A Comparative Analysis of ZnO Nanorods and Nanopencils Towards Amperometric Biosensing Applications.

In this work, ZnO Nanorods (ZNR) and Nanopencils (ZNP) were synthesized over Platinum (Pt) coated glass substrate by simple and low-temperature hydrothermal process for large-scale fabrication towards biosensing applications. The two types of morphologies have been obtained by using strong oxidizing agent viz KMnO₄ as an additive and replenishing the growth solution during the hydrothermal growth process. It was observed that incorporation of additive and replacement of growth solution has greatly influenced structural and electrochemical properties of ZNR/ZNP in terms of morphology, aspect ratio, and charge transfer hindrance. The aspect ratio has been found to increase by approximately three times from ZNR to ZNP which facilitated higher enzyme loading over ZNP as compared to ZNR. Moreover, electrochemical charge transport resistance was found to decrease by 36 times with changes in morphology and aspect ratio. Hence, significant variation in performance of as-fabricated enzymatic biosensor was observed. Amidst both the types of biosensors four-fold increment in sensitivity was found from ZNR to ZNP along with fast response time of 5s and a linear range of operation of 0.5-7.5 mM. The obtained results revealed that aspect ratio could be tuned efficiently by replacing the growth solution during hydrothermal growth which cognitively effects enzyme loading thereby influencing different figure of merits of the biosensor.