Natural polymer-based drug carriers have been developed for antimicrobial applications but several problems remain with their poor controllability of drug loading and degradation. We introduce a novel method to produce improved antibiotic alginate fiber with high drug entrapment properties and a delayed degradation profile. A microfluidic spinning system with a low-polarity isopropyl alcohol (IPA) sheath flow was used to dehydrate an alginate/ampicillin aqueous solution and to form densely packed fiber with enhanced drug loading efficiency. The amounts of ampicillin initially loaded in the IPA-fiber were much higher than in the conventional water-based fiber and they released a more prolonged profile. The fibers were characterized by analyzing the morphology, mass loss and structural properties.The fibers were also used for an in vivo infected wound healing study. The results showed that the IPAbased fibrous alginate drug carrier possesses superior properties for loading drugs and potentials for wound healing applications with easy management.

Nanofibers have been applied to tissue engineering scaffolds because fiber diameters are of the same scale as the physical structure of protein fibrils in the native extracellular matrix. In this study, we utilized cell matrix engineering combined with cell sheet matrix and electrospinning technologies. We studied small-diameter vascular grafts in vitro by seeding smooth muscle cells onto electrospun poly(lactide-co-ɛ-caprolactone) (PLCL) scaffolds, culturing and constructing a three-dimensional network. The vascular grafts constructed using cell matrix engineering were similar to the native vessels in their mechanical properties, such as tensile strength, tensile strain, and e-modulus. Also, they had a self-sealing property more improved than GORE-TEX because PLCL has compatible elasticity. Small-diameter vascular grafts constructed using matrix engineering have the potential to be suitable for vascular grafts.

This paper provides a method for microscale fiber spinning and the in situ construction of a 3D fibrous scaffold on a single microfluidic platform. This platform was also used to fabricate a variety of fibrous scaffolds with diverse compositions without the use of complicated devices. We explored the potential utility of the fibrous scaffolds for tissue engineering applications by constructing a fibrous scaffold encapsulating primary hepatocytes. The cells in scaffold were cultured over seven days and maintained higher viability comparing with 3D alginate non-fibrous block. The main advantage of this platform is that the fibrous structure used to form a scaffold can be generated without damaging the mechanically weak alginate fibers or encapsulated cells because all procedures are performed in a single platform without the intervention of the operator. In addition, the proposed fibrous scaffold permitted high diffusion capability of molecules, which enabled better viability of encapsulated cells than non-fibrous scaffold even in massive cell culture.

Electrospun nanofibrous scaffolds have several advantages, such as an extremely high surface-to-volume ratio, tunable porosity, and malleability to conform over a wide variety of sizes and shapes. However, there are limitations to culturing the cells on the scaffold, including the inability of the cells to infiltrate because of the scaffold's nano-sized pores. To overcome the limitations, we developed a controlled pulsatile bioreactor that produces static and dynamic flow, which improves transfer of such nutrients and oxygen, and a tubular-shaped vascular graft using cell matrix engineering. Electrospun scaffolds were seeded with smooth muscle cells (SMCs), cultured under dynamic or static conditions for 14 days, and analyzed. Mechanical examination revealed higher burst strength in the vascular grafts cultured under dynamic conditions than under static conditions. Also, immunohistology stain for alpa smooth muscle actin showed the difference of SMC distribution and existence on the scaffold between the static and dynamic culture conditions. The higher proliferation rate of SMCs in dynamic culture rather than static culture could be explained by the design of the bioreactor which mimics the physical environment such as media flow and pressure through the lumen of the construct. This supports regulation of collagen and leads to a significant increase in tensile strength of the engineered tissues. These results showed that the SMCs/electrospinning poly (lactide-co-ε-caprolactone) scaffold constructs formed tubular-shaped vascular grafts and could be useful in vascular tissue engineering.