scholarly journals Controlled Synthesis of Triangular Silver Nanoplates by Gelatin–Chitosan Mixture and the Influence of Their Shape on Antibacterial Activity

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 873 ◽  
Author(s):  
Quoc Khuong Vo ◽  
Duc Duy Phung ◽  
Quynh Nhu Vo Nguyen ◽  
Hong Hoang Thi ◽  
Nhat Hang Nguyen Thi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Critical Role ◽  
High Yield ◽  
Synthesis Process ◽  
Silver Nanostructures ◽  
Experimental Conditions ◽  
Silver Nanoplates ◽  
Triangular Silver Nanoplates ◽  
Ft Ir

Triangular silver nanoplates were prepared by using the seeding growth approach with the presence of citrate-stabilized silver seeds and a mixture of gelatin–chitosan as the protecting agent. By understanding the critical role of reaction components, the synthesis process was improved to prepare the triangular nanoplates with high yield and efficiency. Different morphologies of silver nanostructures, such as triangular nanoplates, hexagonal nanoprisms, or nanodisks, can be obtained by changing experimental parameters, including precursor AgNO3 volume, gelatin–chitosan concentration ratios, and the pH conditions. The edge lengths of triangular silver nanoplates were successfully controlled, primarily through the addition of silver nitrate under appropriate condition. As-prepared triangular silver nanoplates were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-Vis, Fourier transform infrared spectroscopy (FT-IR), and X-Ray diffraction (XRD). Silver nanoplates had an average edge length of 65–80 nm depending on experimental conditions and exhibited a surface plasma resonance absorbance peak at 340, 450, and 700 nm. The specific interactions of gelatin and chitosan with triangular AgNPs were demonstrated by FT-IR. Based on the characterization, the growth mechanism of triangular silver nanoplates was theoretically proposed regarding the twinned crystal of the initial nanoparticle seeds and the crystal face-blocking role of the gelatin–chitosan mixture. Moreover, the antibacterial activity of triangular silver nanoplates was considerably improved in comparison with that of spherical shape when tested against Gram-positive and Gram-negative bacteria species, with 6.0 ug/mL of triangular silver nanoplates as the MBC (Minimum bactericidal concentration) for Escherichia coli and Vibrio cholera, and 8.0 ug/mL as the MBC for Staphylococcus aureus and Pseudomonas aeruginosa. The MIC (Minimum inhibitory concentration) of triangular Ag nanoplates was 4.0 ug/mL for E. coli, V. cholera, S. aureus, and P. aeruginosa.

scholarly journals Hydroxyapatite-ciprofloxacin delivery system: Synthesis, characterisation and antibacterial activity

2018 ◽  
Vol 68 (2) ◽  
pp. 129-144 ◽  
Author(s):  
Maria-Viorica Ciocilteu ◽  
Andreea Gabriela Mocanu ◽  
Adriana Mocanu ◽  
Catalin Ducu ◽  
Oana Elena Nicolaescu ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Diffusion Controlled ◽  
Ft Ir ◽  
Inhibition Zones ◽  
Bacterial Growth Inhibition ◽  
Local Release

Abstract The main objective of this study was to synthesize hydroxyapatite-ciprofloxacin composites using a chemical precipitation method and to evaluate the properties and in vitro release profile of the drug from the hydroxyapatite-ciprofloxacin composites. Composite characterization was achieved by FT-IR, XRD and DLS. Ciprofloxacin determination was accomplished by HPLC, resulting in good incorporation efficiency of the drug (18.13 %). The in vitro release study (Higuchi model C = K t1/2 and Ritger-Peppas model, C = K t0.6) showed a diffusion-controlled mechanism. The antibacterial activity showed that the bacterial growth inhibition zones were approximately equal for the synthesis composites and for the mechanical mixture on the Staphylococcus aureus germ. The use of hydroxyapatite, which is a biocompatible, bioactive and osteoconductive material, with ciprofloxacin, which has good antibacterial activity in this composite, makes it suitable for the development of bone grafts. Furthermore, the synthesis process allows a slow local release of the drug.

scholarly journals Aromatic Hydroxyl Group Plays a Critical Role in Antibacterial Activity of the Curcumin Analogues

2012 ◽  
Vol 7 (1) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Mi Kyoung Kim ◽  
Jun Cheol Park ◽  
Youhoon Chong
Keyword(s):  
Antibacterial Activity ◽  
Critical Role ◽  
Antibacterial Activities ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Hydroxyl Group ◽  
Curcumin Analogues ◽  
Structure Activity ◽  
Relationship Study

