Protein-functionalized colloidal particles

Fractal Structures and Aggregation Kinetics of Protein-Functionalized Colloidal Particles... 

In this section, we study flocculation processes arising in protein-functionalized colloidal particle suspensions. It is divided into two parts. Part (1) is devoted to the influence of the electrical state of the protein-particle complex and part (2) addresses the importance of short-range interactions and the protein size. Before we expose the experimental results, a short description of the experimental details will be given. 

STRUCTURAL COEFFICIENT FOR FRACTAL AGGREGATES OF PROTEIN-FUNCTIONALIZED COLLOIDAL PARTICLES... 

For a complete functional study of a biological pathway, it is often necessary to confirm the important protein interactions by in vivo experiments. This can be done by demonstrating protein localizations on a microscopic level, for instance, by tagging proteins with the green fluorescent protein or localizing them with antibodies and colloidal gold particles using an electron microscope. Additional, very specific biochemical experiments are often required to confirm the putative protein function. 

Owing to the diverse chemical nature of functional groups in proteins and polysaccharides, they are prone to a variety of types of molecular interactions, both in bulk aqueous media and at air-water or oil-water interfaces. To a first approximation one may consider an adsorbed layer of biopolymers at the interface as simply a special type of highly concentrated biopolymer solution. Thus, the same variety of interactions that are typically found for biopolymers in a bulk aqueous media also occur in biopolymer adsorbed layers at the interfaces in food colloids. Moreover, these same molecular interactions are also involved in the close encounters between pairs of colloidal particles covered by adsorbed biopolymer layers. In the rest of this chapter we shall briefly remind ourselves of the main basic types of intermolecular interactions readers requiring more detailed background information are directed to other sources (Cantor and Schimmel, 1980 Lehninger, 1982 Israelachvili, 1992 Dickinson, 1998 Finkelstein and Ptitsyn, 2002 McClements, 2005, 2006 Min et al., 2008). 

Even larger probes of bent and kinked DNA are 40 A photoluminescent mineral colloidal particles of CdS [247-253]. These nanoparticles are approximately the size of proteins and can be made in a variety of sizes ( 20-100 A) and decorated with a variety of surface groups [267-279]. The emission spectrum of a nanoparticle solution depends on particle size and surface group synthetic procedures for CdS and other semiconductor nanoparticles have been developed so that the emission can be tuned throughout the visible spectrum and into the near infrared [267-279]. Moreover, the photoluminescence of CdS is sensitive to adsorbates [280-289], and thus these nanomaterials can function as luminescent chemical sensors. 

The construction of LbL multilayer films of biomaterials on colloid particles is of particular interest in applications where a microscopic contact is essential, such as protein interaction and cell communication, and where high surface area is desirable, such as in catalysis. For example, enzyme LbLs on particle surfaces are useful for biorelated catalysis since microscopic objects of higher surface area can potentially yield higher enzymatic reaction efficiencies than their planar film counterparts. If the LbL assembly is conducted on microparticles with certain functions, we can... 

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