A new scheme for the synthesis of phenylacetylene dendritic macromolecules is described which greatly facilitates the large-scale production of high molecular weight monodendrons. Simply by inverting the monomer protecting group scheme from B2AP to A2BP (where A = ArC=CH; B = Arl; Ap and Bp are protected versions of these groups), we show that the repetitive synthesis can be propagated through at least one higher generation on reaction scales 2 orders of magnitude greater than previously possible. Using this new scheme, we have prepared gram quantities of phenylacetylene monodendrons through generation four (I-Mbs-U-BuJm), in high yields. Possible reasons for the improvements are discussed. We furthermore show that the new route is amenable to a solid-phase convergent dendrimer synthesis which involves tethering the focal point monomer to an insoluble support. Preparation of phenylacetylene monodendrons by the solid-phase method is demonstrated through generation four, yielding monodendron products identical to those synthesized by solution methods. However, at generation four, coupling reactions using polymer supports can only be driven to completion with light loading of the focal point monomer.The solid-phase convergent method offers several advantages, especially in the synthesis of early generation monodendrons. \

The design and test of a multilaminate sheet developed for a hernia repair application is presented. As biomaterial applications become more complex, characterization of uniaxial properties becomes insufficient and biaxial testing becomes necessary. A measure of the in-plane biaxial strength of the device is inferred from a ball burst test. The results of this test for different thicknesses of the device are correlated with the uniaxial strength of the material. A biaxial test such as the ball burst test is more indicative of the properties of a planar material than would be a uniaxial test. The interactions in the biaxial mode of failure are of value and can be related back to a classical uniaxial tensile test from the ball burst test. The material used in this study to fabricate the device was a resorbable biomaterial called small intestinal submucosa (SIS). The effects of rehydration on the stiffness and associated ball burst properties of the SIS device were also measured. It is shown that at a rehydration time of 5 min from a reference dry state, steady-state mechanical properties are reached.

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.

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