Many studies show that the surface
Considerable attention has been paid to develop enzymatic biosensor by utilizing nanosized biopolymer with large surface area and effective surface functional groups for rapid adsorption. Chitosan (CS) is one of the most extensively examined biopolymer in sensor applications due to its non-toxicity, good mechanical strength, high permeability, and low cost ,  and . It is a linear hydrophilic polysaccharide composed of glucosamine and found abundant in AZ3146 of crabs, shrimps, gladius of squid, insects and microorganisms. Among these various sources, the chitosan produced from gladius of squid shows more open structure, better quality, reactivity, solubility and swelling due to its low molecular hydrogen bonding  and . These chitosan and their derivatives can be used as an effective immobilizing material for electrochemical sensors owing its interesting properties  and . Zhang et al.  reported that, CS deposited onto the electrodes will keep biocompatibility with GOx and retain its natural properties with improved performance. However, the poor electrical conductivity of CS hinders the function of enzymatic biosensor. As a result of relatively poor conductivity, a small layer of CS was coated over the active material to effectively promotes electron transfer kinetics and improve sensitivity and stability of the device ,  and . Moreover, to enhance the conductive properties of sensor, the biopolymer is coated over metallic electrodes or nanoparticles to acquire potential electrical properties along with high surface reaction, excellent catalytic efficiency and strong adsorption ability  and . Noble metals such as gold, platinum and silver are the most extensively studied electrode materials  and . Among these, gold has the most positive reduction potential followed by silver which plays a major role in biosensor . Interestingly, the nano-sized gold particles enhance the overall performance of biosensor and allows the betterment of signal transduction and efficiency ,  and . Yi et al.  demonstrated that the GOx casted over chitosan on Au sub-nanostructured electrode can promotes the electron transfer of enzymatic reaction and enhances the amperometric responses.