The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry eye disease and are accompanied by changes in the quality and quantity of tear film lipids. In dry eye, eye drops containing oil-in-water emulsions are used for the supplementation of lipids and surface-active components to the tear film. We explore in detail the biophysical aspects of interactions of specific surface-active compounds, cetalkonium chloride and poloxamer 188, which are present in oil-in-water emulsions, with tear lipids. The aim is to better understand the macroscopically observed eye drops-tear film interactions by rationalizing them at the molecular level. To this end, we employ a multi-scale approach combining experiments on human meibomian lipid extracts, measurements using synthetic lipid films, and in silico molecular dynamics simulations. By combining these methods, we demonstrate that the studied compounds specifically interact with the tear lipid film enhancing its structure, surfactant properties, and elasticity. The observed effects are cooperative and can be further modulated by material packing at the tear-air interface.
- MeSH
- film jako téma * MeSH
- fluorescenční mikroskopie metody MeSH
- kvartérní amoniové sloučeniny chemie MeSH
- lidé MeSH
- lipidy chemie MeSH
- mastné alkoholy chemie MeSH
- meibomské žlázky metabolismus MeSH
- poloxamer chemie MeSH
- simulace molekulární dynamiky * MeSH
- teoretické modely MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Protocells are objects that mimic one or several functions of biological cells and may be embodied as solid particles, lipid vesicles, or droplets. Our work is based on using decanol droplets in an aqueous solution of sodium decanoate in the presence of salt. A decanol droplet under such conditions bears many qualitative similarities with living cells, such as the ability to move chemotactically, divide and fuse, or change its shape. This article focuses on the description of a shape-changing process induced by the evaporation of water from the decanoate solution. Under these conditions, the droplets perform complex shape changes, whereby the originally round decanol droplets grow into branching patterns and mimic the growth of appendages in bacteria or axon growth of neuronal cells. We report two outcomes: (i) the morphological changes are reversible, and (ii) multiple protocells avoid contact between each other during the morphological transformation. The importance of these morphological changes in the context of artificial life are discussed.
Short-chain unsaturated aliphatic alcohols exist as volatile liquids, some of them are used in both industrial and non-industrial environments, and some of them are natural products of different organisms. These alcohols very often work as semiochemicals, including acting as pheromones, attractants, repellents, etc.. Long-chain poly-unsaturated alcohols are often toxic principals of certain plants, thereby presenting a risk to humans.
- MeSH
- mastné alkoholy farmakokinetika chemie škodlivé účinky MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- přehledy MeSH
The purpose of this experimental work was the development of hydrophilic-lipophilic matrix tablets for controlled release of slightly soluble drug represented here by diclofenac sodium (DS). Drug dissolution profile optimization provided by soluble filler was studied. Matrix tablets were based on cetyl alcohol as the lipophilic carrier, povidone as the gel-forming agent, and common soluble filler, that is lactose or sucrose of different particle size. Physical properties of tablets prepared by melt granulation and drug release in a phosphate buffer of pH 6.8 were evaluated. In vitro studies showed that used filler type, filler to povidone ratio and sucrose particle size influenced the drug release rate. DS dissolution profile could be changed within a wide range from about 50% per 24 hours to almost 100% in 10 hours. The release constant values confirmed that DS was released from matrices by the diffusion and anomalous transport. The influence of sucrose particle size on the drug release rate was observed. As the particle size decreased, the drug release increased significantly and its dissolution profile became more uniform. Soluble fillers participated in the pore-forming process according to their solubility and particle size. Formulations containing 100 mg of the drug, 80 mg of cetyl alcohol, 40 mg of povidone, and 80 mg of either lactose or sucrose (particle size 250-125 microm) were considered optimal for 24-hour lasting dissolution of DS.
- MeSH
- antiflogistika nesteroidní aplikace a dávkování chemie MeSH
- časové faktory MeSH
- diklofenak aplikace a dávkování chemie MeSH
- laktosa chemie MeSH
- léky s prodlouženým účinkem MeSH
- mastné alkoholy chemie MeSH
- nosiče léků chemie MeSH
- pomocné látky chemie MeSH
- povidon chemie MeSH
- rozpustnost MeSH
- sacharosa chemie MeSH
- tablety MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
