Chemical Grafting

The covalent binding of biomolecules is generally preferred to the classical adsorption process. In fact, chemical grafting is needed to avoid desorption phe-

FIG. 12 Schematic illustration of modified protein complexation onto chelating compound-containing particles.
FIG. 13 Amount of immobilized RH24K onto chelating poly(NIPMAM) particles as a function of pH.

nomena when adsorption is used. Since the adsorption of proteic materials onto hydrophilic, thermally sensitive particles is mainly temperature dependent, cova-lent coupling has been performed using reactive copolymers [33] and as a function of incubation temperature. As a general result, the chemical grafting yield was enhanced when the adsorption of proteins are first performed. The only work reported in this special field has been investigated using amino-containing thermally sensitive particles, HIV-1 capsid p24 protein, and reactive copolymer poly(maleic anhydride-alt-methyl vinyl ether) (PMAMVE) [32], as is illustrated in Fig. 14. This method was found to be easy and efficient for protein immobilization and orientation onto such stimuli-responsive polymer particles. In addition, the nonspecific immobilization of proteins can be totally monitored.

The adsorption and the desorption of proteic materials onto thermally sensitive colloidal particles (N-isopropylacrylamide-based monomer) have been investigated and discussed as a function of numerous parameters, such as temperature, salinity, pH, surface charge density, and charge nature (anionic and cationic). In addition to the adsorption-desorption studies, the immobilization of proteins via covalent coupling method has been also explored. The pertinent results in those domains are summarized in the following concluding remarks.

The adsorption of protein biomolecules was found and reported to be principally temperature dependent. In fact, the amount of protein adsorbed increased

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