scholarly journals Investigating PLGA microparticle swelling behavior reveals an interplay of expansive intermolecular forces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Crystal E. Rapier ◽  
Kenneth J. Shea ◽  
Abraham P. Lee
Keyword(s):  
Predictive Modeling ◽  
Glycolic Acid ◽  
Intermolecular Forces ◽  
Swelling Behavior ◽  
Physiological Conditions ◽  
Size Dependent ◽  
Plga Microparticle ◽  
Swelling Capacity ◽  
High Throughput Manner ◽  
Index Size

AbstractThis study analyzes the swelling behavior of native, unmodified, spherically uniform, monodisperse poly(lactic-co-glycolic acid) (PLGA) microparticles in a robust high-throughput manner. This work contributes to the complex narrative of PLGA microparticle behavior and release mechanisms by complementing and extending previously reported studies on intraparticle microenvironment, degradation, and drug release. Microfluidically produced microparticles are incubated under physiological conditions and observed for 50 days to generate a profile of swelling behavior. Microparticles substantially increase in size after 15 days, continue increasing for 30 days achieving size dependent swelling indices between 49 and 83%. Swelling capacity is found to correlate with pH. Our study addresses questions such as onset, duration, swelling index, size dependency, reproducibility, and causal mechanistic forces surrounding swelling. Importantly, this study can serve as the basis for predictive modeling of microparticle behavior and swelling capacity, in addition to providing clues as to the microenvironmental conditions that encapsulated material may experience.

Effect of temperature and pH on swelling behavior of hydroxyethyl cellullose-acrylamide hydrogel

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Gabriel J. Alonso ◽  
José Luis A. Rivera ◽  
Ana María M. Mendoza ◽  
Maria Leonor H. Mendez
Keyword(s):  
Infrared Spectroscopy ◽  
Crosslinking Agent ◽  
Ph Sensitive ◽  
Swelling Behavior ◽  
Hydroxyethyl Cellulose ◽  
Effect Of Temperature ◽  
Swelling Capacity ◽  
Different Levels

AbstractThe swelling behavior of hydroxyethyl cellulose-acrylamide hydrogels at different pH and temperatures was studied. The absorption increased for the first 12 hours and then decreased. Several hydroxyethyl cellulose-acrylamide ratios were studied. Increasing hydroxyethyl cellulose amount decreased swelling, indicating that swelling was affected by increase in crosslinking. Three different levels of crosslinking agent were studied. Hydrogels exhibited a thermal and pH sensitive behaviour. Highest swelling capacity was found at pH 7.0 and 30 °C. All samples were characterized by means of infrared spectroscopy (FTIR). Characteristic absorbance peaks for both materials were found, showing the presence of hydroxyethyl cellulose and acrylamide on hydrogel.

scholarly journals Induction of Spermiation in Sterlet Acipenser ruthenus by PLGA Microparticle Delivery with Sustained Alarelin Release

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3305
Author(s):  
Peter Podhorec ◽  
Jindřiška Knowles ◽  
Jakub Vysloužil ◽  
Sergii Boryshpolets ◽  
Kateřina Kubová ◽  
...  
Keyword(s):  
Body Weight ◽  
Glycolic Acid ◽  
Saline Solution ◽  
Slow Release ◽  
Post Treatment ◽  
Sperm Production ◽  
Plga Microparticle ◽  
Acipenser Ruthenus ◽  
Optimal Effect ◽  
Sterlet Acipenser Ruthenus

Carp pituitary treatment versus poly (lactiac-co-glycolic acid) microparticles with slow release of Alarelin at 35 µg kg−1 or 200 µg kg−1 body weight to induce spermiation was compared in sterlet Acipenser ruthenus. All hormone treatments initially increased testosterone and 11-ketotestosterone, with a subsequent decline in testosterone but consistent high levels of 11-ketotestosterone at 48 and 72 h post-treatment. Spermiation did not differ between hormone-treated groups, and was not detected in controls receiving saline solution. Administration of the carp pituitary led to maximum sperm production 24 h post-treatment, followed by a decrease at 48 h post-treatment, with no sperm obtained at 72 h. The effect of Alarelin at 35 µg kg−1 bw and carp pituitary did not differ at 24 and 48 h post-treatment, whereas 200 µg kg−1 bw Alarelin was associated with significantly lower spermatozoon concentration 24 h post-treatment compared to carp pituitary, with no difference in milt volume. Higher relative sperm production was observed 48 h after injection of Alarelin at 200 µg kg−1 bw compared to carp pituitary. Spermatozoon motility was significantly higher in fish receiving Alarelin at 35 µg kg−1 bw than 200 µg kg−1 bw. The treatment with optimal effect on inducing spermiation was poly (lactic-co-glycolic acid) microparticles with slow release of Alarelin at 35 µg kg−1 bw.

