular study was performed to evaluate expression of genes involved in healing of wounds after treatment with BNC/Ag biofilms.

    Study design materials and methods: Silver nanoparticles were formed by using Citrullus colocynthis extract within new isolated bacterial nanocellulose (BNC) RM1. The nanocomposites were characterized using X-ray diffraction, Fourier transform infrared, and field emission scanning electron microscopy. Besides, swelling property and Ag release profile of the nanocomposites were studied. The ability of nanocomposites to promote wound healing of human dermal fibroblast cells in vitro was studied. Bioinformatics databases were used to identify genes with important healing effect. Key genes which interfered with healing were studied by quantitative real time PCR.

    Results: Spherical silver nanoparticles with particle size ranging from 20 to 50 nm were synthesized and impregnated within the structure of BNC. The resulting nanocomposites showed significant antibacterial activities with inhibition zones ranging from 7±0.25 to 16.24±0.09 mm against skin pathogenic bacteria. Moreover, it was compatible with human fibroblast cells (HDF) and could promote in vitro wound healing after 48h. Based on bioinformatics databases, the genes of TGF-β1, MMP2, MMP9, CTNNB1, Wnt4, hsa-miR-29b-3p and hsa-miR-29c-3p played important role in wound healing. The nanocomposites had an effect in expression of the genes in healing. Thus, the BNC/Ag nanocomposite can be used to heal wound in a short period and simple manner.

    Conclusion: This eco-friendly nanocomposite with excellent antibacterial activities and healing property confirming its utility as potential wound dressings.

    Matched MeSH terms: Silver/chemistry
  3. Enhanced photocatalysis and anticancer activity of green hydrothermal synthesized Ag@TiO2 nanoparticles
    Hariharan D, Thangamuniyandi P, Jegatha Christy A, Vasantharaja R, Selvakumar P, Sagadevan S, et al.
    J. Photochem. Photobiol. B, Biol., 2020 Jan;202:111636.
    PMID: 31739259 DOI: 10.1016/j.jphotobiol.2019.111636
    Titanium dioxide (TiO2) nanoparticles (NPs) have been doped with varying amounts (0.005, 0.010 and 0.015 M) of silver nanoparticles (Ag NPs) using hydrothermal method. Further, in this work, a green approach was followed for the formation of Ag@TiO2 NPs using Aloe vera gel as a capping and reducing agent. The structural property confirmed the presence of anatase phase TiO2. Increased peak intensity was observed while increasing the Ag concentration. Further, the morphological and optical properties have been studied, which confirmed the effective photocatalytic behavior of the prepared Ag@TiO2 NPs. The photocatalytic performance of Ag@TiO2 has been considered for the degradation of picric acid in the visible light region. The concentration at 0.010 M of the prepared Ag@TiO2 has achieved higher photocatalytic performance within 50 min, which could be attributed to its morphological behavior. Similarly, anticancer activity against lung cancer cell lines (A549) was also determined. The Ag@TiO2 NPs generated a large quantity of reactive oxygen species (ROS), resulting in complete cancer cell growth suppression after their systemic in vitro administration. Ag@TiO2 NPs was adsorbed visible light that leads to an enhanced anticancer sensitivity by killing and inhibiting cancer cell reproduction through cell viability assay test. It was clear that 0.015 M of Ag@TiO2 NPs were highly effective against human lung cancer cell lines and showed increased production of ROS in cancer cell lines due to the medicinal behavior of the Aloe vera gel.
    Matched MeSH terms: Silver/chemistry*
  4. Elastomeric biocomposite of silver-containing mesoporous bioactive glass and poly(1,8-octanediol citrate): Physiochemistry and in vitro antibacterial capacity in tissue engineering applications
    Pourshahrestani S, Zeimaran E, Kadri NA, Gargiulo N, Jindal HM, Hasikin K, et al.
    Mater Sci Eng C Mater Biol Appl, 2019 May;98:1022-1033.
