Stability surface immobilized protein

Conversely, controlled immobilization of enzymes at surfaces to enable high-rate direct electron transfer would eliminate the need for the mediator component and possibly lead to enhanced stability. Novel surface chemistries are required that allow protein immobilization with controlled orientation, such that a majority of active centers are within electrontunneling distance of the surface. Additionally, spreading of enzymes on the surfaces must be minimized to prevent deactivation due to irreversible changes in secondary structure. Finally, structures of controlled nanoporosity must be developed to achieve such surface immobilization at high volumetric enzyme loadings. 

Immobilization has also been shown to stabilize against solvent dena-turation of enzymes. However, here we presented suggestive data on the mechanisms of this stabilization. Only the CPO immobilized in 200-A sol-gel showed any solvent or temperature stabilization. CPO bound to matrices with pores smaller than the protein showed little or no stabilization effect owing to surface immobilization alone. This supports the concept that steric hindrance to protein unfolding within a pore is part of the stabilization mechanism. An unresolved question for the future applications of this research is to increase the overall enzyme activity or loading. 

One approach to develop more biologically compatible surfaces for immobilizing proteins is to incorporate a matrix, such as a hydrogel, as an interface between the protein and the solid surface (Burnham et al. 2006). The entrapment of enzymes in a hydrogel layer provides excellent long-term stability and the possibility to adjust the polymer matrix to the specific needs of a certain enzyme. Hydrogels are useful for linking proteins to solid surfaces because their hydrophilic nature and porous structure can help to keep these labile molecules in the native functional state. 

Chemical modification of oxide surfaces, immobilization of polymers on them, addition of different surfactants or solvents (e.g., alcohols) to the aqueous suspensions can be responsible for alterations in the hydrogen bond network and the free energy of the interfacial layers, surface charge distribution, and so on, which can affect the dispersion stability and other characteristics of both suspensions and powders prepared from these suspensions [9-15]. The last with adsorbed molecules (e.g., drugs, PVP, proteins, cellulose, etc.) can be of interest for medicine, biotechnology, etc. 

DNA, RNA, and protein-modified electrodes can be prepared using both carbon and mercury surfaces [283]. Stability of immobilization of NAs at HMDE and graphite electrodes is very good [270]. AdTSV has been widely applied to various kinds of NA and protein studies [13, 15, 249, 270, 281, 284, 285]. Compared with conventional voltammetry, AdTSV has many advantages that are mainly due to the separation of the biomacromolecule adsorption from the electrode processes. These advantages include (1) reduction of the sample volume to 3 to 10 microliters, (2) elimination of interferences by low molecular mass substances that are washed off in AdTSV, (3) adsorption of the biomacromolecule on the electrode from media not suitable for the conventional voltammetric analysis, (4) in studies... 

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