The aim of this study was to investigate the role of the aromatic substituents of the curcumin scaffold on the antibacterial activity of the resulting curcumin analogues. Six curcumin analogues with different aromatic substituents were prepared and their antibacterial activities were evaluated against two Gram-positive and four Gram-negative bacteria. The structure-activity relationship study demonstrated that antibacterial activity of the curcumin analogues was critically dependent upon the aromatic hydroxyl group. Thus, hydroxycurcumin with an additional aromatic hydroxyl group on the curcumin scaffold showed antibacterial activity against all six pathogens tested and it remained effective even against ampicillin-resistant Enterobacter cloacae. Along with the previously reported antioxidative effect, the broad-spectrum antibacterial activity of the hydroxycurcumin warrants further investigation of its biological activity as well as extensive structure-activity relationship study of the curcumin analogues with various aromatic substituents.

Critical Role of Polystyrene Layer on Plasmonic Silver Nanoplates in Organic Photovoltaics

2019 ◽  
Vol 2 (4) ◽  
pp. 2475-2485 ◽  
Author(s):  
Jonathan S. Metzman ◽  
Assad U. Khan ◽  
Brenden A. Magill ◽  
Giti A. Khodaparast ◽  
James R. Heflin ◽  
...  
Keyword(s):  
Organic Photovoltaics ◽  
Critical Role ◽  
Silver Nanoplates

Neutrophils play a critical role in development of LPS-induced airway disease

2002 ◽  
Vol 283 (5) ◽  
pp. L952-L962 ◽  
Author(s):  
Jordan D. Savov ◽  
Stephen H. Gavett ◽  
David M. Brass ◽  
Daniel L. Costa ◽  
David A. Schwartz
Keyword(s):  
Transforming Growth Factor ◽  
Critical Role ◽  
Recovery Period ◽  
Exposure Period ◽  
Airway Disease ◽  
Transforming Growth Factor Β1 ◽  
Experimental Conditions ◽  
Control Serum ◽  
Inhalation Challenge

We investigated the role of neutrophils in the development of endotoxin-induced airway disease via systemic neutrophil depletion of C3H/HeBFeJ mice and coincident inhalation challenge with lipopolysaccharide (LPS) over a 4-wk period. Mice were made neutropenic with intraperitoneal injections of neutrophil antiserum before and throughout the exposure period. Experimental conditions included LPS-exposed, antiserum-treated; LPS-exposed, control serum-treated; air-exposed, antiserum-treated; and air-exposed, control serum-treated groups. Physiological, biological, and morphological assessments were performed after a 4-wk exposure and again after a 4-wk recovery period. After the 4-wk exposure, LPS-induced inflammation of the lower airways was significantly attenuated in the neutropenic mice, although airway responsiveness (AR) to methacholine (MCh) remained unchanged. After the recovery period, LPS-exposed neutrophil-replete mice had increased AR to MCh when compared with the LPS-exposed neutropenic animals. Morphometric data indicate that the 4-wk exposure to LPS leads to a substantial expansion of the subepithelial area of the medium-sized airways (90–129 μm diameter) in nonneutropenic mice but not neutropenic mice, and this difference persisted even after the recovery period. Expression of bronchial epithelial and subepithelial transforming growth factor-β1 (TGF-β1) was diminished in the challenged neutropenic mice compared with the neutrophil-sufficient mice. These studies demonstrate that neutrophils play a critical role in the development of chronic LPS-induced airway disease.

Application of Response Surface Methodology for Improving the Yield of 1,5-bis(ptoluenesulfonyl)- 3,7-Dihydroxyoctahydro-1,5-Diazocine

2019 ◽  
Vol 16 (3) ◽  
pp. 398-404 ◽  
Author(s):  
Yang Zou ◽  
Jingyi Fei ◽  
Liangzhe Chen ◽  
Qingfeng Dong ◽  
Houbin Li
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Raw Materials ◽  
Low Cost ◽  
Product Yield ◽  
Synthesis Process ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Simple Method ◽  
Ft Ir

