scholarly journals Hybrid Vesicle Stability under Sterilisation and Preservation Processes Used in the Manufacture of Medicinal Formulations

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 914
Author(s):  
Rashmi Seneviratne ◽  
Lars J. C. Jeuken ◽  
Michael Rappolt ◽  
Paul A. Beales
Keyword(s):  
Block Copolymer ◽  
Colloidal Stability ◽  
Size Distributions ◽  
Process Stability ◽  
Vesicle Size ◽  
Industry Applications ◽  
Poly Ethylene ◽  
The Stability ◽  
Future Work ◽  
Vesicle Stability

Sterilisation and preservation of vesicle formulations are important considerations for their viable manufacture for industry applications, particular those intended for medicinal use. Here, we undertake an initial investigation of the stability of hybrid lipid-block copolymer vesicles to common sterilisation and preservation processes, with particular interest in how the block copolymer component might tune vesicle stability. We investigate two sizes of polybutadiene-block-poly(ethylene oxide) polymers (PBd12-PEO11 and PBd22-PEO14) mixed with the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) considering the encapsulation stability of a fluorescent cargo and the colloidal stability of vesicle size distributions. We find that autoclaving and lyophilisation cause complete loss of encapsulation stability under the conditions studied here. Filtering through 200 nm pores appears to be viable for sterilisation for all vesicle compositions with comparatively low release of encapsulated cargo, even for vesicle size distributions which extend beyond the 200 nm filter pore size. Freeze-thaw of vesicles also shows promise for the preservation of hybrid vesicles with high block copolymer content. We discuss the process stability of hybrid vesicles in terms of the complex mechanical interplay between bending resistance, stretching elasticity and lysis strain of these membranes and propose strategies for future work to further enhance the process stability of these vesicle formulations.

scholarly journals Hybrid Vesicle Stability under Sterilisation and Preservation Processes Used in the Manufacture of Medicinal Formulations

2020 ◽  
Author(s):  
Rashmi Seneviratne ◽  
Lars J.C. Jeuken ◽  
Michael Rappolt ◽  
Paul A. Beales
Keyword(s):  
Block Copolymer ◽  
Colloidal Stability ◽  
Size Distributions ◽  
Process Stability ◽  
Vesicle Size ◽  
Industry Applications ◽  
Poly Ethylene ◽  
The Stability ◽  
Future Work ◽  
Vesicle Stability

Sterilisation and preservation of vesicle formulations are an important consideration for their viable manufacture for industry applications, particular those intended for medicinal use. Here we undertake an initial investigation of the stability of hybrid lipid – block copolymer vesicles to common sterilisation and preservation processes, with particular interest in how the block copolymer component might tune vesicle stability. We investigate two sizes of polybutadiene-block-poly(ethylene oxide) polymers (PBd12-PEO11 and PBd22-PEO14) mixed with the phospholipid POPC considering the encapsulation stability of a fluorescent cargo and the colloidal stability of vesicle size distributions. We find that autoclaving and lyophilisation cause complete loss of encapsulation stability under the conditions studied here. Filtering through 200 nm pores appears to be viable for sterilisation for all vesicle compositions with comparatively low release of encapsulated cargo, even for vesicle size distributions which extend beyond the 200 nm filter pore size. Freeze-thaw of vesicles also shows promise for preservation of hybrid vesicles with high block copolymer content. We discuss the process stability of hybrid vesicles in terms of the complex mechanical interplay between bending resistance, stretching elasticity and lysis strain of these membranes and propose strategies for future work to further enhance the process stability of these vesicle formulations.

pH-responsive microspheres encapsulated with iron oxide nanoaggregates for gastrointestinal delivery

2012 ◽  
Vol 27 (1) ◽  
pp. 54-66 ◽  
Author(s):  
Young Ju Son ◽  
Hyuk Sang Yoo
Keyword(s):  
Iron Oxide ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Diblock Copolymer ◽  
Ph Responsive ◽  
Polymeric Microspheres ◽  
Intestinal Delivery ◽  
Poly Ethylene ◽  
The Stability