    PMID: 30812986 DOI: 10.1016/j.msec.2019.01.022
    A novel series of silver-doped mesoporous bioactive glass/poly(1,8-octanediol citrate) (AgMBG/POC) elastomeric biocomposite scaffolds were successfully constructed by a salt-leaching technique for the first time and the effect of inclusion of different AgMBG contents (5, 10, and 20 wt%) on physicochemical and biological properties of pure POC elastomer was evaluated. Results indicated that AgMBG particles were uniformly dispersed in the POC matrix and increasing the AgMBG concentration into POC matrix up to 20 wt% enhanced thermal behaviour, mechanical properties and water uptake ability of the composite scaffolds compared to those from POC. The 20%AgMBG/POC additionally showed higher degradation rate in Tris(hydroxymethyl)-aminomethane-HCl (Tris-HCl) compared with pure POC and lost about 26% of its initial weight after soaking for 28 days. The AgMBG phase incorporation also significantly endowed the resulting composite scaffolds with efficient antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria while preserving their favorable biocompatibility with soft tissue cells (i.e., human dermal fibroblast cells). Taken together, our results suggest that the synergistic effect of both AgMBG and POC make these newly designed AgMBG/POC composite scaffold an attractive candidate for soft tissue engineering applications.
    Matched MeSH terms: Silver/chemistry*
  5. Fulltext Synthesis of silver nanoparticle-decorated hydroxyapatite nanocomposite with combined bioactivity and antibacterial properties
    Bee SL, Bustami Y, Ul-Hamid A, Lim K, Abdul Hamid ZA
    J Mater Sci Mater Med, 2021 Aug 23;32(9):106.
    PMID: 34426879 DOI: 10.1007/s10856-021-06590-y
    Combination of bioactive material such as hydroxyapatite (HAp) with antibacterial agents would have great potential to be used as bone implant materials to avert possible bacterial infection that can lead to implant-associated diseases. The present study aimed to develop an antibacterial silver nanoparticle-decorated hydroxyapatite (HAp/AgNPs) nanocomposite using chemical reduction and thermal calcination approaches. In this work, natural HAp that was extracted from chicken bone wastes is used as support matrix for the deposition of silver nanoparticles (AgNPs) to produce HAp/AgNPs nanocomposite. XRD, FESEM-EDX, HRTEM, and XPS analyses confirmed that spherical AgNPs were successfully synthesized and deposited on the surface of HAp particles, and the amount of AgNPs adhered on the HAp surface increased with increasing AgNO3 concentration used. The synthesized HAp/AgNPs nanocomposites demonstrated strong antibacterial activity against Staphylococcus aureus bacteria, where the antibacterial efficiency is relied on the amount and size of deposited AgNPs. In addition, the in vitro bioactivity examination in Hank's balanced salt solution showed that more apatite were grown on the surface of HAp/AgNPs nanocomposite when AgNO3 concentration used >1 wt.%. Such nanocomposite with enhanced bioactivity and antibacterial properties emerged as a promising biomaterial to be applied for dentistry and orthopedic implantology.
    Matched MeSH terms: Silver/chemistry*
  6. Fulltext Biogenic silver nanoparticles using Rhinacanthus nasutus leaf extract: synthesis, spectral analysis, and antimicrobial studies
    Pasupuleti VR, Prasad TN, Shiekh RA, Balam SK, Narasimhulu G, Reddy CS, et al.
    Int J Nanomedicine, 2013;8:3355-64.
    PMID: 24039419 DOI: 10.2147/IJN.S49000
    Nanotechnology is gaining momentum due to its ability to transform metals into nanoparticles. The synthesis, characterization, and applications of biologically synthesized nanomaterials have become an important branch of nanotechnology. Plant extracts are a cost-effective, ecologically friendly, and efficient alternative for the large-scale synthesis of nanoparticles. In this study, silver nanoparticles (AgNps) were synthesized using Rhinacanthus nasutus leaf extract. After exposing the silver ions to the leaf extract, the rapid reduction of silver ions led to the formation of AgNps in solution. The synthesis was confirmed by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The in vitro antimicrobial activity of the AgNps synthesized using R. nasutus leaf extract was investigated against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli, Aspergillus niger, and Aspergillus flavus using a disc diffusion method. The AgNps showed potential activity against all of the bacterial strains and fungal colonies, indicating that R. nasutus has the potential to be used in the development of value-added products in the biomedical and nanotechnology-based industries.
