Artificial biopolymers

Our general strategy is based on the synthesis of artificial polymeric compounds which are made of naturally occurring building blocks and generate metabolites upon abiotic degradation (artificial biopolymers). 

Fig 3 shows the main characteristics of macromolecules made according to this strategy, together with the various factors that can be used to diversify the properties and to adjust them to the list of required specifications of a given biomedical or pharmacological triplication. 

Let US consider some examples of bioresorbable polymeric compounds synthesized according to this strategy. 

1 Aliphatic polyesters derived from lactic and glycolic acids 

Nowadays, the most attractive family of bioresorbable polymers is composed of poly(a-hydroxy acids) derived from lactic and glycolic acids (PLAGA) (Table2) 

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Biopolymers and Artificial Biopolymers in Biomedical Applications, an Overview... 

In this contribution, we will successively recall the interest and the limits of biopolymers and of artificial biopolymers with regard to temporary therapeutic applications, degradable polymeric compounds being unsuitable to uses as biostable devices. However, we will first recall the problons raised by the concept of biodegradation and the use of temporary therapeutic applications, with the aim of showing that, in therapeutic applications, it is the fete of the device that is important and not its degradability nor its biodegradability. 

Figure 3. Schematic representation of an artificial biopolymer composed of different repeating units linked through labile bonds and diversified by using various structural factors such as chirality, repeating unit distribution, substitution and functi< aiization.

Vert, M., 2001, Biopolymers and Artificial Biopolymers in Biomedical Applications, an Overview. In Biorelated Polymers, Sustainable Polymer Science and Technology (E. Chiellini, H. Gil, G. Braunegg, J. Buchert, P. Gatenholm, and M. Van der Zee, eds.), Kluwer Academic/PIenum Publishers, pp. 63-79. 

Research Centre for Artificial Biopolymers, UMR CNRS 5473, University of Montpellier 1, Faculty of Pharmacy, 15 Avenue Charles Flahault, B.P. 14491,34093 Montpellier Cedex 5, France... 

Albumin - [BLOOD, ARTIFICIAL] (Vol 4) -clinical assay for [AUTOMATED INSTRUMENTATION - CLINICAL CHEMISTRY] (Vol 3) -detection of [BIOPOLYMERS - ANALYTICAL TECHNIQUES] (Vol 4) -mineral nutrient carrier [MINERALNUTRIENTS] (Vol 16) -quimdme binding to [CARDIOVASCULAR AGENTS] (Vol 5) -role in pharmacokinetics [PHARMACODYNAMICS] (Vol 18) -sex hormone complex [HORMONES - SEX HORMONES] (Vol 13)... 

Zhao, C.H., Yao, J.M., Masuda, H., Kishore, R., and Asakura, T. "Structural characterization and artificial fiber formation of Bombyx mori silk fibroin in hexafluoro-iso-propanol solvent system". Biopolymers 69(2), 253-259 (2003). 

Lohmann, R., Schneider, G. Wrede, P. (1996). Structure optimization of an artificial neural filter detecting membrane-spanning amino add sequences. Biopolymers 38,13-29. 

Recently, we have demonstrated that biopolymers such as DNA and peptides can be chemically reconstructed, and thereby act as template molecules for homogeneous or heterogeneous metal arrays in a programmable manner. This chapter covers our recent approaches to metal arrays on artificial DNAs and cyclic peptides. 

Formation of condensation structures is the reason for gelation of solutions of various natural and synthetic polymers. Gelation may be accompanied by conformational changes of macromolecules, which occur in the case of gelling of gelatin and other biopolymers, or in the course of chemical reactions. For instance, according to Vlodavets, partial acetalization of polyvinyl alcohol with formaldehyde in acidic medium under the conditions of supersaturation yields fibers of polyvinyl formals which further undergo coalescence and form a network with properties similar to those of leather (and artificial leather substitute). 

Biomedical materials include metals, ceramics, natural polymers (biopolymers), and synthetic polymers of simple or complex chemical and/or physical structure. This volume addresses, to a large measure, fundamental research on phenomena related to the use of synthetic polymers as blood-compatible biomaterials. Relevant research stems from major efforts to investigate clotting phenomena related to the response of blood in contact with polymeric surfaces, and to develop systems with nonthrombogenic behavior in short- and long-term applications. These systems can be used as implants or replacements, and they include artificial hearts, lung oxygenators, hemodialysis systems, artificial blood vessels, artificial pancreas, catheters, etc. 

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