STUDIES ON GRAPHENE OXIDE BASED NANOCOMPOSITES AND THEIR APPLICATIONS

Abstract

The research work reported in this thesis states the fabrication of a biosensing electrode that provides quantitative information for the detection of water pollution phenolic compounds. Bio-sensing is achieved by utilizing a biological recognition element that must be in direct spatial contact with a transducer which in turn converts the biological signal to measurable electrical signal. Biosensors chiefly consist of two parts viz, bio-recognition element and sensing element. Generally, enzymes, antibodies, DNA, etc., are used for the specific detection of analyte. Biosensors used in multidisciplinary fields of science and technology still have a lot of space for innovation. Recently, a new generation of biosensors has become popular and designed to assist in combining biological molecules with a biocompatible nanotechnology conducting framework. Organic chemicals are being regressively used for development, modernization, and urbanization for industries and domestic purposes. There is always a considerable quantity of untreated effluents that run into the water system. Hydroquinone and catechol are some of the most widely used chemicals in industries and are the main constituents in photography, stabilizers in paints, dye intermediates, etc. However, even low concentration acquaintance with phenol derivatives in water reservoirs can cause numerous health issues. Graphene oxide (GO) has attracted much attention in biosensor application. This is due to owing its distinct electrical features, high surface area, superior conductivity, excellent charge transfer capability, flexibility of functionalization and biocompatibility. Furthermore, due to its high electrocatalytic activity and potential to exhibit direct electron transfer property, GO has been investigated as a sensitive vi platform in electrochemical biosensors. The incorporation of nanomaterials such as metal oxides and metal sulphides has sparked considerable attention due to possibility of tailoring the specific features of each component into single material. Additionally synergetic effects of these materials have influenced the biosensor performance, resulting in the better sensitivity and selectivity. Thus, the present study focusses on the synthesis, characterization and application of rGO (reduced graphene oxide) based nanocomposites with MgO and MoS2, in the development of efficient electrochemical biosensors for the sensitive and selective detection of hydroquinone using enzymatic and non-enzymatic approaches. The detection was carried out using amperometry technique wherein, synthesized nanocomposites were electrophoretically deposited onto ITO glass substrate. Under enzymatic approach, laccase enzyme has been immobilized onto modified ITO sheets. The fabricated platform was found suitable for detection of phenolic water pollutants under spiked river and tap water samples, proving its efficiency.