Toxicity of internalized laser generated pure silver nanoparticles to the isolated rat hippocampus cells

Silver nanoparticles (AgNPs) are the most commonly used nanoparticles (NPs) in medicine, industry and cosmetics. They are generally considered as biocompatible. However, contradictory reports on their biosafety render them difficult to accept as ‘safe’. In this study, we evaluated the neurotoxicity of direct AgNP treatment in rat hippocampal slices. We produced pure uncoated AgNPs by a pulsed laser ablation method. NP characterization was performed by Ultraviolet (UV) visible spectrophotometer, scanning electron microscope, transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy. Rat hippocampal slices were treated with AgNPs for an hour. AgNP exposure of hippocampal tissue resulted in a significant decrease in cell survival in a dose-dependent manner. Our TEM results showed that AgNPs were distributed in the extracellular matrix and were taken into the cytoplasm of the neurons. Moreover, we found that only larger AgNPs were taken into the neurons via phagocytosis. This study showed that the pure AgNPs produced by laser ablation are toxic to the neural tissue. We also found that neurons internalized only the large NPs by phagocytosis which seems to be the major mechanism in AgNP neurotoxicity.

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Synthesis, Characterization, and Optimization of Green Silver Nanoparticles Using Neopestalotiopsis clavispora and Evaluation of Its Antibacterial, Antibiofilm, and Genotoxic Effects

The EuroBiotech Journal ◽

10.2478/ebtj-2021-0020 ◽

2021 ◽

Vol 5 (3) ◽

pp. 109-122

Author(s):

Tuğba Kahraman ◽

Safiye Elif Korcan ◽

Recep Liman ◽

İbrahim Hakkı Ciğerci ◽

Yaser Acikbas ◽

...

Keyword(s):

Silver Nanoparticles ◽

Nuclear Ribosomal Dna ◽

Diffusion Method ◽

Dependent Manner ◽

Transmission Electron ◽

Infrared Spectrophotometer ◽

Average Size ◽

Novel Applications ◽

Dose Dependent

Abstract Silver nanoparticles (AgNPs) have been used in a variety of biomedical applications in the last two decades, including antimicrobial, anti-inflammatory, and anticancer treatments. The present study highlights the extracellular synthesis of silver nanoparticles AgNPs using Neopestalotiopsis clavispora MH244410.1 and its antibacterial, antibiofilm, and genotoxic properties. Locally isolated N. clavispora MH244410.1 was identified by Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA. Optimization of synthesized AgNPs was performed by using various parameters (pH (2, 4, 7, 9 and 12), temperature (25, 35 and 45 °C), and substrate concentration (0.05, 0.1, 0.15, 0.2 and 0.25 mM)). After 72 hours of incubation in dark conditions, the best condition for the biosynthesis of AgNPs was determined as 0.25 mM metal concentration at pH 12 and 35 °C. Fungal synthesized AgNPs were characterized via spectroscopic and microscopic techniques such as Fouirer Transform Infrared Spectrophotometer (FTIR), UV-Visible Spectroscopy, and Transmission Electron Microscopy (TEM). The average size of the AgNPs was determined less than 60 nm using the TEM and Zetasizer measurement system (measured in purity water suspension). The characteristic peak of AgNPs was observed at ~414 nm from UV-Vis results. Antibacterial and genotoxic activity of synthesized AgNPs (0.1, 1, and 10 ppm) were also determined by using the agar well diffusion method and in vivo Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster. AgNPs exhibited potential antimicrobial activity against all the tested bacteria (Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) except Escherichia coli in a dose-dependent manner. AgNPs did not induce genotoxicity in the Drosophila SMART assay. 79.33, 65.47, and 41.95% inhibition of biofilms formed by P. aeruginosa were observed at 10, 1, and 0.1 ppm of AgNPs, respectively. The overall results indicate that N. clavispora MH244410.1 is a good candidate for novel applications in biomedical research.

