Biomaterials chemical modifications

Unfortunately, the modification of the side chain is not a generally applicable approach. Among the major, naturally occurring amino acids, only L-lysine has a chemically reactive side chain that would be as readily available for chemical modification as the side chain of glutamic or aspartic acid. Since, however, poly (L-lysine) is known to be toxic (10), its derivatives cannot be candidates for generally applicable biomaterials. Thus, most of the poly(amino acids) that have so far been suggested as biomaterials are derivatives of gluteunic or aspartic acid or copolymers of such derivatives with leucine, methionine, or a limited number of additional amino acids (11). 

Chemical modification of the biomaterial with photoisomerizable units represents one approach to controlling intermolecular affinity interactions (Scheme 2(A)). In one photoisomer state of the biomaterial, its tertiary, biologically active structure is retained and the formation of the intermolecular complex is facilitated. In the complementary photoisomer state, the bioactive binding site is distorted and the formation of the intermolecular recognition complex is switched off. The bind-... 

Tiller JC, Bonner G, Pan L-C et al. (2001) Improving biomaterial properties of collagen films by chemical modification. Biotechnol Bioeng 73 246-252... 

FIGURE 3.6 Evidence in support of chemical modifications occurred onto biomaterial leading to enhanced sorption. 

Not all ILs are good solvents for proteins, however. There is the interesting example of lipase. Lipase is soluble in both aqueous and organic solvents, so it can be easily solubilized in ILs. Certain lipases even become dispersed or dissolved in some ILs. Since lipase is a very stable enzyme, it catalyzes the hydrolysis of lipids. Enzymatic activity is reported to be maintained in ILs [1]. There is not much published on the solubilization of biomaterials in ILs. In the present chapter we introduce a procedure to use in solubilizing biomaterials in ILs. First we consider the preparation of the IL, and then the chemical modification of biomaterials suitable for dissolution. We have found this procedure helpful when we tried to use electrochemicaUy active biomaterials in ILs. 

In contrast to lipids, polymer chemistry allows various chemical modifications to introduce functionality and make polymers responsible to environmental stimuli (pH, temperature, ions, light, etc.). In biosciences, responsiveness to external stimuli is a crucial factor, especially in drug release and construction of biomaterials. 

Dee KC, Andersen TT, Bizios R (1998) Design and function of novel osteoblast-adhesive peptides for chemical modification of biomaterials. J Biomed Mater Res 40(3) 371-377... 

The versatile properties and manufacturability of polymers has evoked immense interest in developing a class of biomaterials with the potential to interface with biological systems [1]. However, polymers are prone to pathogenic attack resulting in deterioration of properties, malfunction and so on. Various methods such as the ionic binding technique, incorporation of metal particles/metal oxides/nanoparticles (NP) and physico-chemical modification via, e.g., the addition of quaternary ammonium salts and blending with antimicrobial polymers, have been explored for the fabrication of bactericidal materials [2], However, these methods can result in reduced biocompatibility, cytotoxicity and eco-toxicity. 

Because of the presence of a large number of end functionalities, several chemical modifications are possible for hb polymers that make them suitable candidates for different end-use application. New analytical techniques have allowed the characterization of these materials. From an industrial point of view, hb polymers have made impressive advances as additives and rheology modifiers. Nowadays, they are also used in coatings, catalysts, sensors, biomaterials. 

---