Cancer currently stands as the second-leading cause of death worldwide. Studies reveal colorectal cancer (CRC) to be the 4th leading cause of mortality due to cancer. It is estimated that about 30% of CRC cases are hereditary, of which 5% are attributed by known syndromes, particularly Lynch Syndrome. Lynch Syndrome (LS) is caused by loss or malfunction of proteins responsible for DNA mismatch repair proteins (MMR), mostly MLH1 and MSH2, causing increased risks of developing CRC. Despite the small percentage accounted with the disease, the severity of the illness still remains immense since 80% of these patients eventually develop CRC and an overwhelming 40-60 % of female patients develop endometrial cancer, the major form of cancer in women in the developing nations. This pilot study aims to fabricate a DNA-graphene-polypyrole (DGP) based biosensor to diagnose deficiency of functional MMR proteins present in patients at a scale of less than ng/ ml. Fundamental understanding of interactions at the interface of biological molecules, such as proteins, and nanomaterials is therefore crucial for developing such biocompatible hybrid materials and biosensing platforms. Conductive nanomaterials-based biosensors offer the advantage of higher sensitivity and reliable diagnosis mainly due to their superior specific surface area and ballistic conductivity. Such films that immobilize proteins can synergize the properties of transducers and molecular recognition elements in order to improve biosensor performance and diversity. Here we report for the first time, using a combined molecular dynamics simulations and experimental approach, the interactions between avidin and a graphene surface, which is being developed as a sensing platform for early detection of DNA mismatch repair proteins. We find that the interactive forces between avidin and graphene are mainly hydrophobic, along with some van der Waals, electrostatic and hydrogen bonding interactions. Notably, the structure and function of the avidin molecule is preserved after its adsorption on the graphene surface. The MD results agree well with scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) analysis of avidin immobilized on a graphenated polypyrrole (G-PPy) conductive substrate, which confirm adsorption of avidin on graphene nanoplatelets and corresponding changes in electrical impedance, respectively. A final analysis is being conducted to confirm our hypothesis
