scholarly journals Synthesis and Characterization of Nanomaterial Based on Halloysite and Hectorite Clay Minerals Covalently Bridged

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 506
Author(s):  
Marina Massaro ◽  
Cesar Viseras Iborra ◽  
Giuseppe Cavallaro ◽  
Carmelo Giuseppe Colletti ◽  
Fátima García-Villén ◽  
...  
Keyword(s):  
External Surface ◽  
Silver Ions ◽  
Halloysite Nanotubes ◽  
Exchange Capacity ◽  
Covalent Modification ◽  
Proof Of Concept ◽  
Adsorption Ability ◽  
Cp Mas Nmr ◽  
Straightforward Approach

Halloysite is an aluminosilicate clay with a predominantly hollow tubular structure (HNTs) able to act as a nanocontainer for the encapsulation of several chemicals. However, HNTs possess low affinity for metal ions in their pristine form and they need to be modified for improving their adsorption capabilities. Therefore, to overcome this issue herein we report a straightforward approach for the covalent modification of the external surface of halloysite nanotubes with hectorite clay. Compared to halloysite, hectorite possesses a lamellar structure with higher cation exchange capacity. The covalent linkage between the two clays was verified by several techniques (FTIR spectroscopy, 13C CP-MAS NMR, TGA, ζ−potential, DLS, and XRD measurements) and the morphology was imaged by TEM investigations. As proof of concept the adsorption ability of the obtained nanomaterial in comparison to pristine clays was proved using ciprofloxacin and silver ions chosen as models for their different chemical characteristics.

scholarly journals Antibacterial Activity of Amine-Functionalized Silver-Loaded Natural Zeolite Clinoptilolite

2021 ◽  
Vol 15 (1) ◽  
pp. 13
Author(s):  
Nik Ahmad Nizam Nik Malek ◽  
Siti Aishah Mohd Hanim
Keyword(s):  
Antibacterial Activity ◽  
Natural Zeolite ◽  
Metal Ion ◽  
Silver Ions ◽  
Exchange Capacity ◽  
Carrier System ◽  
Amine Functionalized ◽  
Inhibition Concentration ◽  
Diffusion Technique

The antibacterial activity of amine-functionalized silver-loaded natural zeolite clinoptilolite was analysed against Gram-negative Escherichia coli ATCC 11229 and a comparison was made with raw clinoptilolite, silver-loaded clinoptilolite, and amine-functionalized clinoptilolite with APTES (3-Aminopropyl) triethoxysilane. Results from the characterization of the samples using Fourier transform infrared (FTIR) spectroscopy showed that the silver-loaded clinoptilolite was functionalized with APTES without affecting the original framework structure of the clinoptilolite. The antibacterial activity of the analysed samples based on disc diffusion technique (DDT) and minimum inhibition concentration (MIC) showed that the silver-loaded clinoptilolite (150 % of cation exchange capacity of clinoptilolite) had the highest antibacterial activity, as compared to amine-functionalized silver-loaded zeolite. This study showed that the functionalization of silver-loaded clinoptilolite could affect the release and action of silver ions to kill or inhibit bacterial growth. However, it showed that the natural zeolite clinoptilolite could become a good carrier system for the antibacterial metal ion, especially silver ions.   Keywords: Zeolite, clinoptilolite, antibacterial agent, silver, amine-functionalization    

Development and Characterization of Amine-Clay Hybrid Adsorbents for CO2 Capture

2016 ◽  
Vol 1133 ◽  
pp. 547-551 ◽  
Author(s):  
Ali E.I. Elkhalifah ◽  
Mohammad Azmi Bustam ◽  
Azmi Mohd Shariff ◽  
Sami Ullah ◽  
Nadia Riaz ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Surface Properties ◽  
Molar Mass ◽  
Adsorption Ability ◽  
Stepwise Increase ◽  
Inverse Effect ◽  
Bet Method ◽  
Sodium Form

The present work aims at a better understanding of the influences of the intercalated mono-, di- and triethanolamines on the characteristics and CO2 adsorption ability of sodium form of bentonite (Na-bentonite). The results revealed that the molar mass of intercalated amines significantly influenced the structural and surface properties as well as the CO2 adsorption capacity of Na-bentonite. In this respect, a stepwise increase in the d-spacing of Na-bentonite with the molar mass of amine was recorded by XRD technique. However, an inverse effect of the molar mass of amine on the surface area was confirmed by BET method. CO2 adsorption experiments on amine-bentonite hybrid adsorbents showed that the CO2 adsorption capacity inversly related to the molar mass of amine at 25 ͦC and 101 kPa. Accordingly, Na-bentonite modified by monoethanolammonium cations adsorbed as high as 0.475 mmol CO2/g compared to 0.148 and 0.087 mmol CO2/g for that one treated with di- and triethanolammonium cations, respectively.

scholarly journals An engineered IL-2 reprogrammed for anti-tumor therapy using a semi-synthetic organism

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jerod L. Ptacin ◽  
Carolina E. Caffaro ◽  
Lina Ma ◽  
Kristine M. San Jose Gall ◽  
Hans R. Aerni ◽  
...  
Keyword(s):  
Nk Cells ◽  
Large Scale ◽  
Tumor Therapy ◽  
Covalent Modification ◽  
Synthetic Dna ◽  
Expansion Characteristic ◽  
Synthetic Organisms ◽  
Dose Dependent ◽  
Receptor Beta

