Assembly of Nanoparticles from Bioactive Peptides and Chitosan

2011 ◽  
Vol 1312 ◽  
Author(s):  
B. Hu ◽  
Q. R. Huang ◽  
X. X. Zeng
Keyword(s):  
Electrophoretic Mobility ◽  
Bioactive Peptides ◽  
Molecular Chain ◽  
Mass Ratio ◽  
Ph Values ◽  
Transmission Electron ◽  
Low Salt ◽  
Liquid Chromatography Tandem Mass ◽  
Positively Charged ◽  
Critical Ph

ABSTRACTAssembly of nanoparticles from bioactive peptides, caseinophosphopeptides (CPPs) and chitosan (CS) at physiological conditions and various CS/CPPs mass ratios have been systematically studied using a combination of turbidimetric titration, dynamic light scattering (DLS), electrophoretic mobility (zeta-potential) and transmission electron microscopy (TEM). Peptides, incorporated with CS forming nanoparticles, have already been prepared and identified using liquid chromatography-tandem mass spectrometry (LC-MS-MS). They are characteristic with different amount of clusters of phosphorylated seryl residues. At low salt concentration, an increase of CS/CPP mass ratio shifted the critical pHϕ1, which designated the formation of CS/CPP nanocomplexes, as well as pHmax, representing the neutralization of positive and negative charge to higher pH values. The peptide-polymer binding mechanism was analyzed according to the results of DLS, electrophoretic mobility, and TEM. First, negatively charged CPPs absorbed to positively charged CS molecular chain to form intrapolymer nanocomplexes saturated with CPPs (CPPNP). Then, the negatively charged CPPNP was bridged by added positively charged CS. Finally, novel nano-scaled spherical brushes were formed as additional CS molecule absorbed back to and bound the CPPNP. Phosphorylated groups in the CPPs might be the dominant sites for interaction with –NH3+ on the CS molecular chain.

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

Inward and outward dust acoustic cylindrical and spherical waves interaction in four-component dusty plasma with nonthermal ions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Uday Narayan Ghosh ◽  
Prasanta Chatterjee ◽  
Barjinder Kaur
Keyword(s):  
Dusty Plasma ◽  
Charged Dust ◽  
Dust Grains ◽  
Mass Ratio ◽  
Temperature Ratio ◽  
Spherical Waves ◽  
Dust Acoustic ◽  
Waves Interaction ◽  
Positively Charged ◽  
Different Time Scales

Abstract A theoretical investigation by an all-inclusive adaptation of the PLK strategy is carried out in order to study the inward and outward interaction between two cylindrical and spherical dust acoustic solitary waves (DASWs) in an unmagnetized dusty plasma consisting of nonthermal distributed ions, negatively and positively charged dust grains along with electrons featuring Boltzmann’s distribution. The interactions and collisions between two cylindrical and spherical geometries at different time scales are studied. Also the combined effects of the nonthermality of ions, ion to electron temperature ratio as well as mass ratio of positive to negative dust grains have been studied in detail on the phase shifts raised due to collision. It has been seen that the properties of the cooperation of DASWs in cylindrical and spherical shaped are distinct.

Acid-base effects on intestinal Na+ absorption and vesicular trafficking

2002 ◽  
Vol 283 (3) ◽  
pp. C971-C979 ◽  
Author(s):  
Alan N. Charney ◽  
Richard W. Egnor ◽  
Jesline Alexander-Chacko ◽  
Nicholas Cassai ◽  
Gurdip S. Sidhu
Keyword(s):  
Electron Microscopy ◽  
Apical Membrane ◽  
Ringer Solution ◽  
Vesicular Trafficking ◽  
Acid Base ◽  
Western Blots ◽  
Ph Values ◽  
Transmission Electron ◽  
Apical Membranes ◽  
Nhe Isoforms

