NANOSTRUCTURAL CHARACTERIZATION OF GLUTATHIONE- S-TRANSFERASE IMMOBILIZING CHITOSAN MODIFIED SCREEN PRINTED CARBON ELECTRODE BY ATOMIC FORCE MICROSCOPY
Keywords:
Immobilization, Glutathione-s-transferase, Chitosan, Biosensor development, Atomic Force MicroscopyAbstract
Immobilization of a bio-recognition element to the surface of a functional working electrode is
fundamental for effective biosensor development. In this study, the enzyme glutathione-s-transferase (GST)
that constitutes a protein superfamily involving various distinct chemical transformations was introduces as a
versatile tool for the sensing of environmental toxicants. Functional electrode surface was made by self-
assembly of a great bioscaffold chitosan onto screen-printed carbon electrode surface concerning to its
excellent covalent bonding binding of biomolecules. To enhance the enzyme proximity, glutaraldehyde was
employed as an assisting bifunctional cross-linker. The self assembled chitosan layer and the GST
immobilizing nanostructural features were explored by morphological imaging and several quantitative
analyses such as surface grain size and distribution, power spectrum density (PSD) algorithm, fractal
dimension character and other important surface roughness parameters via atomic force microscopy (AFM).
Vertical aggregation of the successive layer was clearly verified in all quantitative approaches. Exceedingly,
a better understanding in the direction of aggregation along with the growth mechanism was obtained by PSD
analysis and the fractal dimension values gained around 2.27 for modified chitosan surface and 2.02 for GST
immobilized chitosan modified screen-printed carbon basement could thus imply for the diffusion limited
model in this growth mechanism.