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Preparation of Colloidal Silver Nanoparticles by Laser Ablation; Evaluation and Study on its Developed Applications

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.488-489.1409 ◽

2012 ◽

Vol 488-489 ◽

pp. 1409-1413

Author(s):

Adeleh Granmayeh Rad ◽

Hamed Abbasi

Keyword(s):

Silver Nanoparticles ◽

Laser Ablation ◽

Colloidal Silver ◽

Laser Ablation Method ◽

Colloidal Silver Nanoparticles ◽

Novel Approach ◽

Transmission Electron ◽

Good Potential ◽

Average Size ◽

20 Nm

In this work we report the preparation of colloidal silver nanoparticles. In order to prepare the silver nanoparticles laser ablation method has been used.A silver coin as a target (purity 99.9 %) was ablated by a Q-Switched Nd:YAG laser with a fluence of about 91 mJ/cm2 at a repetition rate of 10 Hz at room temperature. In order to evaluate these particles transmission electron microscopy (TEM) and spectrophotometry (from UV to NIR) have been used. The average size of prepared nanoparticles is ~ 20 nm. The importance of morphology of nanoparticles has been investigated. Developed applications of silver nanoparticles have been studied,silver nanoparticles are considered as biocompatible and low in toxicity and have good potential for biological applications. Lately silver nanoparticles have found a novel approach in different fields of medicine, biology and industry.

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MORPHOLOGIES OF SILVER NANOPARTICLES (Ag NPs) SYNTHESIZED BY HYDROTHERMAL AND LASER ABLATION TECHNIQUES

Surface Review and Letters ◽

10.1142/s0218625x20500158 ◽

2020 ◽

Vol 27 (12) ◽

pp. 2050015

Author(s):

REHANA SHAHID ◽

SIDRA KHALID ◽

SHAMAILA SHAHZADI

Keyword(s):

Electron Microscopy ◽

Silver Nanoparticles ◽

Laser Ablation ◽

Hydrothermal Process ◽

Suitable Method ◽

Ag Nps ◽

Uniform Size ◽

X Ray ◽

Laser Ablation Method ◽

Transmission Electron

Silver nanoparticles (Ag NPs) are prepared using two different techniques namely hydrothermal and laser ablation methods. The purpose of this study is to find a more suitable method to prepare Ag NPs through comparison that can give stable and size-controlled silver nanoparticles. Techniques used for observations are X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Comparison of results exhibited that hydrothermal process is a more suitable method to prepare silver nanoparticles with smaller uniform size and better yield as compared to laser ablation method. Also, at low temperature, NPs obtained using hydrothermal process provide better control on morphology, high purity and narrow size distribution.

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MicroRNA-106a Inhibits Autophagy Process and Antimicrobial Responses by Targeting ULK1, ATG7, and ATG16L1 During Mycobacterial Infection

Frontiers in Immunology ◽

10.3389/fimmu.2020.610021 ◽

2021 ◽

Vol 11 ◽

Author(s):

Kunmei Liu ◽

Dantong Hong ◽

Fan Zhang ◽

Xin Li ◽

Meng He ◽

...

Keyword(s):

Immune Response ◽

Electron Microscope ◽

Mycobacterial Infection ◽

Inhibitory Effect ◽

Innate Immune ◽

Negative Regulator ◽

Dependent Manner ◽

Transmission Electron ◽

Dose Dependent

Autophagy is a key element of innate immune response against invading pathogens including Mycobacterium tuberculosis (M. tuberculosis). The emerging roles of microRNAs in regulating host antimicrobial responses against M. tuberculosis have gained widespread attention. However, the process by which miRNAs specifically influence antibacterial autophagy during mycobacterial infection is largely uncharacterized. In this study, we demonstrate a novel role of miR-106a in regulating macrophage autophagy against M. tuberculosis. H37Ra infection leads to downregulation of miR-106a in a time- and dose-dependent manner and concomitant upregulation of its three targets (ULK1, ATG7, and ATG16L1) in THP-1 macrophages. MiR-106a could inhibit autophagy activation and antimicrobial responses to M. tuberculosis by targeting ULK1, ATG7, and ATG16L1. Overexpression of miR-106a dramatically inhibited H37Ra-induced activation of autophagy in human THP-1 macrophages, whereas inhibitors of miR-106a remarkably promoted H37Ra-induced autophagy. The inhibitory effect of miR-106a on autophagy process during mycobacterial infection was also confirmed by Transmission Electron Microscope (TEM) observation. More importantly, forced expression of miR-106a increased mycobacterial survival, while transfection with miR-106a inhibitors attenuated the survival of intracellular mycobacteria. Taken together, these data demonstrated that miR-106a functioned as a negative regulator in autophagy and antimicrobial effects by targeting ULK1, ATG7, and ATG16L1 during M. tuberculosis infection, which may provide a potential target for developing diagnostic reagents or antibacterials against tuberculosis.

