No abstract

4-Dibenzocyclooctynol (DIBO) was used as an initiator for the ring-opening copolymerization of ε-caprolactone and 1,4,8-trioxaspiro[4.6]-9-undecanone (TOSUO) resulting in a series of DIBO end-functionalized copolymers. Following deprotection of the ketone group, the polymers were derivatized with aminooxyl-containing compounds by oxime ligation. Mixtures of keto-and alkyne-derivatized polymers were co-electrospun into well-defined nanofibers containing three separate chemical handles. Strain-promoted azide alkyne cycloaddition (SPAAC), oxime ligation, and copper-catalyzed azide alkyne cycloaddition (CuAAC) were used to sequentially functionalize the nanofibers first with fluorescent reporters and then separately with bioactive Gly-Arg-Gly-Asp-Ser (GRGDS), BMP-2 peptide, and dopamine. This translationally relevant approach facilitates the straightforward derivatization of diverse bioactive molecules that can be controllably tethered to the surface of nanofibers. P olymeric nanofibers have been studied extensively for applications in wound healing and regenerative medicine. 1 Most polymers can be fabricated into nanofibers via melt or electrospinning with highly tunable size and morphology by manipulating various experimental parameters. 2 Nanofibers have been found to influence cell function in a number of ways including morphology, confinement via contact guidance, and mechanical properties. 3,4 While there have been several reports of methods for placing bioactive groups on nanofibers, 5−8 degradable polymers present some significant limitations with regard to conjugation chemistry. To preserve the structural and morphological integrity of the nanofibers, any conjugation method must be compatible with a solvent system orthogonal to the solubility parameters of the polymer. One strategy to overcome this limitation has been to introduce the bioactive species prior to electrospinning. 9,10 While some have successfully utilized this approach, it is inefficient in that a significant fraction of the bioactive species are buried in the nanofiber and, as such, are not bioavailable to the target cell population. The lack of control over surface functionality severely complicates any manufacturing process and regulatory strategy when trying to advance these materials to clinical applications.There have been several demonstrations of peptide-modified nanofibers in biomedicine including bone, 11 neural, 12−14 and vascular applications. 15,16 However, other than integrinmediated adhesion via Gly-Arg-Gly-Asp-Ser (GRGDS) peptides, there are no reports describing the use and utility of multiple (≥3) bioactive groups attached to nanofibers. However, in higher organisms, it is well established that multiple bioactive molecules work synergistically in time-and concentration-dependent manners to regulate any number of cellular functions. 17−19 In order to mimic these complex interactions, strategies for controllably derivatizing electrospun nanofibers are needed to advance our understanding of cellular behavior in vitro and in vivo...

Women's "failure to negotiate" is framed within the larger context of women's difficulties in advocating for themselves. These difficulties are examined in light of both the costs associated with female self-promotion and the often invisible link for women between being liked and being influential. Suggestions are made for minimizing the passive injustices that are often a consequence of women's self-advocacy dilemma.Consider the following situation. A man and a woman are hired as assistant professors at a large university. Although not in the same department, they are in the same college (i.e., social sciences) and have the same dean. They are outstanding in their respective fields, which no doubt accounts for their job offers in a tight academic job market. The man and woman have equivalent research records, letters of recommen dation, and teaching experience; in fact, they are essentially indistin guishable on paper. Yet, the man's starting salary is considerably higher than the woman's. A male administrator further up the bureaucratic hierarchy notices this discrepancy and discusses the ca"ses with the relevant department chairs and dean. He learns that the new assistant professors were offered the same starting salary. The woman accepted, but the man negotiated and consequently was paid more. This is a true account. The situation did not occur on our campus, but was related to us by someone who was impressed by the "enlightened" administrator who noticed the pay discrepancy. When we asked how this enlightened individual responded once he knew the reason for the

Degradable poly(ester urea)s (PEU)s were electrospun into nanofiber sheets and assessed for their potential to be used in soft tissue repair. The level of residual solvent was measured and the effects of ethylene oxide and electron beam sterilization techniques on molecular mass, mass distribution, and morphology were quantified. Two PEU compositions that formed stable nanofiber sheets were advanced into a pilot study in vitro and in vivo as candidate materials for hernia repair. Cell viability, spreading, proliferation, and migration were examined in vitro. Nanofiber sheets were implanted subcutaneously into mice and analyzed via microangiography and histology for tissue incorporation. Nanofiber sheets performed similarly to decellularized extracellular matrix (ECM) in vitro, but the lack of sufficient pore structure inhibited cellular infiltration after 14 days of culture. The lack of microporous features in nanofiber sheets also contributed to low levels of cellular infiltration, angiogenesis, and matrix deposition in vivo. A preliminary study to increase pore size in nanofibers was performed using coaxial electrospinning resulting in significant improvement in tissue infiltration in vivo.

The synthesis and characterization of iodine-functionalized phenylalanine-based poly(ester urea)s (PEUs) are reported. 4-Iodo-L-phenylalanine and L-phenylalanine were separately reacted with 1,6-hexanediol to produce two monomers, bis-4-I-L-phenylalanine-1,6-hexanediol-diester (1-IPHE-6 monomer) and bis-L-phenylalanine-1,6-hexanediol-diester (1-PHE-6 monomer). By varying the feed ratio of the 1-IPHE-6 and 1-PHE-6 monomers, the copolymer composition was modulated resulting in a wide variation in thermal, mechanical and radiopacity properties. Microcomputed tomography (μ-CT) projections demonstrate that increasing iodine content results in greater X-ray contrast. Compression tests of dry and wet porous scaffolds indicate that the poly(1-IPHE-6)0.24-co-poly(1-PHE-6)0.76 material results in the highest compression modulus. MC3T3 cell viability and spreading studies show PEUs are nontoxic to cells. As most medical device procedures require placement verification via fluoroscopic imaging, materials that possess inherent X-ray contrast are valuable for a number of applications.