scholarly journals An Advanced Lyophilization Toward Intact Lipid Nanovesicles: Liquid-mediated Freezing With Cryoprotectant to Retain the Integrity of Lipid Nanovesicles

2021 ◽  
Author(s):  
Eunhye Yang ◽  
Hyunjong Yu ◽  
SungHak Choi ◽  
Kyung-Min Park ◽  
Ho-Sup Jung ◽  
...  
Keyword(s):  
Storage Stability ◽  
Average Diameter ◽  
Freezing Rate ◽  
Core Material ◽  
Size Distributions ◽  
Uniform Size ◽  
Original Activity ◽  
Lipid Nanocarriers ◽  
Optimal Medium ◽  
Intact Lipid

Abstract A novel lyophilization method using liquid-mediated freezing (LMF) with cryoprotectant (CPA) was designed to achieve intact lipid nanovesicles after lyophilization. During the freezing step, CPA prevented water supercooling, and the freezing rate was controlled by LMF. Regulating the freezing rate by various liquid media was a crucial determinant of membrane disruption, and isopropanol (freezing rate of 0.933°C/min) was the optimal medium for the LMF system. Lyophilized lipid nanovesicle using both LMF and CPA retained 92.9% of the core material and had uniform size distributions (Z-average diameter = 135.5 nm, polydispersity index = 0.074), similar to intact vesicles (112.3 nm and 0.184, respectively), after rehydration. Only lyophilized lipid nanovesicle using both LMF and CPA showed no changes in membrane fluidity and polarity. This lyophilization method can be applied to improve storage stability of lipid nanocarriers encapsulating drugs such as a mRNA vaccine, while retaining its original activity.

scholarly journals Controlled rate slow freezing with lyoprotective agent to retain the integrity of lipid nanovesicles during lyophilization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eunhye Yang ◽  
Hyunjong Yu ◽  
SungHak Choi ◽  
Kyung-Min Park ◽  
Ho-Sup Jung ◽  
...  
Keyword(s):  
Storage Stability ◽  
Average Diameter ◽  
Freezing Rate ◽  
Slow Freezing ◽  
Core Material ◽  
Size Distributions ◽  
Uniform Size ◽  
Original Activity ◽  
Lipid Nanocarriers ◽  
Optimal Medium

AbstractWe designed a novel lyophilization method using controlled rate slow freezing (CSF) with lyoprotective agent (LPA) to achieve intact lipid nanovesicles after lyophilization. During the freezing step, LPA prevented water supercooling, and the freezing rate was controlled by CSF. Regulating the freezing rate by various liquid media was a crucial determinant of membrane disruption, and isopropanol (freezing rate of 0.933 °C/min) was the optimal medium for the CSF system. Lyophilized lipid nanovesicle using both CSF and LPA retained 92.9% of the core material and had uniform size distributions (Z-average diameter = 133.4 nm, polydispersity index = 0.144), similar to intact vesicles (120.7 nm and 0.159, respectively), after rehydration. Only lyophilized lipid nanovesicle using both CSF and LPA showed no changes in membrane fluidity and polarity. This lyophilization method can be applied to improve storage stability of lipid nanocarriers encapsulating drugs while retaining their original activity.

Synthesis of LiCoO2 particles with tunable sizes by a urea-based-homogeneous-precipitation method

2020 ◽  
Vol 111 (4) ◽  
pp. 347-355
Author(s):  
Munekazu Motoyama ◽  
Hiroki Iwasaki ◽  
Miyuki Sakakura ◽  
Takayuki Yamamoto ◽  
Yasutoshi Iriyama
Keyword(s):  
Size Distribution ◽  
Average Diameter ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
Homogeneous Precipitation Method ◽  
Wide Range ◽  
Size Uniformity ◽  
Average Size ◽  
Uniform Size Distribution

Abstract This paper reports the synthesis of monodisperse spherical LiCoO2 particles in a wide range of average diameter using a urea-based-uniform-precipitation method. The average diameter of LiCoO2 particles can be varied from 2 to 14 lm with a uniform size distribution. The effective approach to maintain the size uniformity while changing the average size of LiCoO2 particles is to keep the ratio of [CO(NH2)2] to [CoSO4] at 8 even when the CoSO4 and urea concentrations are changed.

