Investigation Of The Electrochemical Properties of Hydroxyapatite Immobilization Material for Potential Cytosensor Fabrication

Abstract

Biomedical diagnostics is moving towards an effective and rapid diagnosis of which biosensor fabrication is the paradigm shift. Despite the successes obtained using sensing platforms, detachment of biorecognition elements from the transducing surface remains a hurdle to overcome. Good attachment of biorecognition elements to the transducing surface determines the sensitivity and specificity of the biosensor. In the area of cancer biosensing, gold, graphene, chitosan, and conducting polymers are among the few materials that have been exploited for effective immobilization, but they faced detachment problems. To curb these detachment problems, blends of cancer immobilizing materials and other molecules have been proposed but fabrication methods make the immobilizing material expensive. Thus, this thesis aimed at investigating the use of cost-effective hydroxyapatite (HAp) material synthesized from Achatina achatina snail shells (SHAp) for the direct immobilization of cells. SHAp was mixed with 3,4-ethylene dioxythiophene: poly 4- styrene sulfonate (PEDOT: PSS), a conductive polymer to increase the electrochemical responses of the SHAp forming a SHAp/PEDOT: PSS blend. The SHAp/PEDOT: PSS blend was used to modify a screen-printed electrode (SPCE) by a dropped coating approach after which cell-lines including pheochromocytoma (PC-12), human embryonic and kidney cells (HEK-293T) immobilized on the modified SPCE. Red blood cells (RBC) were used as a control. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were performed to record the cell proliferation signals. The CV results showed low peak currents for cell-lines (50 µA for HEK-293T and 120 µA for PC-12) and high peak current for the control RBC (230 µA). The EIS showed impedance values of 0.70 and 0.62 mΏ for HEK-293T and PC-12, respectively, and 0.52 mΏ for RBC. The findings demonstrate that SHAp is able to differentiate the proliferation signals of cells through potentiometric and impedimetric measurements. The unique current difference among these cells could be used as potential markers for the rapid detection of cancer cells at a low cost in future studies.