Terahertz Spectroscopy: An investigation of the Structural Dynamics of Freeze-Dried PLGA Microspheres

2019 ◽  
Author(s):  
T S ◽  
Philippa J. Hooper ◽  
Gabi Kaminski ◽  
Christopher F. van der Walle ◽  
J. Axel Zeitler
Keyword(s):  
Freeze Drying ◽  
Large Scale ◽  
Terahertz Spectroscopy ◽  
Double Emulsion ◽  
Plga Microspheres ◽  
Terahertz Time Domain Spectroscopy ◽  
Freeze Dried ◽  
Oil In Water ◽  
Biodegradable Poly ◽  
Temperature Variable

Biodegradable poly lactic-co-glycolic acid (PLGA) microspheres can be used to encapsulate peptide and offer a promising drug delivery vehicle. In this work we investigate the dynamics of PLGA microspheres prepared by freeze-drying and the molecular mobility at lower temperatures leading to the glass transition temperature, using temperature-variable terahertz time-domain spectroscopy (THz-TDS) experiments. The microspheres were prepared using a water-in-oil-in-water (w/o/w) double emulsion technique and subsequent freeze-drying of the samples. Physical characterisation was performed by morphology measurements, scanning electron microscopy (SEM), and helium pycnometry. The THz-TDS data show two distinct transition processes, T<sub>g,β</sub> in the range of 167-219 K, associated with local motions, and T<sub>g,α</sub> in the range of 313-330 K associated with large-scale motions, for the microspheres examined. Using FTIR measurements in the mid-infrared we were able to characterise the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined T<sub>g,β</sub> and T<sub>g,α</sub> and free volume and microsphere dynamics. <br>

Terahertz Spectroscopy: An investigation of the Structural Dynamics of Freeze-Dried PLGA Microspheres

2019 ◽  
Author(s):  
T S ◽  
Philippa J. Hooper ◽  
Gabi Kaminski ◽  
Christopher F. van der Walle ◽  
J. Axel Zeitler
Keyword(s):  
Freeze Drying ◽  
Large Scale ◽  
Terahertz Spectroscopy ◽  
Double Emulsion ◽  
Plga Microspheres ◽  
Terahertz Time Domain Spectroscopy ◽  
Freeze Dried ◽  
Oil In Water ◽  
Biodegradable Poly ◽  
Temperature Variable

Biodegradable poly lactic-co-glycolic acid (PLGA) microspheres can be used to encapsulate peptide and offer a promising drug delivery vehicle. In this work we investigate the dynamics of PLGA microspheres prepared by freeze-drying and the molecular mobility at lower temperatures leading to the glass transition temperature, using temperature-variable terahertz time-domain spectroscopy (THz-TDS) experiments. The microspheres were prepared using a water-in-oil-in-water (w/o/w) double emulsion technique and subsequent freeze-drying of the samples. Physical characterisation was performed by morphology measurements, scanning electron microscopy (SEM), and helium pycnometry. The THz-TDS data show two distinct transition processes, T<sub>g,β</sub> in the range of 167-219 K, associated with local motions, and T<sub>g,α</sub> in the range of 313-330 K associated with large-scale motions, for the microspheres examined. Using FTIR measurements in the mid-infrared we were able to characterise the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined T<sub>g,β</sub> and T<sub>g,α</sub> and free volume and microsphere dynamics. <br>

Terahertz Spectroscopy: An investigation of the Structural Dynamics of Freeze-Dried PLGA Microspheres

2019 ◽  
Author(s):  
T S ◽  
Philippa J. Hooper ◽  
Gabi Kaminski ◽  
Christopher F. van der Walle ◽  
J. Axel Zeitler
Keyword(s):  
Freeze Drying ◽  
Large Scale ◽  
Terahertz Spectroscopy ◽  
Double Emulsion ◽  
Plga Microspheres ◽  
Terahertz Time Domain Spectroscopy ◽  
Freeze Dried ◽  
Oil In Water ◽  
Biodegradable Poly ◽  
Temperature Variable