Background: 3,3,7,7-tetrakis (difluoramino) octahydro-1,5-dinitro-1,5-diazocine (HNFX), as an important oxidizer in propellants, has received much attention due to its high density and energy. However, there are many difficulties that need to be solved, such as complex synthetic processes, low product yield, high cost of raw materials and complicated purification. In the synthesis of HNFX, the intermediate named 1,5-bis (p-toluenesulfonyl)-3,7-dihydroxyoctahydro-1, 5-diazocine (gem-diol), is difficult to synthesize. Methods: A simple method was used to synthesize the gem-diol. This prepared gem-diol was characterized by FT-IR, 1H NMR, melting point and mass spectrometry. In order to increase the yield of gem-diol, response surface methodology (RSM) was introduced to optimize experimental conditions. Results: After the establishment of the model, the optimal conditions of synthesis were found to be 9.33h for reaction time, 6.13wt. % for the concentration of NaOH and 1.38:1 for ratio of ECH (p-toluenesulfonamide): TCA (epichlorohydrin). Under the optimal conditions, the experimental value and the predicted value of yield were 22.18% and 22.92%, respectively. Conclusion: 1,5-bis (p-toluenesulfonyl)-3,7-dihydroxyoctahydro-1,5-diazocine (gem-diol) can be synthesized using the low cost of chemical materials, including p-toluenesulfonamide, epichlorohydrin, sodium hydroxide and ethanol. Response surface methodology (RSM) is an effective method to optimize the synthesis process, thereby improving the yield of gem-diol.

scholarly journals Detection of regularities in a random environment

2020 ◽  
Vol 73 (12) ◽  
pp. 2106-2118
Author(s):  
Arnaud Rey ◽  
Louisa Bogaerts ◽  
Laure Tosatto ◽  
Guillem Bonafos ◽  
Ana Franco ◽  
...  
Keyword(s):  
Statistical Learning ◽  
Contextual Information ◽  
Critical Role ◽  
Naming Task ◽  
Variable Number ◽  
Experimental Conditions ◽  
Human Participants ◽  
New Evidence ◽  
Repetition Task

Regularity detection, or statistical learning, is regarded as a fundamental component of our cognitive system. To test the ability of human participants to detect regularity in a more ecological situation (i.e., mixed with random information), we used a simple letter-naming paradigm in which participants were instructed to name single letters presented one at a time on a computer screen. The regularity consisted of a triplet of letters that were systematically presented in that order. Participants were not told about the presence of this regularity. A variable number of random letters were presented between two repetitions of the regular triplet, making this paradigm similar to a Hebb repetition task. Hence, in this Hebb-naming task, we predicted that if any learning of the triplet occurred, naming times for the predictable letters in the triplet would decrease as the number of triplet repetitions increased. Surprisingly, across four experiments, detection of the regularity only occurred under very specific experimental conditions and was far from a trivial task. Our study provides new evidence regarding the limits of statistical learning and the critical role of contextual information in the detection (or not) of repeated patterns.

scholarly journals The Critical Role of Aromatic-Aromatic Drug-Polymer Interactions to Provide Nanomedicines Containing Chloroquine: A Simple Proposal to Provide High Encapsulation, High Stability, and Prolonged Drug Release

2020 ◽  
Author(s):  
María Gabriela Villamizar-Sarmiento ◽  
Ignacio Moreno-Villoslada ◽  
Felipe Oyarzun-Ampuero
Keyword(s):  
Chronic Diseases ◽  
Drug Loading ◽  
Critical Role ◽  
Molar Ratio ◽  
High Yield ◽  
Prolonged Release ◽  
Aromatic Group ◽  
Aromatic Interactions ◽  
Very High

Abstract Background: Chloroquine (CQ) is a drug commonly used to treat malaria. CQ has also gained interest for the treatment of other chronic diseases such as arthritis, lupus, cancer, diabetes, atherosclerosis, and dermatomyositis, among others. Since CQ is hydrophilic and low molecular-weight, attractive interactions with polymers in aqueous medium are weaker than with water, so that low encapsulation together with uncontrolled and fast release is observed. Importantly, a long-term administration of CQ is suggested, thus the development of formulations with controlled and prolonged release is desirable. Results: Here we propose the use of aromatic interactions between the cationic CQ and the FDA approved polymer poly(sodium 4-styrenesulfonate) (PSS) for the formation and stabilization of nanoparticles (NPs). The strategy consists on the simple mixture of two aqueous solutions containing the oppositelly charged molecules. UV-vis and NMR spectroscopy evidence intimate aromatic-aromatic interactions between CQ and PSS. CQ/PSS molar ratios from 0.2 to 0.5 allow obtaining NPs with spherical shape, size in the range of 170-410 nm, zeta potential from -18 to -45 mV, and particles number in the range of 0.9 - 6.6 x 1010 NPs/mL. Selected NPs (CQ/PSS molar ratio 0.4) are stable to wide variations in ionic strength (0-200 mM), pH (2-10) and temperature (20-50 °C). In addition, CQ/polymer 0.4 was also tested but with the absence of the aromatic group in the polymer, and providing smaller (70 nm), lower-concentrated (6.1 x 109 NPs/mL), and unstable particles, confirming the key role of the aromatic group. Furthermore, CQ/PSS NPs are stable during months and can be converted to a reconstitutable powder. Importantly, the selected NPs (CQ/PSS 0.4) show full drug association efficiency (100 %), very high drug loading (49 %), very high yield (89 %), and evidencing a drug entrapment/release governed by kinetic associations (≈99 %). Finally, release studies evidence a controlled and prolonged delivery. Conclusions: Considering the potential uses of CQ for chronic diseases, and the simplicity and efficiency of our proposal, it could be considered as a valuable alternative to developed nanomedicines. In addition, this strategy could be used for other drugs and polymers showing similar characteristics to CQ and PSS.

