scholarly journals Variability and improvement of optical and antimicrobial performances for CQDs/mesoporous SiO2/Ag NPs composites via in situ synthesis

2021 ◽  
Vol 10 (1) ◽  
pp. 403-411
Author(s):  
Youliang Cheng ◽  
Mingjie Wang ◽  
Changqing Fang ◽  
Ying Wei ◽  
Jing Chen ◽  
...  
Keyword(s):  
Uv Light ◽  
Carbon Quantum Dots ◽  
Diffusion Method ◽  
Ag Nps ◽  
Uniform Size ◽  
High Antibacterial Activity ◽  
Fluorescent Materials ◽  
Potential Applications ◽  
Mesoporous Sio2

Abstract To change the optical properties and improve the antibacterial performances of carbon quantum dots (CQDs) and Ag NPs, mesoporous SiO2 spheres were combined with them to form the composites. In this paper, CQDs with a uniform size of about 3.74 nm were synthesized using glucose as carbon source. Then, CQDs/mesoporous SiO2/Ag NPs composites were obtained in situ under UV light irradiating by using mesoporous SiO2 and Ag NO3 as the carrier and silver resource, respectively. The diameter of CQDs/mesoporous SiO2/Ag NPs particles was in the range of 200–250 nm. With the increase in irradiating time, the red-shift in the UV-Vis spectrum for as-prepared CQDs/mesoporous SiO2/Ag NPs composites was found, and the adsorption peak was widened. In addition, the composites showed a high antibacterial activity against Staphylococcus aureus and Escherichia coli via disc diffusion method. These results indicated that inhibition circles for Ag NPs/mesoporous SiO2/CQDs and mesoporous SiO2/Ag NPs were similar in diameter. Furthermore, the two composites had a better bactericidal performance compared with other particles. Therefore, as-prepared CQDs/mesoporous SiO2/Ag NPs composites in this paper have great potential applications for fluorescent materials and antibacterial materials.

Antimicrobial Activity of O-Carboxymethyl Chitosan Nanofibers Containing Silver Nanoparticles Synthesized by Green Method

2016 ◽  
Vol 40 ◽  
pp. 136-145 ◽  
Author(s):  
Metwally Ezzat ◽  
Mohammed Ghanim ◽  
Hassan Nageh ◽  
Ahmed H. Hassanin ◽  
Ahmed Abdel-Moneim
Keyword(s):  
Antibacterial Activity ◽  
Wound Dressing ◽  
Pathogenic Bacteria ◽  
Reaction Times ◽  
Carboxymethyl Chitosan ◽  
Diffusion Method ◽  
Ag Nps ◽  
High Antibacterial Activity ◽  
Transmission Electron ◽  
Bacteria And Fungi

New green synthesis of Ag-nanoparticles (Ag-NPs) using O-Carboxymethyl Chitosan (O-CMCs) as stabilizing agent and ascorbic acid as reducing agent was achieved. The reaction was carried out in an autoclave at a pressure of 0.12 MPa and a temperature of 120°C at varying concentrations of solution precursors and different reaction times. The size, shape and structure of Ag-NPs were measured using transmission electron microscope (TEM), X-Ray Diffraction (XRD), FT-IR and UV spectrophotometers. The Ag-NPs stabilized in O-CMCs were blended with polyvinyl alcohol (PVA) polymer solution and then electrospun to produce wound dressing nanofibers with high antibacterial activity. The morphological study of O-CMCs/ PVA/Ag-NPs nanofiber membranes was characterized using SEM. Finally, the release behavior of Ag-NPs from these nanofibers was examined and the antibacterial activity was measured against some skin pathogenic bacteria and fungi using the agar diffusion method. The newly developed membranes show a unique antibacterial activity against the tested strains and were presented as promising active wound dressing materials in medical applications.

scholarly journals Photosynthesis of Silver Nanoparticle – Carbon Quantum Dots Nanocomposites

2019 ◽  
Vol 16 (2) ◽  
pp. 118-124
Author(s):  
Xuan-Dung Mai ◽  
Quang-Trung Le ◽  
Lan-Anh Nguyen Thi ◽  
Phuong Nguyen Thi ◽  
Phuong Le Thi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Silver Ions ◽  
Carbon Quantum Dots ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Ir And Raman Spectroscopies ◽  
Surface Enhanced Raman ◽  
Potential Applications ◽  
Enhanced Raman Scattering

