Protein adsorption onto polystyrene

Another use for drug conjugation is for signal labeling. For example, the drug will be conjugated to an enzyme in EIA to biotin, avidin, or streptavidin in biotin amplification to a protein for adsorption onto a solid-phase support or to polystyrene beads by direct covalent linkage. 

Among the various techniques for the immobilization of PEG on surfaces, - - graft copolymers of poly(L-ly sine) and poly(ethylene glycol) (PLL- -PEG) are particularly attractive. PLL- -PEG copolymers spontaneously adsorb from aqueous solutions as dense, monomolecular layers onto a rangeofnegatively charged surfaces such as various metal oxides and tissue-culture polystyrene, protecting them against nonspecific protein adsorption moreover,... 

The following protocol for passive adsorption is based on methods reported for use with hydrophobic polymeric particles, such as polystyrene latex beads or copolymers of the same. Other polymer particle types also may be used in this process, provided they have the necessary hydrophobic character to promote adsorption. For particular proteins, conditions may need to be optimized to take into consideration maximal protein stability and activity after adsorption. Some proteins may undergo extensive denaturation after immobilization onto hydrophobic surfaces therefore, covalent methods of coupling onto more hydrophilic particle surfaces may be a better choice for maintaining native protein structure and long-term stability. 

The utilization of classical polystyrene particles or hydrophobic latexes for protein concentrations can induce undesirable phenomena such as protein denaturation and low concentration yields, on account of the high adsorption affinity between both species which may lead to a low desorbed amount. In addition, the use of such hydrophobic colloids in the polymerase chain reaction (PCR) of nucleic acid amplification step generally leads to total inhibition of the enzymatic reaction. The inhibition phenomena can be attributed to the denaturation of enzymes adsorbed in large numbers onto hydrophobic coUoids. The utilization of hydrophilic and highly hydrated latex particles (irrespective of temperature) is the key to solving this problem by suppressing the inhibition of enzyme activity. The purpose of this stage is then to focus on the potential apphcation of thermally responsive poly(NIPAM) particles for both protein and nucleic acid concentrations. 

The mostly used methods to monitor LbL deposition on monodisperse PS-latex particles for various substances are SPLS method and microelectrophoresis. Inorganic (magnetite, silica, titania and fluorescent quantum dots) nanoparticles [32-34], lipids [35-37] and proteins (albumin, immunoglobulin and others) [29, 38, 39] were incorporated as building block for shell formation on colloidal particles. In paper [39] the construction of enzyme multilayer films on colloidal particles for biocatalysis was demonstrated. The enzyme multilayers were assembled on submicrometer-sized polystyrene spheres via the alternate adsorption of poly(ethyleneimine) and glucose oxidase. The high surface area bio-multilayer coated particles formed were subsequently utilized in enzymatic catalysis. The step-wise coating of different lipids alternated with polyelectrolytes was performed by adsorption of preformed vesicles onto... 

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