Nanofiber assembly by rotary jet-spinning.

High-voltage electrical fields and low production rate limit electrospinning, the electrical charging of polymer liquids, as a means of nanofiber fabrication. Here, we show a facile method of fabrication of aligned three-dimensional nanofiber structures by utilizing high-speed, rotating polymer solution jets to extrude fibers. Termed rotary jet-spinning, fiber morphology, diameter, and web porosity can be controlled by varying nozzle geometry, rotation speed, and polymer solution properties. We demonstrate the utility of this technique for tissue engineering by building anisotropic arrays of biodegradable polymer fibers and seeding the constructs with neonatal rat ventricular cardiomyocytes. The myocytes used the aligned fibers to orient their contractile cytoskeleton and to self-organize into a beating, multicellular tissue that mimics the laminar, anisotropic architecture of the heart muscle. This technique may prove advantageous for building uniaxially aligned nanofiber structures for polymers which are not amenable to fabrication by electrospinning.

Durable and rechargeable biocidal polypropylene polymers and fibers prepared by using reactive extrusion.

Incorporation of N-halamine precursor onto polypropylene was explored by using a reactive extrusion process. Several cyclic and acyclic halamine precursors were grafted onto polypropylene backbone through a melt free radical graft copolymerization. The structures and morphology of the grafted polymer were characterized with FTIR, and scanning electron microscope. Thermal properties of the polymers were evaluated by differential scanning calorimetry. The halogenated products of the corresponding grafted samples exhibited potent antimicrobial properties against Escherichia coli, and the antimicrobial properties were durable and regenerable. The relationship between effective surface contact and biocidal efficacy are further discussed.