    Matched MeSH terms: Silver/chemistry*
  7. Brain-Eating Amoebae: Silver Nanoparticle Conjugation Enhanced Efficacy of Anti-Amoebic Drugs against Naegleria fowleri
    Rajendran K, Anwar A, Khan NA, Siddiqui R
    ACS Chem Neurosci, 2017 12 20;8(12):2626-2630.
    PMID: 29206032 DOI: 10.1021/acschemneuro.7b00430
    The overall aim of this study was to determine whether conjugation with silver nanoparticles enhances effects of available drugs against primary amoebic meningoencephalitis due to Naegleria fowleri. Amphotericin B, Nystatin, and Fluconazole were conjugated with silver nanoparticles, and synthesis was confirmed using UV-visible spectrophotometry. Atomic force microscopy determined their size in range of 20-100 nm. To determine amoebicidal effects, N. fowleri were incubated with drugs-conjugated silver nanoparticles, silver nanoparticles alone, and drugs alone. The findings revealed that silver nanoparticles conjugation significantly enhanced antiamoebic effects of Nystatin and Amphotericin B but not Fluconazole at micromolar concentrations, compared with the drugs alone. For the first time, our findings showed that silver nanoparticle conjugation enhances efficacy of antiamoebic drugs against N. fowleri. Given the rarity of the disease and challenges in developing new drugs, it is hoped that modifying existing drugs to enhance their antiamoebic effects is a useful avenue that holds promise in improving the treatment of brain-eating amoebae infection due to N. fowleri.
    Matched MeSH terms: Silver/chemistry
  8. Synthesis and characterization of nitrile functionalized silver(I)-N-heterocyclic carbene complexes: DNA binding, cleavage studies, antibacterial properties and mosquitocidal activity against the dengue vector, Aedes albopictus
    Asekunowo PO, Haque RA, Razali MR, Avicor SW, Wajidi MFF
    Eur J Med Chem, 2018 Apr 25;150:601-615.
    PMID: 29550733 DOI: 10.1016/j.ejmech.2018.03.029
    A series of four benzimidazolium based nitrile-functionalized mononuclear-Ag(I)-N-heterocyclic carbene and binuclear-Ag(I)-N-heterocyclic carbene (Ag(I)-NHC) hexafluorophosphate complexes (5b-8b) were synthesized by reacting the corresponding hexafluorophosphate salts (1b-4b) with Ag2O in acetonitrile, respectively. These compounds were characterized by 1H NMR, 13C NMR, IR, UV-visible spectroscopic techniques, elemental analyses and molar conductivity. Additionally, 8b was structurally characterized by single crystal X-ray diffraction technique. Preliminary in vitro antibacterial evaluation was conducted for all the compounds against two standard bacteria; gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacterial strains. Most of the Ag(I)-NHC complexes (5b-8b) showed moderate to good antibacterial activity with MIC values in the range of 12.5-100 μg/mL. Especially, compound 8b exhibited promising anti-Staphylococcus aureus activity with a low MIC value (12.5 μg/mL). However, all the hexafluorophosphate salts (1b-4b) were inactive against the bacteria strains. The preliminary interactive investigation revealed that the most active compound, 8b, could effectively intercalate into DNA to form 8b-DNA complex which shows a better binding ability for DNA (Kb = 3.627 × 106) than the complexes 5b-7b (2.177 × 106, 8.672 × 105 and 6.665 × 105, respectively). Nuclease activity of the complexes on plasmid DNA and Aedes albopictus genomic DNA was time-dependent, although minimal. The complexes were larvicidal to the mosquito, with 5b, 6b and 8b being highly active. Developmental progression from the larval to the adult stage was affected by the complexes, progressively being toxic to the insect's development with increasing concentration. These indicate the potential use of these complexes as control agents against bacteria and the dengue mosquito Ae. albopictus.
    Matched MeSH terms: Silver/chemistry
  9. Silver nanoparticles Clinacanthus Nutans leaves extract induced apoptosis towards oral squamous cell carcinoma cell lines
    Yakop F, Abd Ghafar SA, Yong YK, Saiful Yazan L, Mohamad Hanafiah R, Lim V, et al.
