Preparation Of Thermally Sensitive Particles

The adsorption of protein onto colloidal particles has been widely investigated, discussed, and reported as evidenced by the numerous published papers and extensive reviews. Based on these reports the adsorption of proteins is mainly related to the hydrophobic character and the charge density of the considered polymer support. In fact, the amount of proteins absorbed onto polystyrene latexes generally used in biomedical diagnostics was found to be high. Then, in order to control the proteic materials' immobilization onto colloidal polymer support, the adsorption should be well controlled. The adsorption of proteins can be dramatically reduced or totally suppressed when the adsorption was investigated on hydrophilic surfaces. However, the total reduction of protein adsorption may also reduce the covalent immobilization of such biomolecules when necessary. Then the challenge is to elaborate materials on which the adsorption can be controlled as a function of a given external stimulus. To satisfy such an objective, various polymerization conditions and methodologies have been investigated. The basic considerations needed to target appropriate the morphology are summarized in Fig. 2. In this domain, poly(N-isopropylacryl-amide) [poly(NIPAM)]-based microgel particles have been elaborated [10] and evaluated in investigations of protein adsorption as a function of various parameters [11].

FIG. 2 Polymerization of N-aLkyl(meth)acrylamide monomer derivatives in aqueous phase.

The preparation of poly(NIPAM)-based particles bearing the volume phase transition temperature (Tvpt) were prepared under three morphologies; microgel, core-shell and composite (Fig. 3). In this chapter, only the pertinent results on the poly(NIPAM)-based particles used in protein adsorption study is presented below.

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