Effect of Coordinated Solvent Molecules in Cu-MOF on Enzyme Free Sensing of Glucose and Lactate in Physiological pH

Abstract

Developing a nonenzymatic sweat sensor for selective determination of glucose and lactate holds great significance in clinical diagnostics. Among various catalysts, transition metal-based metal-organic frameworks (MOF) have recently drawn more attention due to their tunable porosity and enhanced electrocatalytic activity. The presence of solvent molecule in the framework can influence both structural and electrochemical properties. In the present work, Copper-terephthalate (CuBDC) MOF was synthesized in a solvothermal method with different time durations. The effect of coordinated solvent molecules on the metal centre on structural and electrocatalytic properties was systematically investigated using various characterization techniques. As most of the copper-based composites reported so far showed performance in an alkaline medium, we demonstrate the detection of glucose and lactate in a neutral medium that enables direct analyte measurement from the body fluid. Electrochemical studies indicate that the solvated structure shows superior sensitivity to the desolvated MOF for glucose and lactate. The high sensitivity of solvated MOF is attributed to the favourable solvent exchange mechanism and ion diffusion through the channels of MOF. Furthermore, CuBDC12E and CuBDC48E show negligible interference toward competing analytes. The proposed sensor also exhibits good sensing performance in artificial sweat, making it suitable for a non-invasive, practical sweat sensor.

A review on the recent advancements in nanomaterials for nonenzymatic lactate sensing

“…A study on the effect of complexation with different solvent molecules on a Cu-terephthalate MOF for nonenzymatic lactate sensing in physiological pH was reported. 110 The study revealed that solvated MOF shows better sensitivity than desolvated MOF for lactate oxidation. The better performance of the solvated MOF was due to the feasible solvent exchange mechanism and ion diffusion inside the MOF.…”

“…A few MOF materials have been used for enzyme-free lactate sensing so far. [104][105][106][107][108][109][110] Wang et al reported the fabrication of flexible amine-functionalized graphene paper (NH 2 -GP) modified with the 2D-oriented assembly of Cu 3 BTC 2 MOF. 104 The modular approach facilitates high MOF particle loading and organized monolayer disposition on NH 2 -GP to form the paper electrode.…”

“…The unique properties, along with the large surface area and numerous pores, enabled easy adsorption of analytes on the MOF surface, increasing the sensitivity. A few MOF materials have been used for enzyme‐free lactate sensing so far 104–110 . Wang et al reported the fabrication of flexible amine‐functionalized graphene paper (NH 2 ‐GP) modified with the 2D‐oriented assembly of Cu 3 BTC 2 MOF 104 .…”

“…The excellent catalytic activity of the catalyst was attributed to the larger ECSA with a hierarchical structure and numerous pore sites. A study on the effect of complexation with different solvent molecules on a Cu‐terephthalate MOF for nonenzymatic lactate sensing in physiological pH was reported 110 . The study revealed that solvated MOF shows better sensitivity than desolvated MOF for lactate oxidation.…”

Supported NiOx Nanocatalysts on Graphene for Nonenzymatic Lactate Sensing

“…Several types of nanomaterials, including metal nanoparticles (NPs), metal oxides, metal–organic frameworks (MOFs), , conducting polymers, , molecularly imprinted polymers, , carbon, and composite materials, are potential candidates for nonenzymatic lactate sensors. Among these materials, metal oxide nanomaterials, especially transition metal oxides, offer several important advantages, such as easy synthesis, high stability, tunable morphology, adjustable porosity, and versatile functionalization.…”