We examined for vesicular trafficking of the Na+/H+ exchanger (NHE) in pH-stimulated ileal and CO2-stimulated colonic Na+absorption. Subapical vesicles in rat distal ileum were quantified by transmission electron microscopy at ×27,500 magnification. Internalization of ileal apical membranes labeled with FITC-phytohemagglutinin was assessed using confocal microscopy, and pH-stimulated ileal Na+ absorption was measured after exposure to wortmannin. Apical membrane protein biotinylation of ileal and colonic segments and Western blots of recovered proteins were performed. In ileal epithelial cells incubated in HCO[Formula: see text]/Ringer or HEPES/Ringer solution, the number of subapical vesicles, the relative quantity of apical membrane NHE isoforms 2 and 3 (NHE2 and NHE3, respectively), and apical membrane fluorescence under the confocal microscope were not affected by pH values between 7.1 and 7.6. Wortmannin did not inhibit pH-stimulated ileal Na+ absorption. In colonic epithelial apical membranes, NHE3 protein content was greater at a Pco 2 value of 70 than 21 mmHg, was internalized when Pco 2 was reduced, and was exocytosed when Pco 2 was increased. We conclude that vesicle trafficking plays no part in pH-stimulated ileal Na+absorption but is important in CO2-stimulated colonic Na+ absorption.

scholarly journals Polymerization of actin by positively charged liposomes.

1988 ◽  
Vol 106 (4) ◽  
pp. 1221-1227 ◽  
Author(s):  
A Laliberte ◽  
C Gicquaud
Keyword(s):  
Electron Microscopy ◽  
Direct Contact ◽  
Atp Hydrolysis ◽  
Actin Assembly ◽  
Liposome Membrane ◽  
Low Salt ◽  
Spectrofluorimetric Analysis ◽  
Positively Charged

By cosedimentation, spectrofluorimetry, and electron microscopy, we have established that actin is induced to polymerize at low salt concentrations by positively charged liposomes. This polymerization occurs only at the surface of the liposomes, and thus monomers not in direct contact with the liposome remain monomeric. The integrity of the liposome membrane is necessary to maintain actin in its polymerized state since disruption of the liposome depolymerizes actin. Actin polymerized at the surface of the liposome is organized into two filamentous structures: sheets of parallel filaments in register and a netlike organization. Spectrofluorimetric analysis with the probe N-pyrenyl-iodoacetamide shows that actin is in the F conformation, at least in the environment of the probe. However, actin assembly induced by the liposome is not accompanied by full ATP hydrolysis as observed in vitro upon addition of salts.

Crystalline phase transformation of colloidal cadmium sulfide nanocrystals

2017 ◽  
Vol 31 (06) ◽  
pp. 1750037
Author(s):  
M. Ghali ◽  
A. M. Eissa ◽  
M. M. Mosaad
Keyword(s):  
Phase Transformation ◽  
Optical Absorption ◽  
Crystalline Phase ◽  
Growth Conditions ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Ph Values ◽  
Transmission Electron

In this paper, we give a microscopic view concerning influence of the growth conditions on the physical properties of nanocrystals (NCs) thin films made of CdS, prepared using chemical bath deposition CBD technique. We show a crystalline phase transformation of CdS NCs from hexagonal wurtzite (W) structure to cubic zincblende (ZB) when the growth conditions change, particularly the solution pH values. This effect was confirmed using X-ray diffraction (XRD), transmission electron microscopy (TEM), optical absorption and photoluminescence (PL) measurements. The optical absorption spectra allow calculation of the bandgap value, [Formula: see text], where significant increase [Formula: see text]200 meV in the CdS bandgap when transforming from Hexagonal to Cubic phase was found.