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Comparative Biocompatibilities of Various Sizes of AgCIT and AgPVP with their Protein Coronas Nanoparticles

Journal of the chemical society of pakistan ◽

10.52568/000594 ◽

2021 ◽

Vol 43 (5) ◽

pp. 513-513

Author(s):

Abdul Hameed Abdul Hameed ◽

Komal Saba Komal Saba ◽

Raheela Taj Raheela Taj ◽

Andaleeb Azam Andaleeb Azam ◽

Rohullah and Amna Paracha Rohullah and Amna Paracha

Keyword(s):

Silver Nanoparticles ◽

Electron Microscope ◽

Biomedical Applications ◽

Cytotoxic Effect ◽

Human Hepatoma ◽

Hepg2 Cell Line ◽

Supported Nanoparticles ◽

Transmission Electron ◽

Uv Visible ◽

20 Nm

Biocompatibilities of nanoparticles are crucial for biomedical applications. Diverse silver nanoparticles (5 nm, 10 nm, 20 nm, 40 nm and 80 nm) caped with citrate and polyvinylpyrrolidone (PVP) were synthesized and primed their protein coronas. Nanoparticles were characterized with UV-visible spectroscope, Dynamic light scattering (DLS) and Transmission Electron Microscope (TEM). Comparative biocompatibilities were verified and recorded using MTS techniques. Human hepatoma carcinoma HepG2) cell line was used for measuring cytotoxic effect by MTS assays. Deleterious and comparative behaviors of citrate and PVP supported nanoparticles with varied dimensions were investigated and concluded; that citrate caped nanoparticles are comparatively less toxic and independent of size than PVP supported nanoparticles, having increased cytotoxicity with increasing size. The cytotoxic effect of citrate caped and its protein coronas nanoparticles was insignificant, while the boosted concentration of PVP supported nanoparticles enhanced the toxic effect, which endorsed enlarged size and amount of PVP supported nanoparticles. As medicinal precursors, the overwhelming use of PVP nanoparticles should be avoided, and a unique protocol must be designed if its use is crucial and unavoidable.

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Biofabricated Fatty Acids-Capped Silver Nanoparticles as Potential Antibacterial, Antifungal, Antibiofilm and Anticancer Agents

Pharmaceuticals ◽

10.3390/ph14020139 ◽

2021 ◽

Vol 14 (2) ◽

pp. 139

Author(s):

Mohammad Azam Ansari ◽

Sarah Mousa Maadi Asiri ◽

Mohammad A. Alzohairy ◽

Mohammad N. Alomary ◽

Ahmad Almatroudi ◽

...

Keyword(s):

