Biocompatibility-structure relationships

In order to identify tyrosine derivatives that would lead to polymers that are processible, mechanically strong, and also biocompatible, we initiated a detailed investigation of the structure-property relationships in polyiminocarbonates and polycarbonates. Since the amino and carboxylic acid groups of tyrosine dipeptide (the N and C termini) provide convenient attachment points, selected pendent chains can be used to modify the overall properties of the polymers. This is an important structural feature of tyrosine dipcptide derived polymers. 

The general approach of graded radiation exposure can also be used to examine light driven processes such as photopolymerization [19]. For example, Lin-Gibson and coworkers used this library technique to examine structure-property relationships in photopolymerized dimethacrylate networks [38] and to screen the mechanical and biocompatibility performance of photopolymerized dental resins [39]. In another set of recent studies, Johnson and coworkers combined graded light exposure with temperature and composition gradients to map and model the photopolymerization kinetics of acrylates, thiolenes and a series of co-monomer systems [40 2]. 

Malik, N., et al. 2000. Dendrimers Relationship between structure and biocompatibility in vitro, and preliminary studies on the biodistribution of 1251-labelled polyamidoamine dendrimers in vivo. 

Roberts, J.C. Bhalgat, M.K. Zera, R.T. Preliminary biological evaluation of polyamidoamine (PAMAM) star-burst dendrimers. J. Biomed. Mater. Res. 1996, 30, 53-65. Malik, N. Wiwattanapatapee, R. Klopsch, R. Lorenz, K. Frey, H. Weener, J.W. Meijer, E.W. Paulus, W. Duncan, R. Dendrimers relationship between structure and biocompatibility in vitro, and preliminary studies on the biodistribution of l-Labeled polyamidoamine dendrimers in vivo. J. Control. Release 2000, 65, 133-148. 

The direct electrochemistry of redox proteins has developed significantly in the past few years. Conditions now exist that permit the electrochemistry of all the proteins to be expressed at a range of electrodes, and important information about thermodynamic and kinetic properties of these proteins can be obtained. More recently, direct electron transfer between redox enzymes and electrodes has been achieved due to the more careful control of electrode surfaces. The need for biocompatible surfaces in bioelectrochemistry has stimulated the development of electrode surface engineering techniques, and protein electrochemistry has been reported at conducting polymer electrodes 82) and in membranes 83, 84). Furthermore, combination of direct protein electrochemistry with spectroscopic methods may offer 85) a novel way of investigating structure-function relationships in electron transport proteins. 

In this chapter, we first discuss the chemical and physical properties of chitosan, including the synthesis, modification, molecular structure, characterization, and structure-property relationship. Second, we review the topics of biocompatibility, biodegradability, and antimicrobial activity of chitosan. These properties make chitosan a potential biomaterial for many biomedical applications. 

Abstract In this contribution we review our recent progress in studies that aim at the understanding of the relationship between structure and surface reactivity of organic thin films on the one hand, and at the micro- and nanofabrication of bioreactive or biocompatible platforms on the other hand. Self-assembled monolayers (SAMs) of... 

Our target is to ultimately fabricate reactive micro- and nanopatterns for the area-selective immobilization of biologically relevant molecules via covalent coupling. In addition to full control of reactivity and pattern sizes, biocompatibility and minimized NSA are important for rendering these systems useful as generic platforms. In this context we review in this contribution our recent efforts in this area. We focus in particular on (1) the elucidation of structure-reactivity relationships, (2) the in situ compositional analysis of wet chemical reactions in monolayer-based systems down to nanometer length scales, and on (3) the application and refinement of various micro- and... 

Looking to establish structure-property relationships in a different biological context, Kohn et al and Effah-Kaufmann and Kohn also examined the impact of their polyarylate library on the proliferation of UMR-106 osteoblast-like cells and fibrinogen adsorption as a measure of polymer biocompatibility. An analysis of total DNA concentration as well as metabolic and alkaline phosphatase activity after exposure of UMR-106 osteoblast-like cells to polyarylates revealed no noticeable cytotoxicity, with alkaline phosphatase and metabolic activities equivalent to that observed with tissue culture polystyrene. Polymers containing short ethyl ester side chains stimulated cell proliferation more effectively than more hydro-phobic ester side chains, while no correlations were observed between cell growth and strurtural features of the polymer backbone. 

As stated in Chapter 9, The consilient approach to tissue engineering utilizes biology s own materials and mechanisms, concerned with tissue structure and function, to achieve tissue restoration. The key materials elements are three the capacity of the elastic protein-based material to match the elastic modulus of the tissue to be restored, a remarkable biocompatibility of the pure elastic protein-based material, and the facility to design into the protein-based polymer sequence any desired biologically active sequence, which, by virtue of the innocuousness of the elastic protein-based material, allows proper expression of the incorporated biologically active sequence. This provides the opportunity for the proper functional relationship of protein-based material to the cells and the extracellular matrix of the tissue to be restored. 

The protein adsorption on active carbons is an important process contributing to their biocompatibility and the therapeutic effect of hemoperfusion (Arshady 1999). Covalent binding of proteins to a carbon surface allows one to synthesize adsorbents with high selectivity of action similar to that achieved in affinity chromatography. Despite numerous studies of carbon adsorbent interactions with biomolecules in aqueous media, the influence of the adsorbent structure on the characteristics of the interfacial layer of water in the presence of immobilized proteins ranains unclear. Here the relationships between the structural characteristics of activated carbon SCN and the state of the bound water in the presence of BSA and mouse y-globulin (IgG) physically adsorbed or covalently attached to the carbon surface via carbodiimide coupling are analyzed using adsorption and H NMR methods. 

Some challenges remain concerning the synthesis and structure of these polymers for instance, finding new biocompatible polymers other than PEG. Moreover, in order to define clear structure-function relationships, it is necessary to use new polymerization techniques to obtain well-defined materials rather than randomized polymers [241]. Similarly, more architecturally controlled macromolecules such as dendronized polymers appear to be promising prospects in the field of polycations for gene delivery [242]. 

As the properties of a membrane sinface play significant roles in practical applications, it is important to have the means to characterize and measure those properties. In fact, surface characterization is not only important for understanding the relationship between the membrane structure and its properties but also for guiding surface modification. It is well known that various aspects of a membrane surface, which include chemical composition, morphology and topography, wettability and biocompatibility, can affect the properties and applications remarkably [84],... 

Formariz, T.P., Chiavacci, L.A., Sarmento, V.H.V., SantiUi, C.V., Tabosa do Egito, E.S., Oliveira, A.G. 2007. Relationship between structural features and in vitro release of doxorubicin from biocompatible anionic microemulsion. Colloids Surf. B Biointerf. 60, 28-35. 

The physico-chemical requirements for biocompatibility and bioactivity in terms of compositional limits and the role of additional ions in tailoring new important mechanical and biological properties for specific clinical applications [39] are poorly known at present. In the following we show, by summarizing the results of two case studies, how the relationships can be established and exploited among the structural role of some key elements that appear to control bioactivity. 

Samarendra Maji is working as a postdoctoral researcher in the Department of Chemistry at the Philipps-Universitat Marburg. He obtained his PhD from the Indian Institute of Technology, Kharagpur, India. His research interests includes high performance polymers, biodegradable and biocompatible polymers, structure property-relationship studies of polymers. 

A. Solanki, J. Mehta and S. Thakore, Structure-property relationships and biocompatibility of carbohydrate crosslinked polyurethanes. Carbohydr.Polym.llO 338-344,2014. 

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