Particles In Nanometer Size Range Research Articles

Preparation of chelidonine highly loaded poly(lactide-co-glycolide)-based nanoparticles using a single emulsion method: Cytotoxic effect on MDA-MB-231 cell line

Introduction: Chelidonine, a bio-active component of Chelidonium majus, has been investigated for its anti-proliferative effects on various cancer cell lines with multidrug resistance (MDR). Although the results are auspicious, its poor water solubility and low bioavailability are the main limitations for clinical applications. This study aimed to develop poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with chelidonine, in order to enhance its bioavailability for oral administration and improve the therapeutic index. Methods: Herein, we encapsulated chelidonine in PLGA nanoparticles using a single emulsion solvent evaporation method. Nanoparticles were characterized in terms of size, surface charge and morphology, encapsulation efficiency, drug loading, and in vitro drug release profile. The anti-cancer efficacy of chelidonine-loaded nanoparticles and free chelidonine was evaluated in MDA-MB-231 breast cancer cells. Results: The physicochemical characteristics showed spherical particles in nanometer size range (263 ± 19.6 nm), with negative surface charge (−20.67 ± 2.48 mv), high encapsulation efficiency (76.53 ± 3.61%), and drug loading (22.47 ± 0.09%), as well as drug release amount of 60.27±5.68% up to 10 days. Furthermore, chelidonine-loaded nanoformulations were found to improve anti-cancer potential, compared with unentrapped chelidonine. Conclusion: This in vitro study showed that the encapsulation of chelidonine, as a potent herbal drug, in a polymeric matrix enhances its bioavailability. This offers an efficient vehicle for targeted drug delivery in cancer treatment.

Development, in-vitro and in-vivo characterization of gelatin nanoparticles for delivery of an anti-inflammatory drug

The present investigation involves the preparation of gelatin nanoparticles laden with naproxen, an anti-inflammatory drug. The nanoparticulate formulations were prepared by a modified two step desolvation technique upon varying the crosslinking ratio with drug and polymer and were assessed for their analgesic and anti-inflammatory activities. Particles of nanometer size range were formulated (177 ± 2.17–142 ± 2.06 nm) and the size distribution was monodisperse in the entire prepared batches with low polydispersity index. Entrapment efficiency of the nanoformulations was from 65 to 42%. DSC thermograms reported molecular level dispersion of drug in the nanoparticles whilst FTIR studies exhibited no drug-polymer interaction. Batches (NGP1-NGP8) exhibited an initial burst release followed by controlled release of the drug, the Korsmeyer-Peppas showed better linearity and the formulations displayed non-Fickian drug release pattern. Investigations were executed to analyze the analgesic and anti-inflammatory effects of the optimized formulation. The drug loaded nanoparticles exhibited significant (P<0.05) analgesic activity (acetic acid induced abdominal constriction & tail flick test in mice) and anti-inflammatory activity (carrageenan induced rat paw edema) in comparison to marketed product.

A robust synthesis and characterization of superparamagnetic CoFe2O4 nanoparticles as an efficient and reusable catalyst for green synthesis of some heterocyclic rings

A robust synthesis for magnetic CoFe2O4 nanoparticles via a hydrothermal technique was investigated. The prepared magnetic nanoparticles were characterized using powder X‐ray diffraction, scanning, transmission and high‐resolution transmission electron microscopies, energy‐dispersive X‐ray and infrared spectroscopies, thermogravimetric analysis and vibrating sample magnetometry. Based on the obtained data, the prepared powder was composed of ultrafine particles in nanometer size range with highly homogeneous spherical shape and elemental composition. Moreover, the prepared magnetic CoFe2O4 nanoparticles were used as an efficient catalyst for green synthesis of tetrahydropyridines and pyrrole derivatives in excellent yields, with easy work‐up and purification of products by non‐chromatographic methods. The catalyst can be recovered for subsequent reactions and reused without any appreciable loss of activity. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Transport and electrodynamical coupling of nano-grains ejected from the Saturnian rings and their possible ionospheric signatures

Besides oxygen-bearing neutral gas and ions, the Saturnian rings could be a source of small dust particles of nano-meter size range. Electrostatic charging effect by photoemission and/or electron impact could lead to ejection of the nano-grains out of the ring plane by electromagnetic force. The orbital motion of low-velocity charged dust generated by mutual collision of the ring particles has been considered in previous work (Liu and Ip, [2014], ApJ, 786, 34.). In the present parametric study, the dust component produced by meteoroid bombardment is modelled. Depending on the plasma environment in the vicinity of the rings and the condition of electrostatic charging at the ring plane, the transport mechanism could be modulated by the sunlit angle on the ring plane. It is found that, besides negatively charged dust, positively charged nano-grains could play a potentially important role in transporting water into the mid-latitude region of the Saturnian ionosphere in both hemispheres. Positively charged tiny grains could be injected into low-inclination escape trajectories away from Saturn. In addition to the modification (depletion) of Saturn's ionospheric electron content, this gravito-electromagnetic mass transport effect might modulate the water loading mechanism associated with the quasi-periodic formation of the Great White Spots and the planet-circling storms in the northern hemisphere. The present sets of simulations also suggest that the correlation the H3+ emission pattern with the ring opacity distribution could be a consequence of a source mechanism in addition to quenching by the so-called “ring rain” effect.