Biodegradable poly lactic-co-glycolic acid (PLGA) microspheres can be used to encapsulate peptide and offer a promising drug delivery vehicle. In this work we investigate the dynamics of PLGA microspheres prepared by freeze-drying and the molecular mobility at lower temperatures leading to the glass transition temperature, using temperature-variable terahertz time-domain spectroscopy (THz-TDS) experiments. The microspheres were prepared using a water-in-oil-in-water (w/o/w) double emulsion technique and subsequent freeze-drying of the samples. Physical characterisation was performed by morphology measurements, scanning electron microscopy (SEM), and helium pycnometry. The THz-TDS data show two distinct transition processes, T<sub>g,β</sub> in the range of 167-219 K, associated with local motions, and T<sub>g,α</sub> in the range of 313-330 K associated with large-scale motions, for the microspheres examined. Using FTIR measurements in the mid-infrared we were able to characterise the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined T<sub>g,β</sub> and T<sub>g,α</sub> and free volume and microsphere dynamics. <br>

scholarly journals Terahertz Spectroscopy: An Investigation of the Structural Dynamics of Freeze-Dried Poly Lactic-co-glycolic Acid Microspheres

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 291 ◽  
Author(s):  
Talia A. Shmool ◽  
Philippa J. Hooper ◽  
Gabriele S. Kaminski Schierle ◽  
Christopher F. van der Walle ◽  
J. Axel Zeitler
Keyword(s):  
Freeze Drying ◽  
Large Scale ◽  
Glycolic Acid ◽  
Terahertz Spectroscopy ◽  
Double Emulsion ◽  
Plga Microspheres ◽  
Terahertz Time Domain Spectroscopy ◽  
Freeze Dried ◽  
Biodegradable Poly ◽  
Temperature Variable

Biodegradable poly lactic-co-glycolic acid (PLGA) microspheres can be used to encapsulate peptide and offer a promising drug-delivery vehicle. In this work we investigate the dynamics of PLGA microspheres prepared by freeze-drying and the molecular mobility at lower temperatures leading to the glass transition temperature, using temperature-variable terahertz time-domain spectroscopy (THz-TDS) experiments. The microspheres were prepared using a water-in-oil-in-water (w/o/w) double-emulsion technique and subsequent freeze-drying of the samples. Physical characterization was performed by morphology measurements, scanning electron microscopy, and helium pycnometry. The THz-TDS data show two distinct transition processes, T g , β in the range of 167–219 K, associated with local motions, and T g , α in the range of 313–330 K, associated with large-scale motions, for the microspheres examined. Using Fourier transform infrared spectroscopy measurements in the mid-infrared, we were able to characterize the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined T g , β and T g , α and free volume and microsphere dynamics.

scholarly journals PLGA Microspheres Incorporated Gelatin Scaffold: Microspheres Modulate Scaffold Properties

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Indranil Banerjee ◽  
Debasish Mishra ◽  
Tapas K. Maiti
Keyword(s):  
Mechanical Properties ◽  
Cell Proliferation ◽  
Cell Adhesion ◽  
Growth Kinetics ◽  
Freeze Drying ◽  
Biological Properties ◽  
Plga Microspheres ◽  
Polymer Scaffolds ◽  
Freeze Dried ◽  
Scaffold Properties

Freeze drying is one of the popular methods of fabrication for poly(lactide-co-glycolide) (PLGA) microspheres incorporated polymer scaffolds. However, the consequence of microspheres incorporation on physical and biological properties of scaffold has not been studied yet. In this study, attempt has been made to characterize the effect of PLGA microsphere incorporation on the physical properties of freeze-dried gelatin scaffold and its influence on cytocompatibility. Scaffolds loaded with varying amount of PLGA microspheres (10%, 1%, 0.1% w/w) were subjected to microarchitecture analysis, swelling, porosity, mechanical properties, biodegradation, cell adhesion, and cell proliferation studies. Results revealed that an increase in percentage loading of microspheres reduced the pore size and uniformity of the pore structure. Moreover, loading of PLGA microspheres up to 1% w/w significantly increased porosity, swelling, and mechanical properties of the scaffold but variations were not proportional for 10% w/w loading. Results also showed that PLGA microspheres have no significant effect on cell adhesion but influenced the growth kinetics.

scholarly journals Porous PLGA Microspheres Effectively Loaded with BSA Protein by Electrospraying Combined with Phase Separation in Liquid Nitrogen