Fatty Acids ◽

Silver Nanoparticles ◽

Anticancer Agents ◽

Sem Analysis ◽

Dependent Manner ◽

Anticancer Activities ◽

Anticancer Efficacy ◽

Hct 116 ◽

Hct 116 Cells ◽

Dose Dependent

The current study demonstrates the synthesis of fatty acids (FAs) capped silver nanoparticles (AgNPs) using aqueous poly-herbal drug Liv52 extract (PLE) as a reducing, dispersing and stabilizing agent. The NPs were characterized by various techniques and used to investigate their potent antibacterial, antibiofilm, antifungal and anticancer activities. GC-MS analysis of PLE shows a total of 37 peaks for a variety of bio-actives compounds. Amongst them, n-hexadecanoic acid (21.95%), linoleic acid (20.45%), oleic acid (18.01%) and stearic acid (13.99%) were found predominately and most likely acted as reducing, stabilizing and encapsulation FAs in LIV-AgNPs formation. FTIR analysis of LIV-AgNPs shows some other functional bio-actives like proteins, sugars and alkenes in the soft PLE corona. The zone of inhibition was 10.0 ± 2.2–18.5 ± 1.0 mm, 10.5 ± 2.5–22.5 ± 1.5 mm and 13.7 ± 1.0–16.5 ± 1.2 against P. aeruginosa, S. aureus and C. albicans, respectively. LIV-AgNPs inhibit biofilm formation in a dose-dependent manner i.e., 54.4 ± 3.1%—10.12 ± 2.3% (S. aureus), 72.7 ± 2.2%–23.3 ± 5.2% (P. aeruginosa) and 85.4 ± 3.3%–25.6 ± 2.2% (C. albicans), and SEM analysis of treated planktonic cells and their biofilm biomass validated the fitness of LIV-AgNPs in future nanoantibiotics. In addition, as prepared FAs rich PLE capped AgNPs have also exhibited significant (p < 0.05 *) antiproliferative activity against cultured HCT-116 cells. Overall, this is a very first demonstration on employment of FAs rich PLE for the synthesis of highly dispersible, stable and uniform sized AgNPs and their antibacterial, antifungal, antibiofilm and anticancer efficacy.

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Optical and Photoacoustic Properties of Laser-Ablated Silver Nanoparticles in a Carbon Dots Solution

Molecules ◽

10.3390/molecules25245798 ◽

2020 ◽

Vol 25 (24) ◽

pp. 5798

Author(s):

Amir Reza Sadrolhosseini ◽

Ganesan Krishnan ◽

Suhaidi Shafie ◽

Suraya Abdul Rashid ◽

Sulaiman Wadi Harun

Keyword(s):

Silver Nanoparticles ◽

Carbon Dots ◽

Thermal Effusivity ◽

Nonlinear Susceptibility ◽

Time Range ◽

Raman Signal ◽

Optical Parameters ◽

Visible Spectroscopy ◽

Transmission Electron ◽

Uv Visible

This study used the carbon dots solution for the laser ablation technique to fabricate silver nanoparticles. The ablation time range was from 5 min to 20 min. Analytical methods, including Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, transmission electron microscopy, and Raman spectroscopy were used to categorize the prepared samples. The UV-visible and z-scan techniques provided optical parameters such as linear and nonlinear refractive indices in the range of 1.56759 to 1.81288 and 7.3769 × 10−10 cm2 W−1 to 9.5269 × 10−10 cm2 W−1 and the nonlinear susceptibility was measured in the range of 5.46 × 10−8 to 6.97 × 10−8 esu. The thermal effusivity of prepared samples, which were measured using the photoacoustic technique, were in the range of 0.0941 W s1/2 cm−2 K−1 to 0.8491 W s1/2 cm−2 K−1. The interaction of the prepared sample with fluoride was investigated using a Raman spectrometer. Consequently, the intensity of the Raman signal decreased with the increasing concentration of fluoride, and the detection limit is about 0.1 ppm.

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Effects of Propentofylline on Hypoxia—Hypoglycemia-Induced Calcium Accumulation in Gerbil Hippocampal Slices

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1992.41 ◽

1992 ◽

Vol 12 (2) ◽

pp. 301-305 ◽

Cited By ~ 12

Author(s):

Fumito Kadoya ◽

Akira Mitani ◽

Tatsuru Arai ◽

Kiyoshi Kataoka

Keyword(s):

Cerebral Ischemia ◽

Intracellular Calcium ◽

Neuronal Damage ◽

Hippocampal Slices ◽

Dependent Manner ◽

Protective Effects ◽

Calcium Accumulation ◽

Xanthine Derivative ◽

Acute Increase ◽

Dose Dependent

The xanthine derivative propentofylline (HWA 285) has been reported to show protective effects against neuronal damage induced by cerebral ischemia. In the present study, microfluorometry was used to investigate the effect of propentofylline on the hypoxia–hypoglycemia-induced intracellular calcium accumulation in gerbil hippocampal slices. When slices were superfused with hypoxic–hypoglycemic medium that did not contain propentofylline, an acute increase in calcium accumulation was detected 75–200 s (mean latency of 123 s) after the beginning of hypoxia–hypoglycemia. When slices were superfused with hypoxic–hypoglycemic mediums that contained 10 μ M, 100 μ M, and 1 m M propentofylline, the latency of the acute increase in calcium accumulation was prolonged in all subregions of the hippocampus in a dose-dependent manner: mean latencies in field CA1 were 146, 168, and 197 s after hypoxia–hypoglycemia, respectively. This retardation in calcium accumulation may be involved in the mechanisms by which propentofylline diminishes ischemic injury.

