Polymeric biomaterials have extensively been used in medicinal applications. However, factors that determine their biocompatibility are still not very clear. This article reviews various effects of the chemical structure and the surface properties of polymeric biomaterials on their biocompatibility, including protein adsorption, cell adhesion, cytotoxicity, blood compatibility, and tissue compatibility. Understanding these aspects of biocompatibility is important to the improvement of the biocompatibility of existing polymers and the design of new biocompatible polymers.

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Previous studies have shown that 4-benzyl-1-cyclopropyl-1,2,3,6-tetrahydropyridine is an excellent monoamine oxidase B (MAO-B) substrate (kappa cat/KM = 1538 min-1 mM-1) although the corresponding 4-phenyl analog displays MAO-B inactivating properties only. This behavior led us to speculate that the pathway for the MAO-B catalyzed oxidation of these tetrahydropyridines may not necessarily proceed via an initial single electron transfer step as proposed by others but rather through an initial alpha-carbon hydrogen atom abstraction step. In the present studies we have examined the interactions of various 4-phenoxy-, 4-phenyl-, and 4-thiophenoxy-1-cyclopropyl-1,2,3,6-tetrahydropyridine derivatives, some of which bear substituents on the phenyl ring. The 4-thiophenoxy- and all of the 4-phenoxytetrahydropyridine derivatives proved to be substrates but not inactivators of MAO-B, while several of the 4-phenyltetrahydropyridine derivatives were inactivators but not substrates. A case of particular interest was 1-cyclopropyl-4-(2-methylphenyl)-1,2,3,6-tetrahydropyridine, which displayed only substrate properties. The results are discussed in terms of two catalytic pathways, one of which involves partitioning of the proposed cyclopropylaminyl radical cation intermediate between cyclopropyl ring opening and proton loss while the second involves partitioning of the parent amine between an initial single electron transfer step, leading to cyclopropylaminyl radical cation formation and enzyme inactivation, and an initial alpha-carbon hydrogen atom abstraction step, leading to an allylic radical and dihydropyridinium product formation.

Fabrication of organic thin films by spontaneous molecular assembly is a powerful tool for creating carefully controlled supramolecular structures for nonlinear optical (NLO) applications. Recently, Decher and co-workers extended the work of Iler et al. to a new method of depositing thin films by layer-by-layer adsorption of linear polyions. [1,2] This ionic self-assembled monolayer (ISAM) technique provides significant advantages over other thin-film fabrication methods, including long-term stability, ease of fabrication, and greater film thickness. We have fabricated NLO films hundreds of bilayers thick with consistent, reproducible film growth with each bilayer.The observation of NLO behavior in polymer/organic dye ISAM thin films using commercially available dye molecules, specifically Poly S-119 (from Sigma), has already been reported. [3,4] The polar ordering of molecules that occurs due to the inherent nature of the ISAM process suggests that a number of similar NLO thin films may be synthesized using both other standard chromophore dyes and molecules specifically designed to yield an enhanced macro-scale net dipole moment. Consequently, we have designed and synthesized several new NLO polymers, including poly(methacrylic acids) and polyesters (Fig. 1), and fabricated non-centrosymmetric thin films using the ISAM process. In this paper, we present results that demonstrate the second-order NLO behavior of these polydye materials.Multilayer thin films of designed and synthesized polydye 1, polydye 2, and polydye 4 were self-assembled on glass substrates with polydiallyldimethylammonium chloride (PDDA) as the passive polycation layer. Uniform polydye films with up to 88 bilayers have already been fabricated, with an average bilayer thickness of the order of 2 nm, based on ellipsometry data. We have previously described in detail the process of synthesis of more than 1000 ISAM layers with good surface morphology, [5±7] resulting in films micrometers thick.UV-vis spectroscopy was used to identify the absorption and transmission characteristics of the NLO thin films as well as to quantify the growth of the multilayer structures. For example, optical absorbance spectra measured during the growth of two PDDA/polydye films on modified glass substrates are shown in Figures 2 and 3. The absorbance peaks of polydye 2 and polydye 4 are located at 435 and 365 nm, respectively, and exhibit a linear increase with the addition of each bilayer. This demonstrates that each bilayer contributes an equal amount of material to the thinfilm growth. In addition, the maximum differences between data collected at different locations across each film are at most a few percent, indicating excellent uniformity of the films. The ISAM method therefore produces thin films that are homogeneous through the film thickness as well as across the width and length of the film.Thin-film emission characteristics have important implications for optical and optoelectronic devices. As examples, the fluorescence spectra of polydye 2 and polydye 4 ISA...