scholarly journals The thermal and electrical conductivity of a single crystal of aluminium

1927 ◽  
Vol 115 (770) ◽  
pp. 236-241 ◽  
Keyword(s):  
Electrical Conductivity ◽  
Single Crystals ◽  
Test Specimen ◽  
Average Diameter ◽  
National Physical Laboratory ◽  
Present Communication ◽  
Uniform Size ◽  
The Third ◽  
Physical Laboratory

The recent work of Carpenter and Elam on the growth of single crystals of large dimensions has rendered possible the study of the physical constants of single crystals of the commoner metals, and the present communication describes the determination of the thermal and electrical conductivity of aluminium in the form of an isolated crystal. The form of the crystal investigated is shown in fig. 1. This crystal had been prepared at the National Physical Laboratory employing the technique described by Carpenter in “Nature,” p. 266, August 21, 1926, which briefly is as follows:— The test specimen is machined and subjected to three treatments, thermal, mechanical, and thermal. The first treatment is necessary to soften the metal completely and produce new equiaxed crystals of so far as possible uniform size, the average diameter being 1/150 inch. The second consists in straining these crystals to the required amount, and the third in heating the strained crystals to the requisite temperature, so that the potentiality of growth conferred by strain could be brought fully into operation.

scholarly journals Electrospun Multiple-Chamber Nanostructure and Its Potential Self-Healing Applications

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2413 ◽  
Author(s):  
Yubo Liu ◽  
Xinkuan Liu ◽  
Ping Liu ◽  
Xiaohong Chen ◽  
Deng-Guang Yu
Keyword(s):  
Electron Microscope ◽  
Electrochemical Corrosion ◽  
Average Diameter ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Uniform Size ◽  
Transmission Electron ◽  
Reactive Fluids ◽  
Amine Curing ◽  
First Time

To address the life span of materials in the process of daily use, new types of structural nanofibers, fabricated by multifluid electrospinning to encapsulate both epoxy resin and amine curing agent, were embedded into an epoxy matrix to provide it with self-healing ability. The nanofibers, which have a polyacrylonitrile sheath holding two separate cores, had an average diameter of 300 ± 140 nm with a uniform size distribution. The prepared fibers had a linear morphology with a clear three-chamber inner structure, as verified by scanning electron microscope and transmission electron microscope images. The two core sections were composed of epoxy and amine curing agents, respectively, as demonstrated under the synergistic characterization of Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry. The TGA results disclosed that the core-shell nanofibers contained 9.06% triethylenetetramine and 20.71% cured epoxy. In the electrochemical corrosion experiment, self-healing coatings exhibited an effective anti-corrosion effect, unlike the composite without nanofibers. This complex nanostructure was proven to be an effective nanoreactor, which is useful to encapsulate reactive fluids. This engineering process by multiple-fluid electrospinning is the first time to prove that this special multiple-chamber structure has great potential in the field of self-healing.

Frozen-State Storage Stability of a Monoclonal Antibody: Aggregation is Impacted by Freezing Rate and Solute Distribution

2013 ◽  
Vol 102 (4) ◽  
pp. 1194-1208 ◽  
Author(s):  
Maria A. Miller ◽  
Miguel A. Rodrigues ◽  
Matthew A. Glass ◽  
Satish K. Singh ◽  
Keith P. Johnston ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Storage Stability ◽  
Solute Distribution ◽  
Freezing Rate ◽  
Frozen State

Immobilization of Lipase on MCM-41 Nanospheres: Exploring the Effects of Supports Morphology on the Lipase Immobilization

2013 ◽  
Vol 634-638 ◽  
pp. 987-990
Author(s):  
Wei Wei Zhang ◽  
Shao Yi Jia ◽  
Song Hai Wu ◽  
Jing Wei Hou
Keyword(s):  
Storage Stability ◽  
Lipase Immobilization ◽  
Original Activity ◽  
Spherical Morphology ◽  
And Storage ◽  
Mcm 41

In this study, the effects of the supports morphology on the lipase immobilization were discussed. PVA-MCM-41 with perfect spherical morphology, which was synthesized in the presence of PVA, was introduced to compare with MCM-41 which is irregular in shape and aggregate seriously. The amount of lipase immobilized on PVA-MCM-41 was a little higher than that immobilized on MCM-41. However, the activity of the former is just around 50% of the latter. The lipase immobilized on PVA-MCM-41 exhibited well reusability and storage stability that it remained 27% of its original activity after using for 6 times and 44% after being stored for 33 days. To the lipase immobilized on MCM-41, it declined to 8% by using just 3 times and 35% after 33 days.