2010 ◽  
Vol 6 ◽  
pp. 1-18 ◽  
Author(s):  
G. Liu ◽  
X. Miao ◽  
W. Fan ◽  
Ross Crawford ◽  
Yin Xiao
Keyword(s):  
Porous Structure ◽  
Liquid Nitrogen ◽  
Encapsulation Efficiency ◽  
Freeze Drying ◽  
Double Emulsion ◽  
Polymer Microspheres ◽  
Particle Sizes ◽  
Plga Microspheres ◽  
Loading Efficiency ◽  
Highly Porous

Polymer microspheres loaded with bioactive particles, biomolecules, proteins, and/or growth factors play important roles in tissue engineering, drug delivery, and cell therapy. The conventional double emulsion method and a new method of electrospraying into liquid nitrogen were used to prepare bovine serum albumin (BAS)-loaded poly(lactic-co-glycolic acid) (PLGA) porous microspheres. The particle size, the surface morphology and the internal porous structure of the microspheres were observed using scanning electron microscopy (SEM). The loading efficiency, the encapsulation efficiency, and the release profile of the BSA-loaded PLGA microspheres were measured and studied. It was shown that the microspheres from double emulsion had smaller particle sizes (3-50 m), a less porous structure, a poor loading efficiency (5.2 %), and a poor encapsulation efficiency (43.5%). However, the microspheres from the electrospraying into liquid nitrogen had larger particle sizes (400-600 m), a highly porous structure, a high loading efficiency (12.2%), and a high encapsulation efficiency (93.8%). Thus the combination of electrospraying with freezing in liquid nitrogen and subsequent freeze drying represented a suitable way to produce polymer microspheres for effective loading and sustained release of proteins.

scholarly journals Antibodies Processed Using High Dilution Technology Distantly Change Structural Properties of IFNγ Aqueous Solution

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1864
Author(s):  
Nikita Penkov
Keyword(s):  
Aqueous Solution ◽  
Structural Properties ◽  
Direct Contact ◽  
Large Scale ◽  
Terahertz Spectroscopy ◽  
Bound Water ◽  
Emission Spectra ◽  
Water Molecules ◽  
Terahertz Time Domain Spectroscopy ◽  
Weakly Bound

Terahertz spectroscopy allows for the analysis of vibrations corresponding to the large-scale structural movements and collective dynamics of hydrogen-bonded water molecules. Previously, differences had been detected in the emission spectra of interferon-gamma (IFNγ) solutions surrounded by extremely diluted solutions of either IFNγ or antibodies to IFNγ without direct contact compared to a control. Here we aimed to analyse the structural properties of water in a sample of an aqueous solution of IFNγ via terahertz time-domain spectroscopy (THz-TDS). Tubes with the IFNγ solution were immersed in fluidised lactose saturated with test samples (dilutions of antibodies to IFNγ or control) and incubated at 37 °C for 1, 1.5–2, 2.5–3, or 3.5–4 h. Fluidised lactose was chosen since it is an excipient in the manufacture of drugs based on diluted antibodies to IFNγ. After incubation, spectra were recorded within a wavenumber range of 10 to 110 cm−1 with a resolution of 4 cm−1. Lactose saturated with dilutions of antibodies to IFNγ (incubated for more than 2.5 h) changed the structural properties of an IFNγ aqueous solution without direct contact compared to the control. Terahertz spectra revealed stronger intermolecular hydrogen bonds and an increase in the relaxation time of free and weakly bound water molecules. The methodology developed on the basis of THz-TDS could potentially be applied to quality control of pharmaceuticals based on extremely diluted antibodies.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

Organic solvent-assisted free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 on 3D graphene as a high energy density cathode

2015 ◽  
Vol 51 (91) ◽  
pp. 16381-16384 ◽  
Author(s):  
Yuelong Xin ◽  
Liya Qi ◽  
Yiwei Zhang ◽  
Zicheng Zuo ◽  
Henghui Zhou ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Solvent ◽  
Freeze Drying ◽  
Large Scale ◽  
High Energy ◽  
High Energy Density ◽  
Free Standing ◽  
3D Graphene ◽  
Active Particles

A novel organic solvent-assisted freeze-drying pathway, which can effectively protect and uniformly distribute active particles, is developed to fabricate a free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 (LR)/rGO electrode on a large scale.

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