Rapid and high yield production of phospholipids enriched in CLA via acidolysis: The critical role of the enzyme immobilization protocol

2019 ◽  
Vol 296 ◽  
pp. 123-131 ◽  
Author(s):  
Carlos M. Verdasco-Martín ◽  
Carlos Corchado-Lopo ◽  
Roberto Fernández-Lafuente ◽  
Cristina Otero
Keyword(s):  
Enzyme Immobilization ◽  
Critical Role ◽  
High Yield ◽  
Yield Production ◽  
High Yield Production

scholarly journals Do birds disperse mosses? Evidence of endozoochory in upland geese Chloephaga picta and white-bellied seedsnipes Attagis malouinus in sub-Antarctic Chile

2021 ◽  
Author(s):  
Xenabeth Lazaro ◽  
Roy Mackenzie ◽  
Jaime Jimènez
Keyword(s):  
Peat Soil ◽  
Critical Role ◽  
Bird Species ◽  
Ex Situ ◽  
Experimental Conditions ◽  
Polytrichum Strictum ◽  
Upland Goose ◽  
Bird Feces

Birds are known to act as potential vectors for the exogenous dispersal of bryophyte diaspores. Given the totipotency of vegetative tissue of many bryophytes, birds could also contribute to endozoochorous bryophyte dispersal. Research has shown that fecal samples of the upland goose (Chloephaga picta) and white-bellied seedsnipe (Attagis malouinus) contain bryophyte fragments. Although few fragments from bird feces have been known to regenerate, the evidence for the viability of diaspores following passage through the bird intestinal tract remains ambiguous. We evaluated the role of endozoochory in these same herbivorous and sympatric bird species in sub-Antarctic Chile. We hypothesized that fragments of bryophyte gametophytes retrieved from their feces are viable and capable of regenerating new plant tissue. Eleven feces disc samples containing undetermined moss fragments from C. picta (N=6) and A. malouinus (N=5) and six moss fragment samples from wild collected mosses (Conostomum tetragonum, Syntrichia robusta, and Polytrichum strictum) were grown ex situ in peat soil and in vitro using a agar-Gamborg medium. After 91 days, 20% of fragments from A. malouinus feces, 50% of fragments from C. picta feces, and 67% of propagules from wild mosses produced new growth. The fact that moss diaspores remained viable and can regenerate under experimental conditions following the passage through the intestinal tracts of these robust fliers and altitudinal and latitudinal migrants, suggests that sub-Antarctic birds may play a critical role in bryophyte dispersal. This relationship may have important implications in the way bryophytes disperse and colonize habitats facing climate change. Keywords: birds, bryophyte dispersal, endozoochory, mosses, sub-Antarctic

Site of Lysosome Production During Hepatic Injury

1969 ◽  
Vol 27 ◽  
pp. 348-349
Author(s):  
Nalin J. Unakar
Keyword(s):  
Electron Microscopy ◽  
Golgi Apparatus ◽  
Mouse Liver ◽  
Hepatic Injury ◽  
Close Approximation ◽  
Experimental Conditions ◽  
Toxic Injury

The increased number of lysosomes as well as the close approximation of lysosomes to the Golgi apparatus in tissue under variety of experimental conditions is commonly observed. These observations suggest Golgi involvement in lysosomal production. The role of the Golgi apparatus in the production of lysosomes in mouse liver was studied by electron microscopy of liver following toxic injury by CCI4.

Sign in / Sign up

Export Citation Format

Share Document