    Artif Cells Nanomed Biotechnol, 2018;46(sup2):131-139.
    PMID: 29561182 DOI: 10.1080/21691401.2018.1452750
    PURPOSE: The purpose of this study was to investigate apoptotic activity of silver nanoparticle Clinacanthus nutans (AgNps-CN) towards HSC-4 cell lines (oral squamous cell carcinoma cell lines).

    METHODS: Methods involved were MTT assay (cytotoxic activity), morphological cells analysis, flow cytometry and cell cycle analysis and western blot.

    RESULTS: MTT assay revealed IC50 concentration was 1.61 µg/mL, 3T3-L1 cell lines were used to determine whether AgNps-CN is cytotoxic to normal cells. At the highest concentration (3 µg/mL), no cytotoxic activity has been observed. Flow cytometry assay revealed AgNps-CN caused apoptosis effects towards HSC-4 cell lines with significant changes were observed at G1 phase when compared with untreated cells. Morphological cells analysis revealed that most of the cells exhibit apoptosis characteristics rather than necrosis. Protein study revealed that ratio of Bax/Bcl-2 increased mainly due to down-regulation of Bcl-2 expression.

    CONCLUSION: AgNps-CN have shown potential in inhibiting HSC-4 cell lines. IC50 was low compared to few studies involving biosynthesized of silver nanoparticles. Apoptosis effects were shown towards HSC-4 cell lines by the increased in Bax/Bcl-2 protein ratio. Further study such as PCR or in vivo studies are required.

    Matched MeSH terms: Silver/chemistry
  10. Repositioning of Guanabenz in Conjugation with Gold and Silver Nanoparticles against Pathogenic Amoebae Acanthamoeba castellanii and Naegleria fowleri
    Anwar A, Mungroo MR, Anwar A, Sullivan WJ, Khan NA, Siddiqui R
    ACS Infect Dis, 2019 Dec 13;5(12):2039-2046.
    PMID: 31612700 DOI: 10.1021/acsinfecdis.9b00263
    Brain-eating amoebae cause devastating infections in the central nervous system of humans, resulting in a mortality rate of 95%. There are limited effective therapeutic options available clinically for treating granulomatous amoebic encephalitis and primary amoebic meningoencephalitis caused by Acanthamoeba castellanii (A. castellanii) and Naegleria fowleri (N. fowleri), respectively. Here, we report for the first time that guanabenz conjugated to gold and silver nanoparticles has significant antiamoebic activity against both A. castellanii and N. fowleri. Gold and silver conjugated guanabenz nanoparticles were synthesized by the one-phase reduction method and were characterized by ultraviolet-visible spectrophotometry and atomic force microscopy. Both metals were facilely stabilized by the coating of guanabenz, which was examined by surface plasmon resonance determination. The average size of gold nanoconjugated guanabenz was found to be 60 nm, whereas silver nanoparticles were produced in a larger size distribution with the average diameter of around 100 nm. Guanabenz and its noble metal nanoconjugates exhibited potent antiamoebic effects in the range of 2.5 to 100 μM against both amoebae. Nanoparticle conjugation enhanced the antiamoebic effects of guanabenz, as more potent activity was observed at a lower effective concentration (2.5 and 5 μM) compared to the drug alone. Moreover, encystation and excystation assays revealed that guanabenz inhibits the interconversion between the trophozoite and cyst forms of A. castellanii. Cysticdal effects against N. fowleri were also observed. Notably, pretreatment of A. castellanii with guanabenz and its nanoconjugates exhibited a significant reduction in the host cell cytopathogenicity from 65% to 38% and 2% in case of gold and silver nanoconjugates, respectively. Moreover, the cytotoxic evaluation of guanabenz and its nanoconjugates revealed negligible cytotoxicity against human cells. Guanabenz is already approved for hypertension and crosses the blood-brain barrier; the results of our current study suggest that guanabenz and its conjugated gold and silver nanoparticles can be repurposed as a potential drug for treating brain-eating amoebic infections.