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Preparation of Triangular Silver Nanoparticles Using Polyvinyl Pyrrolidone with Different Concentration

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.873.206 ◽

2013 ◽

Vol 873 ◽

pp. 206-210

Author(s):

Kai Li ◽

Rao Fu ◽

Qing Ran Gao ◽

Ai Wei Tang ◽

Ying Feng Wang

Keyword(s):

Electron Microscopy ◽

Aqueous Solution ◽

Silver Nanoparticles ◽

Driving Force ◽

Ostwald Ripening ◽

Polyvinyl Pyrrolidone ◽

Protective Agent ◽

Ag Nps ◽

Transmission Electron ◽

Uv Visible

This paper continues our previous work on preparation of triangular silver nanoparticles. The method proceeds with reaction of silver nitrate with hydrazine hydrate in the presence of polyvinyl pyrrolidone in aqueous solution. Effects of the concentration of PVP on the morphologies of Ag NPs were systematically investigated. The obtained Ag NPs were characterized by transmission electron microscopy and UV-visible spectrophotometer. The results showed that, triangular Ag NPs with edge lengths in the range of 50-200 nm were obtained using PVP as protective agent with lower concentration. As the concentration of PVP increased, spherical Ag NPs with their sizes about 6.2 nm were prepared and triangular Ag NPs were not obtained. The formation mechanism of triangular Ag NPs has been studied. Ostwald ripening is the driving force on the conversion of spherical Ag NPs to triangular Ag NPs in the presence of PVP.

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Presynaptic Modulation of Synaptic Transmission by Pregnenolone Sulfate as Studied by Optical Recordings

Journal of Neurophysiology ◽

10.1152/jn.00755.2004 ◽

2005 ◽

Vol 94 (6) ◽

pp. 4131-4144 ◽

Cited By ~ 35

Author(s):

Ling Chen ◽

Masahiro Sokabe

Keyword(s):

Synaptic Transmission ◽

Glutamate Release ◽

Hippocampal Slices ◽

Receptor Activation ◽

Optical Recording ◽

Perforant Path ◽

Dependent Manner ◽

Pregnenolone Sulfate ◽

Voltage Sensitive Dyes ◽

Dose Dependent

The effects of pregnenolone sulfate (PREGS), a putative neurosteroid, on the transmission of perforant path–granule cell synapses were investigated with an optical recording technique in rat hippocampal slices stained with voltage-sensitive dyes. Application of PREGS to the bath solution resulted in an acute augmentation of EPSP in a dose-dependent manner. The PREGS effect was dependent on the extracellular Ca2+ concentration ([Ca2+]o), but independent of NMDA receptor activation. PREGS caused a decrease in paired-pulse facilitation, which implies that PREGS positively modulates presynaptic neurotransmitter releases. Firmer support for this mechanism was that PREGS augmented the synaptically induced glial depolarization (SIGD) that reflects the activity of electrogenic glutamate transporters in glial cells during the uptake of released glutamate. The selective α7nAChR antagonist α-BGT or MLA prevented the SIGD increase by PREGS. Furthermore DMXB, a selective α7nAChR agonist, mimicked the PREGS effect on SIGD and antagonized the effect of PREGS. The presynaptic effect of PREGS was partially attenuated by the L-type Ca2+ channel (VGCC) blocker nifedipine. Based on these findings, we proposed a novel mechanism underlying the facilitated synaptic transmission by PREGS: this neurosteroid sensitizes presynaptic α7nAChR that is followed by an activation of L-type VGCC to increase the presynaptic glutamate release.

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