Synthesis and Characterization of Ag-PILC Through the Formation of Ag@Montmorillonite Nanocomposite

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550031 ◽  
Author(s):  
Feng Rao ◽  
Shaoxian Song ◽  
Alejandro Lopez-Valdivieso
Keyword(s):  
Ag Nanoparticles ◽  
Silver Ions ◽  
Trisodium Citrate ◽  
X Ray Diffraction ◽  
Exchange Method ◽  
Ph Values ◽  
Transmission Electron ◽  
Bet Method ◽  
Novel Method

Ag pillared interlayered clays ( Ag -PILCs) were synthesized through a novel method, in which Ag nanoparticles were formed in montmorillonite interlayers. In this method, silver ions were first exchanged into montmorillonite interlayers, and then reduced into Ag nanoparticles by trisodium citrate at 100°C in aqueous solutions. The synthesized Ag @montmorillonite nanocomposite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its surface area was evaluated by using Brunauer–Emmet–Teller (BET) method. Compared to traditional PILCs synthesized through ion exchange method, the formed Ag -PILCs had better thermal stability and stronger structure because their pillars are nanoparticles. Furthermore, this method introduces a possibility to control the size of the pillars and thus the pore size of the PILCs, due to that the nanoparticle pillars can be modified on their forms and diameters in the synthesizing process. Also, it was found that the intercalating Ag nanoparticle pillars were formed at restricted pH values and silver ion concentrations.

scholarly journals Core-shell Fe3O4@zeolite NaA as an Adsorbent for Cu2+

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5047
Author(s):  
Jun Cao ◽  
Peng Wang ◽  
Jie Shen ◽  
Qi Sun
Keyword(s):  
Adsorption Capacity ◽  
Adsorption Process ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
Transmission Electron ◽  
Monolayer Adsorption ◽  
Zeolite Naa ◽  
Infrared Spectrometer

Here, using Fe3O4@SiO2 as a precursor, a novel core-shell structure magnetic Cu2+ adsorbent (Fe3O4@zeolite NaA) was successfully prepared. Several methods, namely X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), Transmission electron microscope (TEM), Brunauer Emmett Teller (BET) and vibrating sample magnetometry (VSM) were used to characterize the adsorbent. A batch experiment was conducted to study the Cu2+ adsorption capacity of Fe3O4@zeolite NaA at different pH values, contact time, initial Cu2+ concentration and adsorbent does. It is found that the saturated adsorption capacity of Fe3O4@zeolite NaA on Cu2+ is 86.54 mg/g. The adsorption isotherm analysis shows that the adsorption process of Fe3O4@zeolite NaA to Cu2+ is more consistent with the Langmuir model, suggesting that it is a monolayer adsorption. Adsorption kinetics study found that the adsorption process of Fe3O4@zeolite NaA to Cu2+ follows the pseudo-second kinetics model, which means that the combination of Fe3O4@zeolite NaA and Cu2+ is the chemical chelating reaction. Thermodynamic analysis shows that the adsorption process of Fe3O4@zeolite NaA to Cu2+ is endothermic, with increasing entropy and spontaneous in nature. The above results show that Fe3O4@zeolite NaA is a promising Cu2+ adsorbent.

scholarly journals Effect of Nanoparticles Surface Charge on the Arabidopsis thaliana (L.) Roots Development and Their Movement into the Root Cells and Protoplasts

2019 ◽  
Vol 20 (7) ◽  
pp. 1650 ◽  
Author(s):  
Anna Milewska-Hendel ◽  
Maciej Zubko ◽  
Danuta Stróż ◽  
Ewa Kurczyńska
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Surface Charge ◽  
Physical Barrier ◽  
Root Cells ◽  
Plant Body ◽  
Transmission Electron ◽  
A Cell ◽  
Living Organisms ◽  
Positively Charged