    Matched MeSH terms: Silver/chemistry*
  11. Fulltext Aluminosilicate Nanocomposites from Incinerated Chinese Holy Joss Fly Ash: A Potential Nanocarrier for Drug Cargos
    Ramanathan S, Gopinath SCB, Md Arshad MK, Poopalan P, Anbu P, Lakshmipriya T
    Sci Rep, 2020 Feb 25;10(1):3351.
    PMID: 32099019 DOI: 10.1038/s41598-020-60208-x
    An incredible amount of joss fly ash is produced from the burning of Chinese holy joss paper; thus, an excellent method of recycling joss fly ash waste to extract aluminosilicate nanocomposites is explored. The present research aims to introduce a novel method to recycle joss fly ash through a simple and straightforward experimental procedure involving acidic and alkaline treatments. The synthesized aluminosilicate nanocomposite was characterized to justify its structural and physiochemical characteristics. A morphological analysis was performed with field-emission transmission electron microscopy, and scanning electron microscopy revealed the size of the aluminosilicate nanocomposite to be ~25 nm, while also confirming a uniformly spherical-shaped nanostructure. The elemental composition was measured by energy dispersive spectroscopy and revealed the Si to Al ratio to be 13.24 to 7.96, showing the high purity of the extracted nanocomposite. The roughness and particle distribution were analyzed using atomic force microscopy and a zeta analysis. X-ray diffraction patterns showed a synthesis of faceted and cubic aluminosilicate crystals in the nanocomposites. The presence of silica and aluminum was further proven by X-ray photoelectron spectroscopy, and the functional groups were recognized through Fourier transform infrared spectroscopy. The thermal capacity of the nanocomposite was examined by a thermogravimetric analysis. In addition, the research suggested the promising application of aluminosilicate nanocomposites as drug carriers. The above was justified by an enzyme-linked apta-sorbent assay, which claimed that the limit of the aptasensing aluminosilicate-conjugated ampicillin was two-fold higher than that in the absence of the nanocomposite. The drug delivery property was further justified through an antibacterial analysis against Escherichia coli (gram-negative) and Bacillus subtilis (gram-positive).
    Matched MeSH terms: Silver/chemistry
  12. Fulltext Green synthesis of silver nanoparticles through reduction with Solanum xanthocarpum L. berry extract: characterization, antimicrobial and urease inhibitory activities against Helicobacter pylori
    Amin M, Anwar F, Janjua MRSA, Iqbal MA, Rashid U
    Int J Mol Sci, 2012;13(8):9923-9941.
    PMID: 22949839 DOI: 10.3390/ijms13089923
    A green synthesis route for the production of silver nanoparticles using methanol extract from Solanum xanthocarpum berry (SXE) is reported in the present investigation. Silver nanoparticles (AgNps), having a surface plasmon resonance (SPR) band centered at 406 nm, were synthesized by reacting SXE (as capping as well as reducing agent) with AgNO(3) during a 25 min process at 45 °C. The synthesized AgNps were characterized using UV-Visible spectrophotometry, powdered X-ray diffraction, and transmission electron microscopy (TEM). The results showed that the time of reaction, temperature and volume ratio of SXE to AgNO(3) could accelerate the reduction rate of Ag(+) and affect the AgNps size and shape. The nanoparticles were found to be about 10 nm in size, mono-dispersed in nature, and spherical in shape. In vitro anti-Helicobacter pylori activity of synthesized AgNps was tested against 34 clinical isolates and two reference strains of Helicobacter pylori by the agar dilution method and compared with AgNO(3) and four standard drugs, namely amoxicillin (AMX), clarithromycin (CLA), metronidazole (MNZ) and tetracycline (TET), being used in anti-H. pylori therapy. Typical AgNps sample (S1) effectively inhibited the growth of H. pylori, indicating a stronger anti-H. pylori activity than that of AgNO(3) or MNZ, being almost equally potent to TET and less potent than AMX and CLA. AgNps under study were found to be equally efficient against the antibiotic-resistant and antibiotic-susceptible strains of H. pylori. Besides, in the H. pylori urease inhibitory assay, S1 also exhibited a significant inhibition. Lineweaver-Burk plots revealed that the mechanism of inhibition was noncompetitive.