Preparation and Characterization of Hollow TiOX Nano-Spheres for Electrophoretic Displays

2009 ◽  
Vol 79-82 ◽  
pp. 385-388 ◽  
Author(s):  
Ting Feng Tan ◽  
Shi Rong Wang ◽  
Shu Guang Bian ◽  
Xiang Gao Li
Keyword(s):  
Methyl Methacrylate ◽  
Large Scale ◽  
Hollow Spheres ◽  
Average Diameter ◽  
Core Shell ◽  
Hollow Core ◽  
Uniform Size ◽  
Tio2 Sample ◽  
Latex Particles ◽  
The Core

Hollow TiOX nano-spheres have been successfully prepared using hollow core-shell latex particles as template, which involves the deposition of inorganic coating on the surface of hollow core-shell latex particles and subsequent removal of the latex particles by calcinations in air or ammonia gas. The formation route of hollow core-shell polymer particles is presented as follows: Firstly, poly-methyl methacrylate (PMMA) seed emulsions are prepared as the 'core'. Subsequently, the outer shell poly(styrene-co-methyl methacrylate) (PS-co-MMA) particles wrap on the surface of the core, the microspheres with core-shell have been prepared. Finally, Ti(OBu)4 is used as precursor for the preparation of hollow TiOX nanospheres. Transmission electron microscopy (TEM) and atom force microscopy (AFM) images of seed emulsions show they have the uniform size of about 470 nm. TEM of hollow core-shell polymers particles show they have an average diameter of about 500 nm. X-ray diffraction (XRD) analysis of TiO2 sample calcined presents that the strong absorptions is coordinated with the standard chart of rutile TiO2. TEM of TiO2 and TiO show hollow spheres well-dispersed with the diameter range of 300-400 nm and 350-400 nm, respectively. The density (in the atmospheric pressure, 20 °C) of TiO2 and TiO hollow spheres was 2.49 and 2.37 g∙mL-1, respectively. The Zeta potentials were 6.20 mV and 20.39 mV, respectively. Uniform hollow spheres show low density and good electrophoretic displays. The electrophoretic mobilities of white TiO2 and black TiO hollow spheres in tetrachloroethylene show they are suitable for electronic paper as background and display particles, respectively. It is anticipated that this method would present a potential toward the road of large-scale industrial production of TiOx hollow spheres.

Optimization of Processing Conditions and Properties of Epoxy Microcapsule

2014 ◽  
Vol 654 ◽  
pp. 11-15
Author(s):  
Xiu Lan Cai ◽  
Da Tian Fu ◽  
Ai Lan Qu
Keyword(s):  
Average Diameter ◽  
Decomposition Temperature ◽  
Core Material ◽  
Formaldehyde Resin ◽  
Core Shell ◽  
Agitation Rate ◽  
Processing Conditions ◽  
Mass Ratio ◽  
Shell Mass ◽  
Optimum Processing

A series of microcapsules were prepared by interfacial polymerization method using epoxy and urea formaldehyde resin as core material and shell material, individually. The effects of processing conditions on the properties of epoxy microcapsules were systematically investigated based on w(Core), average diameter and decomposition temperature of microcapsules through the method of orthographic factorial design and the most optimum processing conditions were included. The results indicated that core/shell mass ratio was the most important factor on w(Core), average diameter and decomposition temperature of microcapsules. The optimum processing conditions were concluded: 1:1 for the core/shell mass ratio, 300 rpm for agitation rate and 0.8% DBS as emulsifier. The microcapsules prepare in the optimum processing conditions were well encapsuled and presented thin shell and smooth surface. Moreover, the addition of 10% microcapsules can improve the mechanical properties of epoxy matrix greatly.

scholarly journals Synthesis of functional magnetic porous SrFe12O19/P(St-DVB-MAA) microspheres by a novel suspension polymerization