Block copolymer-stabilized iron oxide nanoaggregates were fabricated into pH-responsive polymeric microspheres for intestinal delivery of the magnetic nanoaggregates. A diblock copolymer consisted of methoxy poly(ethylene glycol) (mPEG) and poly(e-caprolactone) (PCL) was synthesized by ring-opening polymerization. Microspheres, consisted of Eudragit L100-55 encapsulate and stabilized magnetic nanoaggregates, were prepared by an oil-in-oil emulsification technique. The magnetization of the microspheres decreased, and the stability of the magnetic nanoaggregates in aqueous solutions increased as the amount of block copolymers in the microspheres increased. The encapsulated magnetic nanoaggregates were visualized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The encapsulation efficiency of nanoaggregates of the microspheres increased as the amount of diblock copolymer in the nanoaggregates was increased. The in vitro experiments confirmed the pH-dependent release of the nanoaggregates from the microspheres. The microspheres were administered to the animals by oral gavages, and the nanoaggregates in small intestines were visualized by histological examination of intestinal inner walls. Higher amounts of the block copolymer in the nanoaggregates increased the uptake efficiency in the intestinal tissues. Thus, the incorporation of the block copolymers in the magnetic nanoaggregates increased the intestinal absorption of the aggregates and Eudragit microspheres and effectively protected the nanoaggregates at low pH conditions of the stomach area.

Highly stable Au nanoparticles with double hydrophilic block copolymer templates: correlation between structure and stability

2017 ◽  
Vol 8 (31) ◽  
pp. 4528-4537 ◽  
Author(s):  
Eunyong Seo ◽  
Sang-Ho Lee ◽  
Sangho Lee ◽  
Soo-Hyung Choi ◽  
Craig J. Hawker ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Block Copolymer ◽  
Acrylic Acid ◽  
Colloidal Stability ◽  
Au Nanoparticles ◽  
Synthetic Method ◽  
Au Nps ◽  
Double Hydrophilic Block Copolymers ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

We herein report a facile synthetic method for preparing gold nanoparticles (Au NPs) with superior colloidal stability using a series of double hydrophilic block copolymers (DHBC), poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA), as a template (Au@DHBC NPs).

scholarly journals Morphological transition of amphiphilic block copolymer/PEGylated phospholipid complexes induced by the dynamic subtle balance interactions in the self-assembled aggregates

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 242-253
Author(s):  
Susu Tao ◽  
Yanyan Chu ◽  
Zihao Wang ◽  
Xiaoyan Xu ◽  
Qinggang Tan
Keyword(s):  
Polyethylene Glycol ◽  
Block Copolymer ◽  
Mixed Micelles ◽  
Morphological Structure ◽  
Repulsive Force ◽  
Morphological Transition ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
The Stability ◽  
Methoxy Polyethylene Glycol

AbstractRecently, there has been an increasing interest in the control of morphological transition of block copolymer aggregates. Here, we report how to control the morphological transition of methoxy polyethylene glycol–poly(d,l-lactic acid) (PDLLA–MPEG) by adding 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] (DSPE–PEG). In the aggregates formed by dialyzing DSPE–PEG/PDLLA–MPEG mixed solutions against water, the two hydrophobic fatty acid tails of DSPE–PEG will preferentially anchor to the hydrophobic segment end of PDLLA–MPEG by interdigitating between these two tails and PDLLA segments. Consequently, DSPE–PEG and PDLLA–MPEG will form “ABA” temporary supra-amphiphiles in which A represents a poly(ethylene glycol) (PEG) chain segment and B is a mixed hydrophobic segment composed of PDLLA and DSPE segments; the repulsive force derived from the PEG segments of DSPE–PEG can affect the stability of “ABA” temporary supra-amphiphiles. Our results show that the dynamic subtle balance between the number of “ABA” temporary supra-amphiphiles formed and the strength of repulsive force between the PEG segments of DSPE–PEG drives the morphological structure of DSPE–PEG/PDLLA–MPEG aggregates to change from micelles to vesicles, then to semi-vesicles and finally to mixed micelles, with increasing DSPE–PEG additions.