    Matched MeSH terms: Silver/chemistry*
  13. Fulltext Eco-friendly synthesis of silver nanoparticles and its larvicidal property against fourth instar larvae of Aedes aegypti
    Ali ZA, Roslan MA, Yahya R, Wan Sulaiman WY, Puteh R
    IET Nanobiotechnol, 2017 Mar;11(2):152-156.
    PMID: 28476997 DOI: 10.1049/iet-nbt.2015.0123
    In this study, larvicidal activity of silver nanoparticles (AgNPs) synthesised using apple extract against fourth instar larvae of Aedes aegypti was determined. As a result, the AgNPs showed moderate larvicidal effects against Ae. aegypti larvae (LC50 = 15.76 ppm and LC90 = 27.7 ppm). In addition, comparison of larvicidal activity performance of AgNPs at high concentration prepared using two different methods showed that Ae. aegypti larvae was fully eliminated within the duration of 2.5 h. From X-ray diffraction, the AgNP crystallites were found to exhibit face centred cubic structure. The average size of these AgNPs as estimated by particle size distribution was in the range of 50-120 nm. The absorption maxima of the synthesised Ag showed characteristic Ag surface plasmon resonance peak. This green synthesis provides an economic, eco-friendly and clean synthesis route to Ag.
    Matched MeSH terms: Silver/chemistry
  14. Fulltext Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity
    Shameli K, Ahmad MB, Yunus WM, Rustaiyan A, Ibrahim NA, Zargar M, et al.
    Int J Nanomedicine, 2010 Oct 22;5:875-87.
    PMID: 21116328 DOI: 10.2147/IJN.S13632
    In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO(3) were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller-Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles.
    Matched MeSH terms: Silver/chemistry
  15. Silver(I) complexes of mono- and bidentate N-heterocyclic carbene ligands: synthesis, crystal structures, and in vitro antibacterial and anticancer studies
    Haque RA, Choo SY, Budagumpi S, Iqbal MA, Al-Ashraf Abdullah A
    Eur J Med Chem, 2015 Jan 27;90:82-92.
    PMID: 25461313 DOI: 10.1016/j.ejmech.2014.11.005
    A series of benzimidazole-based N-heterocyclic carbene (NHC) proligands {1-benzyl-3-(2-methylbenzyl)-benzimidazolium bromide/hexafluorophosphate (1/4), 1,3-bis(2-methylbenzyl)-benzimidazolium bromide/hexafluorophosphate (2/5) and 1,3-bis(3-(2-methylbenzyl)-benzimidazolium-1-ylmethylbenzene dibromide/dihexafluorophosphate (3/6)} has been synthesized by the successive N-alkylation method. Ag complexes {1-benzyl-3-(2-methylbenzyl)-benzimidazol-2-ylidenesilver(I) hexafluorophosphate (7), 1,3-bis(2-methylbenzyl)-benzimidazol-2-ylidenesilver(I) hexafluorophosphate (8) and 1,3-bis(3-(2-methylbenzyl)-benzimidazol-2-ylidene)-1-ylmethylbenzene disilver(I) dihexafluorophosphate (9)} of NHC ligands have been synthesized by the treatment of benzimidazolium salts with Ag2O at mild reaction conditions. Both, NHC proligands and Ag-NHC complexes have been characterized by (1)H and (13)C{(1)H} NMR and FTIR spectroscopy and elemental analysis technique. Additionally, the structure of the NHC proligand 5 and the mononuclear Ag complexes 7 and 8 has been elucidated by the single crystal X-ray diffraction analysis. Both the complexes exhibit the same general structural motif with linear coordination geometry around the Ag centre having two NHC ligands. Preliminary in vitro antibacterial potentials of reported compounds against a Gram negative (Escherichia coli) and a Gram positive (Bacillus subtilis) bacteria evidenced the higher activity of mononuclear silver(I) complexes. The anticancer studies against the human derived colorectal cancer (HCT 116) and colorectal adenocarcinoma (HT29) cell lines using the MTT assay method, revealed the higher activity of Ag-NHC complexes. The benzimidazolium salts 4-6 and Ag-NHC complexes 7-9 displayed the following IC50 values against the HCT 116 and HT29 cell lines, respectively, 31.8 ± 1.9, 15.2 ± 1.5, 4.8 ± 0.6, 10.5 ± 1.0, 18.7 ± 1.6, 1.20 ± 0.3 and 245.0 ± 4.6, 8.7 ± 0.8, 146.1 ± 3.1, 7.6 ± 0.7, 5.5 ± 0.8, 103.0 ± 2.3 μM.
