Non-Arrhenius Kinetics and Slowed-Diffusion Mechanism of Molecular Aggregation of a Rhodamine Dye on Colloidal Particles

The aim of the study was to develop a novel buccal dosage form to transport rhodamine 123 and human insulin as models for poorly water-soluble and biological drugs, using lipid-core micelles (LCMs)-loaded mucoadhesive films. LCMs were synthesized by a low-energy hot emulsification process, yielding spherically shaped, small-sized, monodispersed and negatively charged carriers with high entrapment efficiency. In vitro release studies demonstrated a higher release of insulin rather than rhodamine from LCMs in simulated physiological conditions, due to an initial burst release effect; however, both release profiles are mainly explained by a diffusion mechanism. Furthermore, LCMs-loaded mucoadhesive films were manufactured and preserved with similar mechanical properties and optimal mucoadhesive behavior compared to nonloaded films. Ex vivo permeation experiments using excised porcine buccal epithelium reveal that both rhodamine and insulin-loaded LCM films elicited a significantly enhanced permeation effect compared to LCMs in suspension and free drugs in solution as controls. Hence, LCMs-loaded mucoadhesive films are suitable as buccal dosage form for the transport and delivery of rhodamine 123 and insulin, as models for poorly water-soluble and biological drugs, respectively.

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Microscale diffusiophoresis of proteins

10.21203/rs.3.rs-90645/v1 ◽

2020 ◽

Author(s):

Quentin Peter ◽

Raphaël Jacquat ◽

Therese Herling ◽

Pavan Challa ◽

Tadas Kartanas ◽

...

Keyword(s):

Colloidal Particles ◽

Chemical Potential ◽

Living Systems ◽

Spatial Organisation ◽

Spatial Gradients ◽

Molecular Scale ◽

A Cell ◽

Transport Effects ◽

Biological Functionality

Abstract Living systems are characterised by their spatially highly inhomogeneous nature which is susceptible to modify fundamentally the behaviour of biomolecular species, including the proteins that underpin biological functionality in cells. Spatial gradients in chemical potential are known to lead to strong transport effects for colloidal particles, but their effect on molecular scale species such as proteins has remained largely unexplored. Here we demonstrate with microfluidic measurements that individual proteins can undergo strong diffusiophoretic motion in salt gradients in a manner which is sufficient to overcome diffusion and lead to dramatic changes in their spatial organisation on the scale of a cell. Moreover, we demonstrate that this phenomenon can be used to control the motion of proteins in microfluidics devices. These results open up a path towards a physical understanding of the role of gradients in living systems in the spatial organisation of macromolecules and highlight novel routes towards protein sorting applications on device.

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Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

International Astronomical Union Colloquium ◽

10.1017/s0252921100014950 ◽

1997 ◽

Vol 161 ◽

pp. 437-442

Author(s):

Salvatore Di Bernardo ◽

Romana Fato ◽

Giorgio Lenaz

Keyword(s):

Experimental Evidence ◽

Lipid Membranes ◽

Energy Supply ◽

Redox Reactions ◽

Living Systems ◽

Asymmetric Distribution ◽

Conservation Of Energy ◽

Asymmetrical Distribution ◽

Energy Conserving ◽

Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

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Direct observations of radiation-enhanced transformations in glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075543 ◽

1983 ◽

Vol 41 ◽

pp. 354-355

Author(s):

J. F. DeNatale ◽

D. G. Howitt

Keyword(s):

Glass Matrix ◽

Diffusion Mechanism ◽

Bubble Formation ◽

Silicate Glasses ◽

Phase Decomposition ◽

Direct Observations ◽

Thin Foils ◽

Oxygen Bubble ◽

Electron Energy Loss ◽

Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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Prolonged Fixation Studies For Spaceflight

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072101 ◽

1973 ◽

Vol 31 ◽

pp. 332-333

Author(s):

Robert Corbett ◽

Delbert E. Philpott ◽

Sam Black

Keyword(s):

High Pressure ◽

Living Systems ◽

Prolonged Storage ◽

Time Intervals ◽

Early Signs ◽

Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

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Ultrastructure of Lymphatic Capillaries in the Transport of Colloidal Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060945 ◽

1967 ◽

Vol 25 ◽

pp. 186-187

Author(s):

L. V. Leak ◽

J. F. Burke

Keyword(s):

Connective Tissue ◽

Colloidal Particles ◽

Ultrastructural Level ◽

Vital Role ◽

Time Intervals ◽

Thorium Dioxide ◽

Lymphatic Capillary ◽

Tissue Area ◽

Rapid Removal ◽

Tissue Fluids

The vital role played by the lymphatic capillaries in the transfer of tissue fluids and particulate materials from the connective tissue area can be demonstrated by the rapid removal of injected vital dyes into the tissue areas. In order to ascertain the mechanisms involved in the transfer of substances from the connective tissue area at the ultrastructural level, we have injected colloidal particles of varying sizes which range from 80 A up to 900-mμ. These colloidal particles (colloidal ferritin 80-100A, thorium dioxide 100-200 A, biological carbon 200-300 and latex spheres 900-mμ) are injected directly into the interstitial spaces of the connective tissue with glass micro-needles mounted in a modified Chambers micromanipulator. The progress of the particles from the interstitial space into the lymphatic capillary lumen is followed by observing tissues from animals (skin of the guinea pig ear) that were injected at various time intervals ranging from 5 minutes up to 6 months.

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Deposited emulsion particles in the pores of aluminum oxide film

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109392 ◽

1978 ◽

Vol 36 (1) ◽

pp. 450-451

Author(s):

Michio Ashida ◽

Yasukiyo Ueda

Keyword(s):

Oxide Film ◽

Acid Solution ◽

Barrier Layer ◽

Colloidal Particles ◽

Oxalic Acid Solution ◽

Anodic Oxide ◽

Anodic Oxide Film ◽

Carbon Replica ◽

Sectioning Method ◽

Thin Sectioning

An anodic oxide film is formed on aluminum in an acidic elecrolyte during anodizing. The structure of the oxide film was observed directly by carbon replica method(l) and ultra-thin sectioning method(2). The oxide film consists of barrier layer and porous layer constructed with fine hexagonal cellular structure. The diameter of micro pores and the thickness of barrier layer depend on the applying voltage and electrolyte. Because the dimension of the pore corresponds to that of colloidal particles, many metals deposit in the pores. When the oxide film is treated as anode in emulsion of polyelectrolyte, the emulsion particles migrate onto the film and deposit on it. We investigated the behavior of the emulsion particles during electrodeposition.Aluminum foils (99.3%) were anodized in either 0.25M oxalic acid solution at 30°C or 3M sulfuric acid solution at 20°C. After washing with distilled water, the oxide films used as anode were coated with emulsion particles by applying voltage of 200V and then they were cured at 190°C for 30 minutes.

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