AbstractThe implementation of applied engineering principles to create synthetic biological systems promises to revolutionize medicine, but application of fundamentally redesigned organisms has thus far not impacted practical drug development. Here we utilize an engineered microbial organism with a six-letter semi-synthetic DNA code to generate a library of site-specific, click chemistry compatible amino acid substitutions in the human cytokine IL-2. Targeted covalent modification of IL-2 variants with PEG polymers and screening identifies compounds with distinct IL-2 receptor specificities and improved pharmacological properties. One variant, termed THOR-707, selectively engages the IL-2 receptor beta/gamma complex without engagement of the IL-2 receptor alpha. In mice, administration of THOR-707 results in large-scale activation and amplification of CD8+ T cells and NK cells, without Treg expansion characteristic of IL-2. In syngeneic B16-F10 tumor-bearing mice, THOR-707 enhances drug accumulation in the tumor tissue, stimulates tumor-infiltrating CD8+ T and NK cells, and leads to a dose-dependent reduction of tumor growth. These results support further characterization of the immune modulatory, anti-tumor properties of THOR-707 and represent a fundamental advance in the application of synthetic biology to medicine, leveraging engineered semi-synthetic organisms as cellular factories to facilitate discovery and production of differentiated classes of chemically modified biologics.

scholarly journals Characterization of design grammar of peptides for regulating liquid droplets and aggregates of FUS

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kiyoto Kamagata ◽  
Rika Chiba ◽  
Ichiro Kawahata ◽  
Nanako Iwaki ◽  
Saori Kanbayashi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Electrostatic Interactions ◽  
Amyloid Fibrils ◽  
Droplet Formation ◽  
Liquid Droplets ◽  
Proof Of Concept ◽  
Aggregate Formation ◽  
Fused In Sarcoma ◽  
Dynamics Simulations

AbstractLiquid droplets of aggregation-prone proteins, which become hydrogels or form amyloid fibrils, are a potential target for drug discovery. In this study, we proposed an experiment-guided protocol for characterizing the design grammar of peptides that can regulate droplet formation and aggregation. The protocol essentially involves investigation of 19 amino acid additives and polymerization of the identified amino acids. As a proof of concept, we applied this protocol to fused in sarcoma (FUS). First, we evaluated 19 amino acid additives for an FUS solution and identified Arg and Tyr as suppressors of droplet formation. Molecular dynamics simulations suggested that the Arg additive interacts with specific residues of FUS, thereby inhibiting the cation–π and electrostatic interactions between the FUS molecules. Second, we observed that Arg polymers promote FUS droplet formation, unlike Arg monomers, by bridging the FUS molecules. Third, we found that the Arg additive suppressed solid aggregate formation of FUS, while Arg polymer enhanced it. Finally, we observed that amyloid-forming peptides induced the conversion of FUS droplets to solid aggregates of FUS. The developed protocol could be used for the primary design of peptides controlling liquid droplets and aggregates of proteins.

scholarly journals Characterization of Ectophosphatase Activities in Trypanosomatid Parasites of Plants

2000 ◽  
Vol 90 (9) ◽  
pp. 1032-1038 ◽  
Author(s):  
P. M. L. Dutra ◽  
C. O. Rodrigues ◽  
A. Romeiro ◽  
L. A. M. Grillo ◽  
F. A. Dias ◽  
...  
Keyword(s):  
Lithium Fluoride ◽  
External Surface ◽  
Sodium Orthovanadate ◽  
Intact Cells ◽  
Phosphatase Activities ◽  
Cerium Phosphate ◽  
Cytochemical Analysis ◽  
Trypanosomatid Parasites ◽  
Phosphate Deposits

In the present work ectophosphatase activities of three trypanosomatid parasites of plants were characterized using intact cells. Phytomonas françai, Phytomonas mcgheei, and Herpetomonas sp. hydrolyzed p-nitro-phenylphosphate at a rate of 5.40, 7.28, and 25.58 nmol Pi/mg of protein per min, respectively. Experiments using classical inhibitors of acid phosphatases such as sodium orthovanadate (NaVO3) and sodium fluoride (NaF) showed a decrease in phosphatase activities. Lithium fluoride (LiF) and aluminum chloride (AlCl3) were also used. Although AlCl3 had no effect, LiF was able to promote a decrease in the phosphatase activities. Interestingly, the inhibition caused by LiF was enhanced by the addition of AlCl3 during the reaction, probably due to the formation of fluoroaluminate complexes. This effect was confirmed by cytochemical analysis. In this assay, electron-dense cerium phosphate deposits were visualized on the external surface of the three parasites.

Characterization of Silver Binding in Cryptomelane by X-ray Absorption Spectroscopy

1998 ◽  
Vol 524 ◽  
Author(s):  
R. Ravikumar ◽  
D. W. Fuerstenau ◽  
G. A. Waychunas
Keyword(s):  
Manganese Oxide ◽  
Silver Ions ◽  
Oxide Phase ◽  
Synthetic Sample ◽  
Temperature Spectrum ◽  
X Ray ◽  
Room Temperature Sample ◽  
X Ray Absorption ◽  
Temperature Sample

ABSTRACTUsing silver K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, two different samples of silver-containing manganese oxide were analyzed in the fluorescence mode. For the first sample, silver ions from solution were sorbed onto one synthetic manganese oxide phase, namely cryptomelane (KxMn8O16, where l<x<2). The second sample was a silvermanganese oxide from Colorado. From the EXAFS analysis, silver was found to occupy two different sites in the synthetic sample. The natural samples from Colorado also exhibited a very similar coordination distances as the synthetic samples. In the low temperature spectrum of the synthetic sample at 10 K, the Ag-O peak was found to be missing and the amplitude of the Ag- Ag peak was approximately three times larger than the corresponding room temperature sample.

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