    Matched MeSH terms: Silver/chemistry
  16. Fulltext Anti-biofilm agents: recent breakthrough against multi-drug resistant Staphylococcus aureus
    Chung PY, Toh YS
    Pathog Dis, 2014 Apr;70(3):231-9.
    PMID: 24453168 DOI: 10.1111/2049-632X.12141
    Staphylococcus aureus is a Gram-positive pathogen that causes potentially life-threatening nosocomial- and community-acquired infections, such as osteomyelitis and endocarditis. Staphylococcus aureus has the ability to form multicellular, surface-adherent communities called biofilms, which enables it to survive in various sources of stress, including antibiotics, nutrient limitations, heat shock, and immune responses. Biofilm-forming capacity is now recognized as an important virulence determinant in the development of staphylococcal device-related infections. In light of the projected increase in the numbers of elderly patients who will require semi-permanent indwelling medical devices such as artificial knees and hips, we can anticipate an expanded need for new agents and treatment options to manage biofilm-associated infections in an expanding at-risk population. With better understanding of staphylococcal biofilm formation and growth, novel strategies that target biofilm-associated infections caused by S. aureus have recently been described and seem promising as future anti-biofilm therapies.
    Matched MeSH terms: Silver/chemistry
  17. Cytotoxicity and immunological responses following oral vaccination of nanoencapsulated avian influenza virus H5 DNA vaccine with green synthesis silver nanoparticles
    Jazayeri SD, Ideris A, Zakaria Z, Shameli K, Moeini H, Omar AR
    J Control Release, 2012 Jul 10;161(1):116-23.
    PMID: 22549012 DOI: 10.1016/j.jconrel.2012.04.015
    DNA formulations provide the basis for safe and cost effective vaccine. Low efficiency is often observed in the delivery of DNA vaccines. In order to assess a new strategy for oral DNA vaccine formulation and delivery, plasmid encoding hemagglutinin (HA) gene of avian influenza virus, A/Ck/Malaysia/5858/04 (H5N1) (pcDNA3.1/H5) was formulated using green synthesis of sliver nanoparticles (AgNP) with polyethylene glycol (PEG). AgNP were successfully synthesized uniformly dispersed with size in the range of 4 to 18 nm with an average size of 11 nm. Cytotoxicity of the prepared AgNP was investigated in vitro and in vivo using MCF-7 cells and cytokine expression, respectively. At the concentration of -5 log₁₀AgNP, no cytotoxic effects were detected in MCF-7 cells with 9.5% cell death compared to the control. One-day-old specific pathogen-free (SPF) chicks immunized once by oral gavage with 10 μl of pcDNA3.1/H5 (200 ng/ml) nanoencapsulated with 40 μl AgNP (3.7×10⁻² μg of Ag) showed no clinical manifestations. PCR successfully detect the AgNP/H5 plasmid from the duodenum of the inoculated chicken as early as 1h post-immunization. Immunization of chickens with AgNP/H5 enhanced both pro inflammatory and Th1-like expressions, although no significant differences were recorded in the chickens inoculated with AgNP, AgNP/pcDNA3.1 and the control. In addition, serum samples collected from immunized chickens with AgNP/H5 showed rapidly increasing antibody against H5 on day 14 after immunization. The highest average antibody titres were detected on day 35 post-immunization at 51.2±7.5. AgNP/H5 also elicited both CD4+ and CD8+ T cells in the immunized chickens as early as day 14 after immunization, at 7.5±2.0 and 20±1.9 percentage, respectively. Hence, single oral administrations of AgNP/H5 led to induce both the antibody and cell-mediated immune responses as well as enhanced cytokine production.
    Matched MeSH terms: Silver/chemistry
  18. Fulltext Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity
    Shameli K, Bin Ahmad M, Zargar M, Yunus WM, Ibrahim NA, Shabanzadeh P, et al.
