Microfluidic dehydration

Tanaka K, Motomatsu S, Koyama K et al (2007) Large-scale synthesis of immunoactivating natural product, pristane, by continuous microfluidic dehydration as the key step. Org Lett 9 299-302... 

Although it is not a gas-phase but a solution-phase reaction, Fukase and coworkers employed microflow systems for the acid-catalyzed dehydration of allylic alcohols to give dienes. The microfluidic dehydration effectively took place at 80 °C using p-TsOH as a catalyst and THF and toluene as solvents. Both an IMM standard micromixer and a PTFE (Teflon) Comet XOl reactor performed the dehydration successfully [6]. 

Entrapment of plasmid DNA and/or protein into liposomes entails the preparation of a lipid film from which multilamellar vesicles and, eventually, small unilamellar vesicles (SUVs) are produced. SUVs are then mixed with the plasmid DNA and/or protein destined for entrapment and dehydrated. The dry cake is subsequently broken up and rehydrated to generate multilamellar dehydration-rehydration vesicles (DRV) containing the plasmid DNA and/or protein. On centrifugation, liposome-entrapped vaccines are separated from nonentrapped materials. When required, the DRV are reduced in size by microfluidization in the presence or absence of nonentrapped materials or by employing an alternative method (7) of DRV production, which utilizes sucrose (see below). 

Quantitative entrapment of vaccines into small (up to about 200 nm diameter) liposomes in the absence of microfluidization (which can damage DNA and other labile materials when extensive) can be carried out by a novel one-step method (7) as follows SUVs (e.g., cationic) prepared as in section Preparation of Small Unilamellar Vesicles are mixed with sucrose to give a range of sucrose-to-lipid weight/weight ratio of 1.0 to 5.0 and the appropriate amount of plasmid DNA (e.g., 10-500 pg) and/or protein (e.g., up to 1 mg). The mixture is then rapidly frozen and subjected to dehydration by freeze-drying, followed by rehydration as in section Preparation of Vaccine-Containing Dehydration-Rehydration Vesicles. ... 

The content of vaccine within the small liposomes is estimated as in the section Estimation of Vaccine Entrapment in Dehydration-Rehydration Vesicles Liposomes for both microfluidized and sucrose liposomes and expressed as percentage of DNA and/or protein in the mixture subjected to freeze drying as in the section Preparation of Vaccine-Containing Small Liposomes by the Sucrose Method in the case of sucrose small liposomes or in the original DRV preparation (obtained in the section Estimation of Vaccine Entrapment in DRV Liposomes ) for microfluidized liposomes. Vesicle size measurements are carried out by PCS as described elsewhere (6,8,17). Liposomes can also be subjected to microelectrophoresis in a Zetasizer to determine their zeta potential. This is often required to determine the net surface charge of DNA-containing cationic liposomes. 

Elimination is one of the most important types of reactions for making carbon-carbon multiple bonds in organic synthesis. However, only a few examples of elimination reactions in microflow reactors have been reported. P-Hydroxyketones provide the corresponding dehydrated products, a,P-unsaturated ketones, in almost quantitative yields under the microfluidic conditions, whereas conventional macro batch reactors give lower yields of the products due to recovery of the starting materials and formation of other hydrophobic byproducts (Figure 5.3) [21]. 

Electrolytes like sodium, potassium, and chloride are important parameters in monitoring the health of critically ill patients (Kapoor et al., 2014). Sodium monitoring in sweat by means of a conductometric miCTofluidic sensor can indicate levels of dehydration (Liu et al., 2014). Multichannel capillary electrophoresis has been used to concurrently detect multiple cations and anions (Mai et al., 2016). Paper microfluidics using a salt bridge could potentially measure chloride ion concentraflon in blood serum (Jang et al., 2015). 

Liu, G., Smith, K., Kaya, T., 2014. Implementation of a microfluidic conductivity sensor—a potential sweat electrolyte sensing system for dehydration detection. In Presented at the 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), pp. 1678-1681. http //dx.doi.org/10.1109/EMBC.2014.6943929. 

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