1IntroductionOver the past few decades,t he studies on direct electron transfero fr edox activep roteins or enzymes have received much interesto wing to their application in different fieldsi ncluding biosensors and biofuel cells [1][2][3].I n electrochemical analysis,t he determination of glucose is very important in different fields especially in the clinical diagnosis.D iabetes mellitus is them ost common endocrine disorder,w hich leadst om ajor health problems.T he World Health Organization (WHO) has reported that an approximately 171 million people are affectedb yd iabetes and it may increase to 366 million by 2030 [2].T he higher and lower blood glucose level from the normal glucose range (4.4-6.6 mM) always result in metabolic disorders. Glucose oxidase( GOx) is widely used for the construction of glucose biosensors due to its high selectivity towards glucose [4].H owever, the immobilization of GOx on the conventional electrodes is quite difficult,s ince the redox active sites of GOx is deeply buriedi nside and covered by at hick protein layer. Hence,d ifferent nanomaterials such as carbonn anomaterials,m etal nanoparticles, metal oxides,c onducting polymers and so on [4-10] have been used for immobilization to achieve directe lectrochemistry of GOx, Carbon nanotubes are well known carbon nanomaterials which have been used for constructiono fg lucose biosensors owing to its unique structural properties.C arbon nanotubes have also integrated with conductingp olymers, metal oxides,c arbon nanomaterials and metaln anoparticles have also been used for construction of glucoseb iosensor based on the direct electrochemistry of GOx [ 5]. Recently,r educed graphene oxide (RGO) or graphene has been used as an ovel electrode materialf or different potential applications including constructiono fg lucose biosensors [7].R GO is a2 Dc arbon nanomaterial from graphitic family and has shown excellent electrochemical properties compared to other graphitic carbon nanomaterials [ 11,12].H owever, the direct immobilization of redox proteins on pristineR GO is quite difficult due to van der Waals interactions betweeni ndividual RGO sheets [13][14][15].T oo vercome this problem, different approaches or modifiers have been used with RGO to immobilize the GOxa nd enhance the biocompatibility of RGO.Them odifierss uch as nafion, sodiumd odecyl sulfate and chitosan have been used with RGO to enhance the biocompatibilityo ft he RGO [16][17][18].T he composite of RGOw ith carbon nanomaterials,m etal nanoparticles, metal oxides and conducting polymers have also been used for the immobilization matrix of GOx [19][20][21][22][23].R eAbstract:Asimple glucose biosensor has been developed based on direct electrochemistry of glucose oxidase (GOx) immobilizedo nt he reducedg raphene oxide (RGO) and b-cyclodextrin (CD)c omposite.Awell-defined redoxc oupleo fG Ox appears with af ormal potential of~À0.459 VatR GO/CD composite.Ah eterogeneous electron transfer rate constant (K s )h as been calculated for GOx at RGO/CD as 3.8 s À1.T he fabricated...

The bio-mediated nanomaterials have expected growing responsiveness due to an increasing requirement to develop naturally nonthreatening technologies in nanomaterial synthesis. Biotic ways to prepare nanomaterials through extracts from the plant (includes stems, leaves, flowers, and roots) and microorganisms were recommended as likely replacements for physical and chemical routes due to their solvent medium and environment eco-friendliness and nontoxicity. This chapter focuses on electrocatalyst prepared by various bio-mediated synthetic ways and used as a green and eco-friendly electrocatalyst to recognize extensive chemical and biologically essential molecules with improved selectivity and sensitivity with low detection limit. The bio-mediated nanocomposite formation processes and their unique properties surface functionalization and electron transfer mechanism discussed in connection with the design and fabrication of sensors. As a final point, the encounters and prospects in developing bio-mediated nanomaterials-based electrochemical sensing technology was outlined.