Many investigations of wound dressings equipped with drug delivery systems have recently been conducted. Chitosan is widely used not only as a material for wound dressing by the efficacy of its own, but also as a nanoparticle for drug delivery. In this study, an electrospun polycaprolactone nanofiber composite with chitosan nanoparticles (ChiNP-PCLNF) was fabricated and then evaluated for its drug release and biocompatibility to skin fibroblasts. ChiNP-PCLNF complexes showed no cytotoxicity and nanoparticles adsorbed by van der Waals force were released into aquatic environments and then penetrated into rat primary fibroblasts. Our studies demonstrate the potential for application of ChiNP-PCLNF as a wound dressing system with drug delivery for skin wound healing without side effects.

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.

Cellular membrane distortion invokes variations in cellular physiology. However, lack of an appropriate system to control the stress and facilitate molecular analyses has hampered progress of relevant studies. In this study, a microfluidic system that finely manipulates membrane distortion of Chlamydomonas reinhardtii (C. reinhardtii) was developed. The device facilitated a first-time demonstration that directs membrane distortion invokes variations in deflagellation, cell cycle, and lipid metabolism. C. reinhardtii showed a prolonged G1 phase with an extended total cell cycle time, and upregulated Mat3 regulated a cell size and cell cycle. Additionally, increased TAG compensated for the loss of cell mass. Overall, this study suggest that cell biology that requires direct membrane distortion can be realized using this system, and the implication of cell cycle with Mat3 expression of C. reinhardtii was first demonstrated. Finally, membrane distortion can be an attractive inducer for biodiesel production since it is reliable and robust.

Astrocytes are involved in neuron protection following central nervous system (CNS) injury; accordingly, engineered astrocytes have been investigated for their usefulness in cell therapy for CNS injury. Nanofibers have attracted a great deal of attention in neural tissue engineering, but their mechanical properties greatly influence physiology. Cellulose acetate (CA) has been studied for use in scaffolds owing to its biocompatibility, biodegradability, and good thermal stability. In this study, stiffness of CA nanofibers controlled by heat treatment was shown to regulate astrocyte activity. Adhesion and viability increased in culture as substrate became stiffer but showed saturation at greater than 2 MPa of tensile strength. Astrocytes became more active in terms of increasing intermediate filament glial fibrillary acidic protein (GFAP). The results of this study demonstrate the effects of stiffness alone on cellular behaviors in a three-dimensional culture and highlight the efficacy of heat-treated CA for astrocyte culture in that the simple treatment enables control of astrocyte activity.

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