Towards tunable size of silica particles from rice husk

Amorphous spherical silica particles were produced in a variety of sizes ranging from nanometer to micrometer from rice husk by varying the concentration of white rice husk from 0.7wt.% to 5.6wt.% in sodium hydroxide to form sodium silicate solutions. The effect of increased reaction temperature (65°C) and the addition of water on the size of silica particles was also studied. At low concentrations of white rice husk (0.7wt.% and 1.4wt.%), uni-modal silica particles in nanometer size range were produced while at higher concentrations (2.8wt.% and 5.6wt.%), bi- and tri-modal particles were produced, which were converted to uni- and bi-modal by changing the reaction conditions, i.e. water and temperature, respectively. X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy and atomic absorption spectroscopy were employed for the compositional analysis of white rice husk and sodium silicate solution. Scanning electron microscopy was used to study the morphology and particle size of silica while X-ray diffraction confirmed the amorphous state of silica particles. Surface area of silica particles was analyzed by using Brunauer–Emmett–Teller analysis.

Melting of Argon Cluster: Dependence of Caloric Curves on MD Simulation Parameters

We report on molecular dynamics simulations performed using microcanonical ensemble to predict the melting of argon particles in nanometer size range 10 nm and to investigate the effect of the time step integration. We use the Lennard- Jones potential functions to describe the interatomic interactions, and the results are evaluated by using caloric curves of the melting phenomenon. Thermodynamic properties, including the total energy, Lindemann parameter, kinetic and potential distribution’s functions, are used to characterize the melting process. The data shows bimodal behavior only in a certain interval of integration time step Δt, while the internal energy increases monotonically with the temperature. For the other time step values, the back bending disappears. We claim that negative specific heat is related to a possible decrease of entropy in an isolated system; this can be interpreted as a result of the internal interactions, especially attractive process and specific relaxation time.

Optimization of the hydrophobic domain in poly(ethylene oxide)-poly(ɛ-caprolactone) based nano-carriers for the solubilization and delivery of Amphotericin B

The aim of the study was to develop a polymeric nano-carrier based on methoxy poly(ethylene oxide)- b-poly(ɛ-caprolactone) (MePEO- b-PCL) for the optimum solubilization and delivery of Amphotericin B (AmB). For this purpose, MePEO- b-PCL block co-polymers containing palmitoyl substituent on PCL (at a 100% substitution level) were synthesized through preparation of substituted monomer, that is, α-palmitoyl-ɛ-caprolactone, and further ring opening polymerization of this monomer by methoxy PEO (5000 g mol −1) using stannous octoate as catalyst. Prepared block co-polymers were characterized for their molecular weight by 1H NMR and gel permeation chromatography, and assembled to polymeric nano-carriers. The self-assembly of synthesized MePEO- b-PPaCL to spherical particles of nanometer size range was shown by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The efficacy of nano-carriers formed from this structure (abbreviated as MePEO- b-PPaCL) in comparison to unmodified MePEO- b-PCL and those with benzyl and cholesteryl substituent on PCL (abbreviated as MePEO- b-PBCL and MePEO- b-PChCL, respectively) on the solubilization and hemolytic activity of AmB against rat red blood cells was assessed. Under identical conditions, the maximum solubilization of AmB was achieved by nano-carriers prepared from MePEO- b-PPaCL (436 μg/mL), followed by MePEO- b-PChCL (355 μg/mL), MePEO- b-PBCL (296 μg/mL) and MePEO- b-PCL (222 μg/mL). The hemolytic activity of AmB was reduced the most by its encapsulation in MePEO- b-PChCL nano-particles which showed only 7% hemolysis at 30 μg/mL AmB concentration. This was followed by MePEO- b-PCL nano-particles which illustrated 15% hemolysis, MePEO- b-PPaCL with 40% hemolysis and MePEO- b-PBCL with 60% hemolysis at 30 μg/mL AmB concentrations, respectively. In contrast Fungizone ® showed 90% hemolysis at 30 μg/mL AmB concentration. Based on the improved solubility and reduced hemolytic activity, the MePEO- b-PChCL nano-carriers are considered as optimum structures for AmB delivery.