Increasing usage of gold nanoparticles (AuNPs) in different industrial areas inevitably leads to their release into the environment. Thus, living organisms, including plants, may be exposed to a direct contact with nanoparticles (NPs). Despite the growing amount of research on this topic, our knowledge about NPs uptake by plants and their influence on different developmental processes is still insufficient. The first physical barrier for NPs penetration to the plant body is a cell wall which protects cytoplasm from external factors and environmental stresses. The absence of a cell wall may facilitate the internalization of various particles including NPs. Our studies have shown that AuNPs, independently of their surface charge, did not cross the cell wall of Arabidopsis thaliana (L.) roots. However, the research carried out with using light and transmission electron microscope revealed that AuNPs with different surface charge caused diverse changes in the root’s histology and ultrastructure. Therefore, we verified whether this is only the wall which protects cells against particles penetration and for this purpose we used protoplasts culture. It has been shown that plasma membrane (PM) is not a barrier for positively charged (+) AuNPs and negatively charged (−) AuNPs, which passage to the cell.

Changes in Size of Casein Micelles Caused by Growth of Psychrotrophic Bacteria in Raw Skim Milk

1984 ◽  
Vol 47 (1) ◽  
pp. 16-19 ◽  
Author(s):  
JONATHAN P. BURLINGAME-FREY ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Skim Milk ◽  
Bacterial Activity ◽  
Casein Micelles ◽  
Psychrotrophic Bacteria ◽  
Ph Values ◽  
Psychrotrophic Bacterium ◽  
Transmission Electron

Raw skim milk was inoculated (1%, v/v) with a proteolytic psychrotrophic bacterium that previously was isolated from milk. The inoculated skim milk was incubated at 7°C for 0, 3, 5 and 7 d. The pH values for the milk were 6.6, 6.5, 6.45 and 5.95, and the numbers of psychrotrophs/ml were 1.0 × 104 8.9 × 107, 9.0 × 108 and 2.5 × 108 for days 0, 3, 5 and 7, respectively. Samples of milk were negatively stained, examined with transmission electron microscopy and distribution of sizes of casein micelles was determined. The average and (mode) sizes of micelles were 849 (789), 1030 (634), 761 (634) and 405 (316) Angstroms for milks after days 0, 3, 5 and 7, respectively. Another set of samples was prepared from skim milk immediately after it was acidified to pH values of 6.6, 6.5, 6.45 and 5.95. The average and (mode) sizes of micelles were 891 (766), 875 (615), 913 (766) and 840 (615) Angstroms for milks having pH values of 6.6, 6.5, 6.45 and 5.95, respectively. Changes in size of micelles in the incubated samples resulted from bacterial activity other than small changes in pH.

scholarly journals Stability of Positively Charged Nanoemulsion Formulation Containing Steroidal Drug for Effective Transdermal Application

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Stephanie Da Costa ◽  
Mahiran Basri ◽  
Norashikin Shamsudin ◽  
Hamidon Basri
Keyword(s):  
Particle Size ◽  
Delivery System ◽  
Correlation Spectroscopy ◽  
Good Stability ◽  
Ph Values ◽  
Transdermal Application ◽  
Oil In Water ◽  
Steroid Drugs ◽  
Positively Charged ◽  
Dermal Application

This paper emphasizes the formation of a positively charged nanoemulsion system for steroid drugs (hydrocortisone). It is believed that positively charged nanoemulsion provides more effective penetration of the skin. Therefore in our study we focused on the incorporation of phytosphingosine which serves as a positively charged cosurfactant in the nanoemulsion system. Negatively charged nanoemulsions were formulated mainly for comparison. Freshly prepared formulations were formed with particle size less than 300 nm and showed good stability over time. The oil-in-water nanoemulsion also showed good viscosity, conductivity, and pH values. From TEM micrograph, particle size showed consistent results with the measurement using photon correlation spectroscopy. It was concluded that both positively and negatively charged nanoemulsions showed good stability and have great potential in transdermal delivery system. Though, further investigation of the drug release and drug penetration of both positively and negatively charged nanoemulsions will be studied to further prove the efficacy of nanoemulsion with hydrocortisone as a delivery system for dermal application.

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