Hong-Ru Lin

The mimicking and fabrication of gecko toe pads structures can lead to limitless applications. In this study, polypropylene (PP), polyethylene (PE) and polycaprolactone (PCL) nano‐fibers are fabricated using a porous membrane as template. The surface characteristics and physical properties of the samples yield different geometries, which determine the wetting and adhesive properties of the fabricated samples. Oriented and wave‐like shapes fibers present the Gecko effect, thanks to their ability to comply and hydrophobic asperities that uphold the water droplet when the wetting properties were tested. The samples are also found to be self‐cleaning due to their high contact angles and low contact angle hysteresis. Adhesion tests results prove that the samples are high reversible adhesion with the ability to stick to smooth surface in a dry and underwater environment. The adhesion on the samples can be enhanced with a double fibril layer or buckling property. They adhere better when the surface is not hydrophilic. By behaving in similar way as the real geckos, the results of this study show that the fabricated samples effectively present the Gecko effect. POLYM. ENG. SCI., 57:283–290, 2017. © 2016 Society of Plastics Engineers

In this study, polyurethane (PU)/hydrogel composites were fabricated for wound healing applications. The hydrogel is a copolymer of thermosensitive N-isopropyl acrylamide (NIPAAm) and acrylic acid (AAc). γ-ray irradiation was employed to simultaneously copolymerize NIPAAm with AAc and graft the hydrogel onto porous PU. Fibroblast growth factor-2 (FGF-2) was incorporated into the composite to facilitate wound healing. The physical properties of the composites were characterized, the in vitro release of FGF-2 was examined, and in vivo tests were conducted. The results indicate that the thermosensitive hydrogel can absorb most of the wound exudates due to its high water uptake ability. Due to its thermosensitive properties, the PU/hydrogel composite is easier to strip off than that of commercial wound dressing, which prevents additional injury to the wound when replacing the wound dressing. In vivo results show that the PU/hydrogel composite incorporating FGF-2 could accelerate wound healing and reduce scar formation.

Most hydrogels derived from either natural or synthetic sources suffer from the lack of mechanical strength. In this study, high strength poly(acrylic acid)–chitosan–silica (PAA–Ch–Si) hydrogels were prepared by UV polymerization for tissue engineering applications. Compressive strength up to 42 MPa can be achieved by the formation of an interpenetrating network (IPN) structure between PAA and chitosan with nano-silica as the filler. The preliminary cell culture of osteoblast cells (7F2) on PAA–Ch–Si hydrogels indicates good biological safety. The growth factor (platelet glue) is fast and completely released from PAA–Ch–Si hydrogel scaffolds within 620 min. The scaffold starts to degrade after eight months in vitro. Histological examinations demonstrate that the hydrogel incorporated with growth factors and osteoblast cells can promote cell migration. All these results illustrate that PAA–Ch–Si hydrogels are beneficial for tissue engineering applications and can be used as scaffolds for bone defect repair.

Chitosan-alginate hydrogel beads with hollow structure were successfully prepared by dropping method for controlling delivery of bitter gourd (BG). Loading efficiency and loading content of the beads are 97.8% and 86.4%, respectively. Swelling accompanied with degradation behavior suggests the beads have pH-sensitive characteristics. In vitro release study reveals that the release behavior of these beads is environmental oriented. The MTS test demonstrates the hydrogel beads have good cytocompatibility and do not compromise cell viability. Finally, in vivo study confirms that hollow hydrogel beads have controlled and sustained release capability.

Pluronic micelles were prepared for ophthalmic delivery by incorporation of ethyl acetate as a dispersion agent and their surfaces were modified by chitosan to improve their bioavailability. The micelles disperse well in the solution and have a core‐shell like structure with a particle size ranging from 93 to 181 nm for drug unloaded, 123–232 nm for drug‐loaded, and a zeta potential between 6.1 and 9.2 mV, indicating very suitable use as ophthalmic carrier. The in vitro serum stability tests indicate the particle size of the micelles was very stable during the serum absorption. The turbidity test reveals that the prepared micelles were very stable under phosphate buffered saline environment, which can prevent the blurred vision. The loading efficiency of metipranolol in micelles can be as high as 83%. Finally, the in vitro and in vivo studies indicate the pluronic micelles modified by chitosan have sustained release behavior and good pharmacological response. As the results, the pluroic‐chitosan micelles system provides a potential opportunity in decreasing frequency of administration and improving patient compliance for ocular drug delivery. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.