Nanocomposites (NCs) of silver nanoparticles (Ag NPs) and carbon quantum dots (CQDs) have been received increasing attention for diverse applications including sensing, photocatalyst, surface enhanced Raman scattering detection and antibacterial. Herein, we report a unique photosynthesis of Ag NPs-CQD using CQDs as photo-reducing agent. Highly luminescent CQDs were prepared by a hydrothermal method using a mixture of citric acid (CA) and ethylenediamine (EDA) as starting precursors. X-ray diffraction pattern (XRD), transmission electron microscope (TEM), infrared (IR) and Raman spectroscopies confirmed the formation of NCs. We have demonstrated that the formation of Ag NPs accompanied with the degradation of surface fluorophores, which responded for the resolved absorption peak at ca. 346 nm and high luminescence of pristine CQDs. The NCs showed excellent antibacterial affinity to Escherichia coli. The results provide new understandings on the interactions between CQDs and silver ions as well as potential applications of Ag NP – CQD nanocomposites.

scholarly journals Biosynthesis of Silver Nanoparticles Using Juglans Regia Green Husk (Walnut) Water Extract and evaluation Antibacterial activity

2021 ◽  
Vol 3 (1) ◽  
pp. 90-102
Author(s):  
Zahra Izadiyan ◽  
Kamyar Shameli ◽  
Zahra Maghareh Esfahan ◽  
Siti Husnaa Mohd Taib ◽  
Pooneh Kia
Keyword(s):  
Antibacterial Activity ◽  
Zeta Potential ◽  
Juglans Regia ◽  
Water Extract ◽  
Diffusion Method ◽  
Ag Nps ◽  
High Antibacterial Activity ◽  
Vis Spectroscopy ◽  
Crystalline Nature ◽  
Zeta Potential Analysis

Biosynthesis of Ag-NPs at room temperature by using Juglans regia (J. regia) green husk extract which acts as reductant and stabilizer, simultaneously. The Ag/J. regia were characterized by using UV–visible, zeta potential, TEM, and AFM. Formation of Ag/ J. regia was determined by UV–vis spectroscopy, where absorption maxima surface plasmon at 400-460 nm. The zeta potential analysis indicated that J. regia green husk extract was negative and increasing in Ag/ J. regia. TEM images show the mean particle size was 31.37 nm with the standard deviation of 7.1 nm, where confirm by AFM measurements. The XRD study indicates the crystalline nature of the Ag-NPs. The antibacterial activity of Ag-NPs was investigated against Gram-positive and Gram-negative bacteria by the disc diffusion method were found to have high antibacterial activity. These results show that Ag-NPs can be useful in different biologic research and biomedical applications.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

Phytochemical Evaluation and Screening of Cardiotonic, Antibacterial and Anthelmintic Activities of Sida cordifolia L.

2014 ◽  
Vol 7 (3) ◽  
pp. 2567-2573
Author(s):  
Sarella Prakash Nathaniel Kumar ◽  
Kanthal L.K. ◽  
Durga S ◽  
Achutha Rama Raju D ◽  
Satyavati K
Keyword(s):  
Antibacterial Activity ◽  
Rural Areas ◽  
Anthelmintic Activity ◽  
Diffusion Method ◽  
Frog Heart ◽  
Aqueous Extracts ◽  
Cardiotonic Activity ◽  
Herbal Products ◽  
High Antibacterial Activity ◽  
Sida Cordifolia