scholarly journals Hot-Wire Laser-Directed Energy Deposition: Process Characteristics and Benefits of Resistive Pre-Heating of the Feedstock Wire

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 634
Author(s):  
Agnieszka Kisielewicz ◽  
Karthikeyan Thalavai Pandian ◽  
Daniel Sthen ◽  
Petter Hagqvist ◽  
Maria Asuncion Valiente Bermejo ◽  
...  
Keyword(s):  
Heat Input ◽  
Energy Deposition ◽  
Fine Tuning ◽  
Hot Wire ◽  
Process Stability ◽  
Electrical Signals ◽  
Melt Pool ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
The Stability

This study investigates the influence of resistive pre-heating of the feedstock wire (here called hot-wire) on the stability of laser-directed energy deposition of Duplex stainless steel. Data acquired online during depositions as well as metallographic investigations revealed the process characteristic and its stability window. The online data, such as electrical signals in the pre-heating circuit and images captured from side-view of the process interaction zone gave insight on the metal transfer between the molten wire and the melt pool. The results show that the characteristics of the process, like laser-wire and wire-melt pool interaction, vary depending on the level of the wire pre-heating. In addition, application of two independent energy sources, laser beam and electrical power, allows fine-tuning of the heat input and increases penetration depth, with little influence on the height and width of the beads. This allows for better process stability as well as elimination of lack of fusion defects. Electrical signals measured in the hot-wire circuit indicate the process stability such that the resistive pre-heating can be used for in-process monitoring. The conclusion is that the resistive pre-heating gives additional means for controlling the stability and the heat input of the laser-directed energy deposition.

Periodic Solutions in Rotor Dynamic Systems With Nonlinear Supports: A General Approach

1989 ◽  
Vol 111 (2) ◽  
pp. 187-193 ◽  
Author(s):  
C. Nataraj ◽  
H. D. Nelson
Keyword(s):  
Dynamic Systems ◽  
Original Problem ◽  
Squeeze Film ◽  
Algebraic Equations ◽  
Trigonometric Collocation ◽  
Nonlinear Algebraic Equations ◽  
The Stability ◽  
Future Work ◽  
Rotor Dynamic ◽  
Large Rotor

A new quantitative method of estimating steady state periodic behavior in nonlinear systems, based on the trigonometric collocation method, is outlined. A procedure is developed to analyze large rotor dynamic systems with nonlinear supports by the use of the above method in conjunction with Component Mode Synthesis. The algorithm discussed is seen to reduce the original problem to solving nonlinear algebraic equations in terms of only the coordinates associated with the nonlinear supports and is a big improvement over commonly used integration methods. The feasibility and advantages of the procedure so developed are illustrated with the help of an example of a typical rotor dynamic system with an uncentered squeeze film damper. Future work on the investigation of the stability of the periodic response so obtained is outlined.

Glucose-Responsive Hybrid Nanoassemblies in Aqueous Solutions: Ordered Phenylboronic Acid within Intermixed Poly(4-hydroxystyrene)-block-poly(ethylene oxide) Block Copolymer

2015 ◽  
Vol 16 (12) ◽  
pp. 3731-3739 ◽  
Author(s):  
Alicja Matuszewska ◽  
Mariusz Uchman ◽  
Agnieszka Adamczyk-Woźniak ◽  
Andrzej Sporzyński ◽  
Stergios Pispas ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Ethylene Oxide ◽  
Aqueous Solutions ◽  
Phenylboronic Acid ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

A study on emulsion stabilization induced with linear and cyclized polystyrene-poly(ethylene oxide) block copolymer surfactants

2015 ◽  
Vol 47 (5) ◽  
pp. 408-412 ◽  
Author(s):  
Eisuke Baba ◽  
Toshiaki Yatsunami ◽  
Takuya Yamamoto ◽  
Yasuyuki Tezuka
Keyword(s):  
Block Copolymer ◽  
Ethylene Oxide ◽  
Poly Ethylene Oxide ◽  
Emulsion Stabilization ◽  
Poly Ethylene
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