Chemical Modification of Hydrophobic Block in Poly(Ethylene Oxide) Poly(Caprolactone) Based Nanocarriers: Effect on the Solubilization and Hemolytic Activity of Amphotericin B

The aim of this study was to develop methoxy poly(ethylene oxide)-b-poly(epsilon-caprolactone) (MePEO-b-PCL) containing stearyl (St) substituents on PCL, and assess the efficacy of nanocarriers formed from this structure in comparison to unmodified MePEO-b-PCL and those with carboxyl substitutes on PCL on the solubilization and delivery of Amphotericin B (AmB). Prepared block copolymers were characterized for their molecular weight by (1)H NMR and gel permeation chromatography. The self-assembly of synthesized MePEO-b-PStCL to spherical particles of nanometer size range was shown by dynamic light scattering as well as electron and atomic force microscopy. Encapsulated AmB showed a reduction in its hemolytic activity against rat red blood cells in comparison to the commercial formulation of AmB, Fungizone.

Lipid grafts of egg-box complex: a new supramolecular biovector for 5-fluorouracil delivery

An attempt was made to improve the pharmacokinetic behaviour of 5-fluorouracil (5-FU) by incorporating it into lipoprotein imitating synthetic carrier `supramolecular biovector (SMBV)' which is an important prerequisite for achieving its better therapeutic performance against cancer. The polysaccharide core of SMBVs was prepared by ionotropic gelation technique by cross-linking polyguluronate units in the alginate molecules with calcium ions to form so called `egg-box structure'. The formulation and process variables were optimized to obtain particles of nanometer size range. Hydrophobization was carried out by fatty-acylation on the surface followed by phospholipid coating. Palmitoyl polyethylene glycol (p-PEG) was anchored to impart stealth behaviour. The scanning electron microscopy showed discrete spheres of average diameter 748 nm. Polydispersity was estimated to be 0.37. Overall zeta potential was −21.3 mV. The drug loading capacity and encapsulation efficiency was found to be 10.0% and 97.9%, respectively. The release from drug solution (AP) followed zero-order kinetics. Higuchi release pattern was obtained for egg-box complex cores (AP1) while first-order pattern was followed for fatty acylated (AP2) and lipid coated cores before (AP3) and after p-PEG anchoring (AP4). The amount of drug liberated in 24 h was in the order AP>AP1>AP2>AP4>AP3. The release pattern obtained was a combined effect of drug diffusion through egg-box matrix as well as partitioning in hydrophobic layer and p-PEG layer around the SMBV. The stability study showed negligible leakage and no appreciable change in particle size upon storage at different temperatures which is an indication of good stability of SMBV formulation. The plasma clearance data revealed increase in circulation half-life of drug and bioavailability. Tissue distribution data obtained was a result of competitive uptake of formulations from tissue macrophages and lymphatics depending upon its surface characteristics and residence period in vascular system. The enhanced delivery of drug to lymphatics and improvement in its half-life render SMBVs useful for control of metastasis and tumour growth.

382-PA12 Prevalence and geographic distribution of HIV infection among outcare tuberculosis patients in Rio de Janeiro

An attempt was made to improve the pharmacokinetic behaviour of 5-fluorouracil (5-FU) by incorporating it into lipoprotein imitating synthetic carrier `supramolecular biovector (SMBV)' which is an important prerequisite for achieving its better therapeutic performance against cancer. The polysaccharide core of SMBVs was prepared by ionotropic gelation technique by cross-linking polyguluronate units in the alginate molecules with calcium ions to form so called `egg-box structure'. The formulation and process variables were optimized to obtain particles of nanometer size range. Hydrophobization was carried out by fatty-acylation on the surface followed by phospholipid coating. Palmitoyl polyethylene glycol (p-PEG) was anchored to impart stealth behaviour. The scanning electron microscopy showed discrete spheres of average diameter 748 nm. Polydispersity was estimated to be 0.37. Overall zeta potential was −21.3 mV. The drug loading capacity and encapsulation efficiency was found to be 10.0% and 97.9%, respectively. The release from drug solution (AP) followed zero-order kinetics. Higuchi release pattern was obtained for egg-box complex cores (AP1) while first-order pattern was followed for fatty acylated (AP2) and lipid coated cores before (AP3) and after p-PEG anchoring (AP4). The amount of drug liberated in 24 h was in the order AP>AP1>AP2>AP4>AP3. The release pattern obtained was a combined effect of drug diffusion through egg-box matrix as well as partitioning in hydrophobic layer and p-PEG layer around the SMBV. The stability study showed negligible leakage and no appreciable change in particle size upon storage at different temperatures which is an indication of good stability of SMBV formulation. The plasma clearance data revealed increase in circulation half-life of drug and bioavailability. Tissue distribution data obtained was a result of competitive uptake of formulations from tissue macrophages and lymphatics depending upon its surface characteristics and residence period in vascular system. The enhanced delivery of drug to lymphatics and improvement in its half-life render SMBVs useful for control of metastasis and tumour growth.