2008 ◽  
Vol 6 (4) ◽  
pp. 627-633 ◽  
Author(s):  
Sifang Kong ◽  
Jiang Cheng ◽  
Yangsheng Liu ◽  
Xiufang Wen ◽  
Pihui Pi ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Suspension Polymerization ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Conductometric Titration ◽  
Average Diameter ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Porous Microspheres ◽  
Magnetic Porous Microspheres

AbstractIn this study, a novel and effective suspension polymerization has been employed to prepare functional magnetic porous SrFe12O19/P(St-DVB-MAA) microspheres in the presence of bilayer surfactants (sodium dodecyl benzene sulfonate (SDBS) and oleic acid (OA)) coated on micro-size magnetic SrFe12O19. This was achieved by pre-polymerizing the organic phase, which contained co-monomers, porogens and treated magnetic particles, at 65°C for 0.5 h under ultrasound conditions. Aqueous solutions containing a dispersion agent were then added to effect suspension polymerization. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and magnetic property measurement system (MPMS) were used to characterize the functional magnetic porous microspheres. The results show that the microparticles are well shaped with a uniform size distribution of about 0.5 ∼ 0.7 mm and the surfaces of the microspheres have many micro-pores with an average diameter of 0.533 µm. There are carboxyl groups (−COOH) on the surface of the microspheres to the extent of 0.65 mmol g−1, as determined by conductometric titration. According to the XRD spectra, iron oxide consists mainly of SrFe12O19 which reveals hexahedral structure. The content of magnetic SrFe12O19 reaches 17.81% (by mass), and the microspheres have good heat resistance. The magnetic porous microspheres are ferromagnetic with high residual magnetization and coercivity, 21.59 emu g−1 and 4.13 kOe, respectively. The saturation magnetisation is around 42.85 emu g−1.

scholarly journals Characterization of Moringa oleifera Leaf Powder Extract Encapsulated in Maltodextrin and/or Gum Arabic Coatings

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3044
Author(s):  
Toyosi T. George ◽  
Ayodeji B. Oyenihi ◽  
Fanie Rautenbach ◽  
Anthony O. Obilana
Keyword(s):  
Moringa Oleifera ◽  
Water Solubility ◽  
Storage Stability ◽  
Gum Arabic ◽  
Slight Modification ◽  
High Water ◽  
Core Material ◽  
Tap Density ◽  
Leaf Powder ◽  
Processing And Storage

The encapsulation of bioactive-rich plant extracts is an effective method of preventing their damage or loss of activity during processing and storage. Here, the techno-functional properties of microcapsules developed from Moringa oleifera leaf powder (MoLP) extract (core) with maltodextrin (MD), gum Arabic (GA), and a combination (MDGA) (coatings) were assessed. The bulk and tap density were 0.177, 0.325 and 0.297 g/mL and 0.13, 0.295 and 0.259 g/mL for GA, MD and MDGA microcapsules, respectively. Flowability properties of microcapsules indicated an intermediate flow except for GA which had a poor flow. The moisture content of the microcapsules ranged from 1.47% to 1.77% with no significant differences (p > 0.05) observed. All the microcapsules had high water solubility (86.35% for GA to 98.74% for MD and 90.51% for MDGA). Thermogravimetric analyses revealed that encapsulation enhanced the thermal stability of the core material. The X-ray diffraction analysis revealed that the microcapsules and extracts have an amorphous nature, which was validated by the surface morphology analysis that showed amorphous, irregular, and flake-like attributes except for MDGA microcapsules which had slightly spherical and agglomerated surfaces. The Fourier Transform Infra-Red spectra of the microcapsules showed the presence of C-O and O-H aromatic rings as well as amine groups. New spectra were observed at 1177, 1382 and 1411 cm−1 for MDGA, MD and GA, respectively, after encapsulation, which connotes a slight modification in the chemical structural pattern after encapsulation. Storage stability tests (28 days at 4, 25 and 40 °C) showed that the microcapsules were most stable at 4 °C and the stability differs significantly (p ≤ 0.05) with coating material type and temperature with MDGA showing better storage stability than others. Altogether, the attributes of the MDGA microcapsules were comparatively better than either MD or GA alone. The present data, therefore, demonstrate an effective encapsulation process for MoLP extract that can serve as fortificants in processed food products where MoLP may be used.

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