Tuning Mn-MOF by Incorporating a Phthalocyanine Derivative as an Enzyme Mimic for Efficient EGFET-based Ascorbic Acid Detection

In this study, we present the effect of catalytic performance in Mn-MOF upon incorporating varied concentrations of phthalocyanine derivative (H₂PcP₈OH₁₆) for ascorbic acid detection in an extended gate field-effect transistor (EGFET) configuration. The fabricated Mn-OM-MOF-2/CP electrode demonstrated notable selectivity toward ascorbic acid in physiological conditions of sweat, with a sensitivity of 71.375 μA·mM^–1·cm^–2, a response time of less than 6 s, and a linear range from 5 to 240 μM. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.26 and 0.78 μM, respectively. Remarkably, the prepared electrodes followed the Michaelis–Menten kinetics. Among them, the Mn-OM-MOF-2/CP electrode demonstrated the highest affinity for ascorbic acid, with a K_m value of 0.142 mM. To gain deeper insights into the charge transfer mechanism during ascorbic acid interaction with Mn-OM-MOF-2/CP, we employed the scanning Kelvin probe (SKP) technique and conducted post-FTIR analysis to understand the sensing mechanism. Additionally, post-UV–visible (UV–vis) measurements were performed to explore how the incorporation of the phthalocyanine derivative enhances affinity. Additional studies using standard artificial sweat have confirmed the Mn-OM-MOF-2/CP electrode’s good recovery. Overall, the results of the EGFET method demonstrated the suitability of the Mn-OM-MOF-2/CP electrode for rapid, noninvasive, single-use ascorbic acid detection in 1× phosphate buffer saline (1× PBS).