Fabrication of monodisperse liposomes-in-microgel hybrid microparticles in capillary-based microfluidic devices.

This study introduces a drop-based microfluidic approach to physically immobilize liposomes in microgel (liposomes-in-microgel) particles. For this, we generate a uniform liposomes-in-water-in-oil emulsion in a capillary-based microfluidic device. Basically, we have investigated how the flow rate and flow composition affect generation of emulsion precursor drops in micro-channels. Then, the precursor emulsion drops are solidified by photo-polymerization. From characterization of hydrogel mesh sizes, we have figured out that the mesh size of the liposomes-in-microgel particles is bigger than that of bare microgel particles, since liposomes take space in the hydrogel phase. In our further study on drug releasing, we have observed that immobilization of liposomes in the microgel particles can not only remarkably retard drug releasing, but also enables a sustained release, which stems from the enhanced matrix viscosity of the surrounding hydrogel phase.

Nanoemulsification of pseudo-ceramide by molecular association with mannosylerythritol lipid.

Ceramide molecules in water-based solutions readily attract each other to form molecular crystals, which seriously hampers to diversify their formulations. This paper describes a facile method that allows fabrication of stable ceramide emulsions through an effective molecular association with a lipid having an asymmetric molecular geometry. The lipid considered in this study is mannosylerythritol lipid (MEL). MEL is specialized in having a unique molecular structure containing sugar alcohol erythritol as a hydrophilic part and two alkyl chains with different number of carbons as hydrophobic moieties. Our particular interest has been focused on experimentally demonstrating how MEL interacts with pseudo-ceramide molecules by observing phase properties, emulsion morphology, and suspension stability. The pseudo-ceramide emulsions prepared with MEL show remarkably improved dispersion stability without either formation of molecular crystals or changes in particle sizes even after storing them for a long time. This suggests that MEL readily associates with the pseudo-ceramide due to the hydrophobic interaction, while it makes a break in the continuity of the molecular assembly of the pseudo-ceramide molecules themselves due to the geometric hindrance coming from MEL's asymmetric molecular structure.

Immobilization of a mediator onto carbon cloth electrode and employment of the modified electrode to an electroenzymatic bioreactor.

5,5'-Dithiobis(2-nitrobenzoic acid) (DTNB) was selected as an electron transfer mediator and was covalently immobilized onto high porosity carbon cloth to employ as a working electrode in an electrochemical NAD(+)-regeneration process, which was coupled to an enzymatic reaction. The voltammetric behavior of DTNB attached to carbon cloth resembled that of DTNB in buffered aqueous solution, and the electrocatalytic anodic current grew continuously upon addition of NADH at different concentrations, indicating that DTNB is immobilized to carbon cloth effectively and the immobilized DTNB is active as a soluble one. The bioelectrocatalytic NAD+ regeneration was coupled to the conversion of L-glutamate into alpha-ketoglutarate by L-glutamate dehydrogenase within the same microreactor. The conversion at 3 mM monosodium glutamate was very rapid, up to 12 h, to result in 90%, and then slow up to 24 h, showing 94%, followed by slight decrease. Low conversion was shown when substrate concentration exceeding 4 mM was tested, suggesting that L-glutamate dehydrogenase is inhibited by alpha-ketoglutarate. However, our electrochemical NAD+ regeneration procedure looks advantageous over the enzymatic procedure using NADH oxidase, from the viewpoint of reaction time to completion.

A case of variant angina developing transient collateral circulation during vasospasm.

Variant angina is characterized by spontaneous episodes of angina, usually occurring in the morning and having ST segment elevation on the electrocardiogram. However, in the case presented here, vasospasm and angina was shown by ergonovine without ST elevation. The patient was a 60-year-old man who presented with a 2-year history of frequent chest pain. There were no abnormalities in coronary angiography. When ergonovine (100 µg) was injected, total occlusion of the proximal right coronary artery was seen, without ST elevation at the electrocardiogram. The cause was collateral from left anterior descending artery to distal right coronary artery at the left coronary angiography. Therefore, in a patient with variant angina without ST elevation, a transient collateral circulation during vasospasm should be considered.