    Int J Nanomedicine, 2011;6:271-84.
    PMID: 21499424 DOI: 10.2147/IJN.S16043
    Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24-1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28-9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles.
    Matched MeSH terms: Silver/chemistry*
  19. Fulltext Gene expression profiles in primary duodenal chick cells following transfection with avian influenza virus H5 DNA plasmid encapsulated in silver nanoparticles
    Jazayeri SD, Ideris A, Shameli K, Moeini H, Omar AR
    Int J Nanomedicine, 2013;8:781-90.
    PMID: 23459681 DOI: 10.2147/IJN.S39074
    In order to develop a systemically administered safe and effective nonviral gene delivery system against avian influenza virus (AIV) that induced cytokine expression, the hemagglutinin (H5) gene of AIV, A/Ck/Malaysia/5858/04 (H5N1) and green fluorescent protein were cloned into a coexpression vector pIRES (pIREGFP-H5) and formulated using green synthesis of silver nanoparticles (AgNPs) with poly(ethylene glycol) and transfected into primary duodenal cells taken from 18-day-old specific-pathogen-free chick embryos. The AgNPs were prepared using moderated temperature and characterized for particle size, surface charge, ultraviolet-visible spectra, DNA loading, and stability. AgNPs and AgNP-pIREGFP-H5 were prepared in the size range of 13.9 nm and 25 nm with a positive charge of +78 ± 0.6 mV and +40 ± 6.2 mV, respectively. AgNPs with a positive surface charge could encapsulate pIREGFP-H5 efficiently. The ultraviolet-visible spectra for AgNP-pIREGFP-H5 treated with DNase I showed that the AgNPs were able to encapsulate pIREGFP-H5 efficiently. Polymerase chain reaction showed that AgNP-pIREGFP-H5 entered into primary duodenal cells rapidly, as early as one hour after transfection. Green fluorescent protein expression was observed after 36 hours, peaked at 48 hours, and remained stable for up to 60 hours. In addition, green fluorescent protein expression generally increased with increasing DNA concentration and time. Cells were transfected using Lipocurax in vitro transfection reagent as a positive control. A multiplex quantitative mRNA gene expression assay in the transfected primary duodenal cells via the transfection reagent and AgNPs with pIREGFP-H5 revealed expression of interleukin (IL)-18, IL-15, and IL-12β.
    Matched MeSH terms: Silver/chemistry*
  20. Fulltext Robust Synthesis of Ciprofloxacin-Capped Metallic Nanoparticles and Their Urease Inhibitory Assay
    Nisar M, Khan SA, Qayum M, Khan A, Farooq U, Jaafar HZ, et al.
    Molecules, 2016 Mar 25;21(4):411.
    PMID: 27023506 DOI: 10.3390/molecules21040411
    The fluoroquinolone antibacterial drug ciprofloxacin (cip) has been used to cap metallic (silver and gold) nanoparticles by a robust one pot synthetic method under optimized conditions, using NaBH₄ as a mild reducing agent. Metallic nanoparticles (MNPs) showed constancy against variations in pH, table salt (NaCl) solution, and heat. Capping with metal ions (Ag/Au-cip) has significant implications for the solubility, pharmacokinetics and bioavailability of fluoroquinolone molecules. The metallic nanoparticles were characterized by several techniques such as ultraviolet visible spectroscopy (UV), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) methods. The nanoparticles synthesized using silver and gold were subjected to energy dispersive X-ray tests in order to show their metallic composition. The NH moiety of the piperazine group capped the Ag/Au surfaces, as revealed by spectroscopic studies. The synthesized nanoparticles were also assessed for urease inhibition potential. Fascinatingly, both Ag-cip and Au-cip NPs exhibited significant urease enzyme inhibitory potential, with IC50 = 1.181 ± 0.02 µg/mL and 52.55 ± 2.3 µg/mL, compared to ciprofloxacin (IC50 = 82.95 ± 1.62 µg/mL). MNPs also exhibited significant antibacterial activity against selected bacterial strains.
    Matched MeSH terms: Silver/chemistry
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