Atopic dermatitis (AD) is a complex skin disease primarily characterized by psoriasis of the stratum corneum. AD drugs have usually been used in acidic and hydrophilic solvents to supply moisture and prevent lipid defects. Ceramide is a typical treatment agent to regenerate the stratum corneum and relieve symptoms of AD. However, ceramide has limitation on direct use for skin because of its low dispersion properties in hydrophilic phase and side effects at excessive treatment. In this study, ceramide imbedded PLGA nanoparticles were developed with chitosan coating (Chi-PLGA/Cer) to overcome this problem. The chitosan coating enhanced initial adherence to the skin and prevented the initial burst of ceramide, but was degraded by the weakly acidic nature of skin, resulting in controlled release of ceramide with additional driving force of the squeezed PLGA nanoparticles. Additionally, the coating kinetics of chitosan were controlled by manipulating the reaction conditions and then mathematically modeled. The Chi-PLGA/Cer was not found to be cytotoxic and ceramide release was controlled by pH, temperature, and chitosan coating. Finally, Chi-PLGA/Cer was demonstrated to be effective at stratum corneum regeneration in a rat AD model. Overall, the results presented herein indicated that Chi-PLGA/Cer is a novel nanodrug for treatment of AD.
Four physical properties (solubility, vapor pressure, density, and
viscosity) of water + lithium bromide
+ lithium nitrate + 1,3-propanediol (LiBr/LiNO3 mole
ratio = 4, (LiBr +
LiNO3)/HO(CH2)3OH mass
ratio
= 3.5) were measured. The system, a possible working fluid for
an absorption heat pump, mainly consists
of absorbent (LiBr + LiNO3 +
HO(CH2)3OH) and refrigerant
(H2O). Solubilities were measured by the
visual polythermal method in the temperature range (285.55 to 346.65) K
and in the absorbent
concentration range (68.0 to 75.0) mass %. Vapor pressures were
measured by the boiling point method
in the temperature range (325.35 to 395.15) K and in the absorbent
concentration range (46.0 to 69.6)
mass %. Densities and viscosities were measured by a set of
hydrometers and viscometers, respectively,
in the temperature range (283.15 to 343.15) K and in the absorbent
concentration range (24.3 to 70.3)
mass %. The measured values were correlated.
Heat capacities of the water + lithium bromide + ethanolamine (LiBr/H 2 N(CH 2 ) 2 OH mass ratio ) 3.5) and water + lithium bromide + 1,3-propanediol (LiBr/HO(CH 2 ) 3 OH mass ratio ) 3.5) systems were measured by using an isoperibol solution calorimeter at four temperatures (283.15, 298.15, 313.15, and 333.15 K) and absorbent (LiBr + H 2 N(CH 2 ) 2 OH and LiBr + HO(CH 2 ) 3 OH) concentration ranges of (29.2 to 70.7)% and (30.7 to 68.3)%, respectively. The measured values were fitted with a simple equation by a least-squares method and the average absolute deviations between experimental and calculated values were 0.21% for the water + lithium bromide + ethanolamine system and 0.15% for the water + lithium bromide + 1,3-propanediol system, respectively.
Harvesting of microalgae is a cost-consuming step for biodiesel production. Cellulose has recently been studied as a biocompatible and inexpensive flocculant for harvesting microalgae via surface modifications such as cation-modifications. In this study, we demonstrated that cellulose nanofibrils (CNF) played a role as a microalgal flocculant via its network geometry without cation modification. Sulfur acid-treated tunicate CNF flocculated microalgae, but cellulose nanocrystals (CNC) did not. In addition, desulfurization did not significantly influence the flocculation efficiency of CNF. This mechanism is likely related to encapsulation of microalgae by nanofibrous structure formation, which is derived from nanofibrils entanglement and intra-hydrogen bonding. Moreover, flocculated microalgae were subject to mechanical stress resulting in changes in metabolism induced by calcium ion influx, leading to upregulated lipid synthesis. CNF do not require surface modifications such as cation modified CNC and flocculation is derived from network geometry related to nanocellulose size; accordingly, CNF is one of the least expensive cellulose-based flocculants ever identified. If this flocculant is applied to the biodiesel process, it could decrease the cost of harvest, which is one of the most expensive steps, while increasing lipid production.
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