Non-Enzymatic Lactose Sensor Based on Mxene-NiO Modified Nickel Foam Electrode
Authors: Rifa Asfia Akter , Bar Neshi rani , Alom Nur , Han Tan Kim , Saidur R , Jamal Mamun 
Published: February 2024

Lactose, a disaccharide present in milk and dairy items, serves as the sole carbohydrate source in milk, typically occurring at concentrations ranging from 4.4 to 5.2%. Analyzing the lactose content in milk and dairy products holds significant importance as it serves as a fundamental marker for assessing milk quality and identifying any irregularities [1, 2]. Additionally, lactose intolerance is a prevalent condition in regions like Europe, the Middle East, India, and among the Maasai population in East Africa. As a result, the accurate determination of lactose content holds substantial relevance for both the industry and public health.

In this study, we have developed a non-enzymatic lactose sensor, utilizing a nickel foam electrode that has been enhanced with MXene-nickel oxide (MXene/NiO) composites. This was achieved by synthesizing nanostructures of NiO and physically combining them with MXene on nickel foam (NF). The three-dimensional porous configuration of NF provides a substantial specific surface area, an increased number of diffusion pathways, and convenient accessibility for lactose to engage in electrochemical reactions. To confirm the presence and growth of MXene/NiO on the NF electrode, various characterization techniques were employed, including SEM, EDX, XRD, FT-IR, and UV spectroscopy. In this work, cyclic voltammetry (CV) and amperometric techniques were carried out in a three-electrode system with an oxygen-saturated environment where MXene-NiO/NF, pt wire, and Ag/AgCl were used as a working, counter, and reference electrode respectively. Further investigations were conducted using the modified electrode in 0.1 M NaOH solutions containing lactose, aiming to determine the suitability of the modified electrode for subsequent lactose monitoring. All electrochemical properties of the modified electrode were evaluated through CV in the 0.1 M NaOH solution at a scan rate of 0.05V/s and amperometry in 0.1M NaOH with successive addition of lactose (1 to 3.5 mM). Additionally, the hydrophilic nature of MXene ensures thorough contact with the lactose-containing electrolyte, promoting ample redox reactions. So, this research introduces two key novelties, NF and MXene, both possessing a high surface area and excellent conductivity. Consequently, these innovations offer heightened sensitivity (better than the NiO/CFC lactose sensor of 1.73 mA/mM/cm2), a wide detection range, and faster response time. These findings are particularly noteworthy because conventional non-enzymatic electrochemical sensors documented in the literature that are typically limited to glucose detection and cannot effectively determine lactose concentrations in dairy food samples. Therefore, this approach provides an opportunity to develop a straightforward analytical tool for the rapid and accurate assessment of lactose concentrations in dairy food applications.

Reference

Islam, H. Shao, M. M. R. Badal, K. M. Razeeb, & M. Jamal, 2021, PloS one, 16 (3), e0248142.

Jamal, M. K. Razeeb, H. Shao, J. Islam, I. Akhter, H. Furukawa, A. Khosla, 2019, Scientific Reports, 9, 4659.

M. Razeeb et al., Vertically Aligned Nanowire Array-Based Sensors and Their Catalytic Applications. In: Vestergaard, M., Kerman, K., Hsing, IM., Tamiya, E. (eds) Nanobiosensors and Nanobioanalyses, Springer, Tokyo, 2015.