Browsing by Author "Viswanathan, Sowmya"

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    Graphene–protein field effect biosensors: glucose sensing
    (Elsevier, 2015) Viswanathan, Sowmya; Narayanan, Tharangattu N.; Aran, Kiana; Fink, Kathryn D.; Paredes, Jacobo; Ajayan, Pulickel M.; Filipek, Slawomir; Miszta, Przemyslaw; Tekin, H. Cumhur; Inci, Fatih; Demirci, Utkan; Li, Pingzuo; Bolotin, Kirill I.; Liepmann, Dorian; Renugopalakrishanan, V.
    Chronic diseases are becoming more prevalent, and the complexities of managing patients continue to escalate, since their care must be balanced between the home and clinical settings. Diabetes is the most advanced example, where self-monitoring has been shown to be necessary. Glucometers are point-of-care (POC) devices that have become standard platforms at home and clinical settings. Similarly, many other POC biosensors have also been developed. Enzymes are often used in these sensors because of their specificity and the reaction products can be electrochemically transduced for the measurement. When enzymes are immobilized to an electronically active substrate, enzymatic reactions can be transduced by direct electron transport. This paper describes an approach for the development of graphene-based POC devices. This includes modifying enzymes for improved performance, developing methods to bind them to the graphene surface, incorporation of the functionalized graphene on a field-effect transistor (FET), and integration into a microfluidic device suitable for home use. This paper describes an approach for the development of a graphene-based POC biosensor platform using glucose as an example of target molecule.
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    Structural determination of Enzyme-Graphene Nanocomposite Sensor Material
    (Springer Nature, 2019) Rai, Durgesh K.; Gurusaran, Manickam; Urban, Volker; Aran, Kiana; Ma, Lulu; Qian, Shuo; Narayanan, Tharangattu N.; Ajayan, Pulickel M.; Liepmann, Dorian; Sekar, Kanagaraj; Álvarez-Cao, María-Efigenia; Escuder-Rodríguez, Juan-José; Cerdán, María-Esperanza; González-Siso, María-Isabel; Viswanathan, Sowmya; Paulmurugan, Ramasamy; Renugopalakrishnan, Venkatesan; Li, Pingzuo
    State-of-the-art ultra-sensitive blood glucose-monitoring biosensors, based on glucose oxidase (GOx) covalently linked to a single layer graphene (SLG), will be a valuable next generation diagnostic tool for personal glycemic level management. We report here our observations of sensor matrix structure obtained using a multi-physics approach towards analysis of small-angle neutron scattering (SANS) on graphene-based biosensor functionalized with GOx under different pH conditions for various hierarchical GOx assemblies within SLG. We developed a methodology to separately extract the average shape of GOx molecules within the hierarchical assemblies. The modeling is able to resolve differences in the average GOx dimer structure and shows that treatment under different pH conditions lead to differences within the GOx at the dimer contact region with SLG. The coupling of different analysis methods and modeling approaches we developed in this study provides a universal approach to obtain detailed structural quantifications, for establishing robust structure-property relationships. This is an essential step to obtain an insight into the structure and function of the GOx-SLG interface for optimizing sensor performance.