Project Summary Expansion of tandem DNA repeats cause more than forty genetically transferrable disorders, which affect 4 million people every year. Current state-of-the-art diagnostic technologies for genetic testing for length mutations have their own limitations such as clogging of protein nanopores, requiring labelling steps, frequent false positive/negative results, or short basepair read length. To overcome the limitations that hamper the current biomedical science, there is a critical need to develop new platforms founded on thorough basic science. This AREA proposal involving mainly undergraduate researchers investigates intrinsic character of tandem DNA repeats interfaced with MoS2 surfaces that may manifest into label-free sensing platform for repeat mutations in future. The PI hypothesizes that DNA repeats can produce sequence- and length-dependent charge transfer signals due to the differential affinity of nucleobases for two-dimensional materials, i.e. molybdenum disulfide (MoS2). This is the critical piece of information needed to confirm through a rigorous study. Based on encouraging preliminary results, current project is designed to fundamentally investigate DNA/MoS2 interfaces in detail by electrochemical and surface probe microscopy techniques. In the specific aims, the PI plans to (1) investigate sequence-dependent charge transport at TNR/2D nanomaterials interface, and (2) investigate their behavior with respect to sequence length. The results will also be compared with concentration and conformations effects on the charge transfer character. This AREA proposal will expose the undergraduate researchers to high-quality research in surface chemistry and materials science, which has ultimate application in biomedical research to improve public health. Upon completion, we will be in better position to apply DNA/2D materials for selective and sensitive detection of repeat mutations, which will ultimately improve the lives of millions of individuals.