Several herbs are traditionally used in the treatment of a variety of ailments particularly in the rural areas, where herbal medicine is mainly the source of health care system. Many of these herbs havenot been assessed for safety or toxicity to tissue or organs of the mammalian recipients. An attempt is made to prove the efficacy of Sida cordifolia Linn., (a traditional medicinal plant chosen on the basis of ethnomedical knowledge) for its Cardiotonic, Antibacterial and Anthelmintic activities. Sida cordofolia Linn., is used traditionally, inter alia, in the treatment of various infections, asthma, diarrhoea, heart and stomach disorders. Cardiotonicactivity is performed using isolated Frog Heart Perfusion Technique. Antibacterial activity of the whole plant extracts were assessed by Agar well diffusion method against the strains of Bacillus subtilis, Escherichia coli, and Staphylococcus aureus. Anthelmintic activity was studied against Pheretima posthuma. Phytochemical screening of powdered plant material revealed thepresence of some secondary metabolites such as alkaloids, saponins, tannins, glycosides and flavonoids. Results indicated that methanol, chloroform, aqueous extracts have significant cardiotonic activity but less than standard drugs. Methanol and Aqueous extracts showed high antibacterial activity and anthelmintic activity than the standard drugs. In a nutshell, we can conclude that the methanol and aqueous fractions of Sida cordifolia Linn., had a profound antibacterial and anthelmintic effect eventhough it possessed very significant cardiotonic activity. This validates its continuous usage in ethnomedicine. This plant could be developed into cheap, safe and culturally acceptable standardized herbal products and may serve as asource of new molecules for broad-spectrum antimicrobial and anthelmintic agent.

scholarly journals Influence of protein (human galectin-3) design on aspects of lectin activity

2020 ◽  
Vol 154 (2) ◽  
pp. 135-153 ◽  
Author(s):  
Gabriel García Caballero ◽  
Donella Beckwith ◽  
Nadezhda V. Shilova ◽  
Adele Gabba ◽  
Tanja J. Kutzner ◽  
...  
Keyword(s):  
Protein Design ◽  
Full Range ◽  
Biological Information ◽  
The Novel ◽  
Modular Assembly ◽  
Binding Partners ◽  
Galectin 3 ◽  
Potential Applications ◽  
Similar Affinity

Abstract The concept of biomedical significance of the functional pairing between tissue lectins and their glycoconjugate counterreceptors has reached the mainstream of research on the flow of biological information. A major challenge now is to identify the principles of structure–activity relationships that underlie specificity of recognition and the ensuing post-binding processes. Toward this end, we focus on a distinct feature on the side of the lectin, i.e. its architecture to present the carbohydrate recognition domain (CRD). Working with a multifunctional human lectin, i.e. galectin-3, as model, its CRD is used in protein engineering to build variants with different modular assembly. Hereby, it becomes possible to compare activity features of the natural design, i.e. CRD attached to an N-terminal tail, with those of homo- and heterodimers and the tail-free protein. Thermodynamics of binding disaccharides proved full activity of all proteins at very similar affinity. The following glycan array testing revealed maintained preferential contact formation with N-acetyllactosamine oligomers and histo-blood group ABH epitopes irrespective of variant design. The study of carbohydrate-inhibitable binding of the test panel disclosed up to qualitative cell-type-dependent differences in sections of fixed murine epididymis and especially jejunum. By probing topological aspects of binding, the susceptibility to inhibition by a tetravalent glycocluster was markedly different for the wild-type vs the homodimeric variant proteins. The results teach the salient lesson that protein design matters: the type of CRD presentation can have a profound bearing on whether basically suited oligosaccharides, which for example tested positively in an array, will become binding partners in situ. When lectin-glycoconjugate aggregates (lattices) are formed, their structural organization will depend on this parameter. Further testing (ga)lectin variants will thus be instrumental (i) to define the full range of impact of altering protein assembly and (ii) to explain why certain types of design have been favored during the course of evolution, besides opening biomedical perspectives for potential applications of the novel galectin forms.

scholarly journals Facile Synthesis and Characterization of Palm CNF-ZnO Nanocomposites with Antibacterial and Reinforcing Properties

2021 ◽  
Vol 22 (11) ◽  
pp. 5781
Author(s):  
Janarthanan Supramaniam ◽  
Darren Yi Sern Low ◽  
See Kiat Wong ◽  
Loh Teng Hern Tan ◽  
Bey Fen Leo ◽  
...  
Keyword(s):  
Plant Biomass ◽  
Cellulose Nanofibers ◽  
High Strength ◽  
Salmonella Typhi ◽  
Particle Sizes ◽  
Mechanical Reinforcement ◽  
Uniform Size ◽  
Preparation Methods ◽  
Potential Applications

Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites.

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