Effects of Surface Functionalization and Organo-Tailoring of Synthetic Layer Silicates on the Immobilization of Cytochrome c

Abstract

The utility of various synthetic hectorites for the preparation of active enzyme complexes by simple adsorption processes was examined. The smectites compared include commercially available Laponite RD, mesostructured hectorites (both with and without organic template), and silane-modified mesostructured hectorite. The complexes were evaluated by the amount of cytochrome c that was incorporated and the fraction of enzyme available for redox reaction. The quantity of adsorbed cyt c was determined by optical absorption spectroscopy of the supernatant solution, yielding enzyme densities that ranged from 20 to 50 wt %. There was no correlation between weight percent loading and either the surface area or the pore volume of the clay mineral. Rather, other characteristics such as surface compatibility appear to play the major role in this regard. Immobilized enzyme conformation was examined by EPR. Qualitative information regarding protein stability and redox activity was also obtained by chemical reduction experiments. These studies revealed the effects of organo-tailoring of the inorganic surface in terms of steric hindrance of enzyme in active conformation and denaturation within a clay pore microenvironment.

Nanotechnology, nanotoxicology, and neuroscience

“…Dramatic responses observed in biomolecules and biomolecular processes involved in interfacial phenomena that involve inorganic surfaces are well demonstrated in biomineralization processes (Zaremba et al, 1996), biomolecular chromatographic separations (Kimura et al, 2004), supported enzyme activities and lifetime (Carrado et al, 2004; Han et al, 2002) and protein folding and denaturation (Charache et al, 1962). Mentioned earlier in Section 2.2, the development of potent wound-dressing materials (blood clotting agents) that are capable of arresting hemorrhage due to traumatic injury is another emerging application using materials chemistry to control bioprocesses (Ellis-Behnke et al, 2006; Fischer et al, 2005; Marris, 2007; Ostomel et al, 2006a) and one of the most effective wound-dressing materials currently available is a nanoporous zeolite called QuikClot® (QC) (Z-Medica).…”

On Binary-State Phyllosilicate Automata

“…Phyllosilicates are used in the development of nano-materials, nano-wires and patterned surfaces for nano-biological interfaces [Monnier et al, 1993;Carrado et al, 2004;Suh et al, 2009]. They are also employed, in a form of cation-exchanged sheet silicates, as catalysts in chemical reactions [Ballantine et al, 1984], e.g.…”

Directly Grown K0.33WO3 Nanosheet Film Electrode for Fast Direct Electron Transfer of Protein

“…[1,9] Thereby, it is of great importance to shorten the electron-tunneling dis-tance between the redox center of the protein/microbe and the electrode to enable direct electron transfer. [9] Recent studies have demonstrated that direct electrochemistry can be realized by uniquely nanostructured electrodes, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] which could access the embedded redox centers of proteins or microbes while increasing surface area, enhancing mass transport and controlling the electrode microenvironment. [1,[10][11][12][13][14] Further, some physico-chemical properties, including conductivity, hydrophilicity and interfacial resistance are essential to enhance the direct electron transfer rate.…”

“…[11] Highly porous metal oxide nanostructures (TiO 2 , ZnO, etc.) [8,[18][19][20] and some layered inorganic materials (clay, phosphates, titanate) [21][22][23][24] are superior to many carbon and metal nanostructures in hydrophilicity and sometimes in specific surface area. However, a lack of good electrical conductivity limits their performance in direct electrochemistry.…”