scholarly journals Tough Hydrogels Based on Maleic Anhydride, Bulk Properties Study and Microfiber Formation by Electrospinning

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 972
Author(s):  
Faiza Bettahar ◽  
Fadila Bekkar ◽  
Leyre Pérez-Álvarez ◽  
Mohammed Issam Ferahi ◽  
Rachid Meghabar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Wound Healing ◽  
Maleic Anhydride ◽  
Swelling Behavior ◽  
Bulk Properties ◽  
Swelling Capacity ◽  
Maleic Anhydride Copolymers

Hydrogels present a great number of advantages, such as their swelling capacity or their capability to mimic tissues, which make them very interesting biomaterials. However, one of their main disadvantages is their lack of good mechanical properties, which could limit some of their applications. Several strategies have been carried out to develop hydrogels with enhanced mechanical properties, but many of the suggested synthetic pathways to improve this property are expensive and time consuming. In this work, we studied an easy synthetic path to produce tough hydrogels based on different maleic anhydride copolymers crosslinked with polyethylenglycol. The effect of the comonomers in the mechanical properties has been studied, their excellent mechanical properties, good swelling behavior and thermal stability being remarkable. In addition, in order to evaluate their possible applications as scaffolds or in wound healing applications, microsized fibers have been fabricated by electrospinning.

scholarly journals Swelling behavior and mechanical properties of Chitosan-Poly(N-vinyl-pyrrolidone) hydrogels

2020 ◽  
Vol 40 (7) ◽  
pp. 551-560
Author(s):  
Emil Budianto ◽  
Annissa Amalia
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Swelling Behavior ◽  
Interpenetrating Polymer Network ◽  
Vinyl Pyrrolidone ◽  
Simulated Gastric Fluid ◽  
Swelling Kinetics ◽  
Chitosan Hydrogel ◽  
Modified Chitosan ◽  
Swelling Capacity

AbstractIn this research, three modified chitosan-based hydrogels are synthesized, i.e., a crosslinked chitosan hydrogel and semi- and fully-interpenetrating polymer network (IPN) chitosan hydrogels fabricated using poly(N-vinyl-pyrrolidone). A non-modified chitosan hydrogel was also synthesized as a control. These samples were compared regarding their swelling behavior and mechanical properties. The hydrogels were characterized by Fourier Transform Infrared (FTIR) analysis and microscopy observations. The effect of crosslinking on the swelling capacity and on the swelling kinetics were evaluated in distilled water, simulated gastric fluid (SGF), and simulated intestinal fluid (SIF) at 37 °C, and the data were interpreted using various kinetic models. Finally, the mechanical properties were evaluated based on the tensile strength using a universal tensile testing machine. The results revealed that the swelling process conformed to the Schott model (pseudo-second-order kinetics), with Fickian diffusion as the diffusion mechanism type. The hydrogels all showed similar trends in their swelling kinetics. However, the full-IPN hydrogel exhibited the lowest equilibrium swelling capacity and the highest swelling rate. The mechanical test results indicate that the crosslinking model affects the resulting tensile strength.

Ultrastructure of Giant Mitochondria and Their Inclusions in Schwann Cells of Bovine Splenic Nerve

1974 ◽  
Vol 32 ◽  
pp. 194-195
Author(s):  
Å. Thureson-Klein
Keyword(s):  
Schwann Cells ◽  
Cell Organelles ◽  
Giant Mitochondria ◽  
Matrix Density ◽  
Physiological Conditions ◽  
Unmyelinated Axons ◽  
Internal Structures ◽  
Structural Abnormalities ◽  
Cytotoxic Compounds ◽  
Cell Components

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

Phase behavior of cationic and anionic surfactants at low concentrations

1992 ◽  
Vol 50 (1) ◽  
pp. 694-695
Author(s):  
E. Naranjo
Keyword(s):  
Phase Behavior ◽  
Structural Characterization ◽  
Dynamic Systems ◽  
Anionic Surfactants ◽  
Intermolecular Forces ◽  
Stable Form ◽  
Surfactant Mixtures ◽  
Low Concentrations ◽  
Cationic And Anionic Surfactants ◽  
General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

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