Self-supported carbon veil biosensor architecture for voltammetric lactose determination in dairy products

Abstract

The global rise in the prevalence of lactose intolerance has increased the demand for sensitive analytical platforms to monitor low-lactose and lactose-free dairy products. This work details the development of a novel, standalone carbon veil electrode and its application in a cascade biosensing system. The electrode fabrication involves a simple, self-supported design where the carbon veil fibers are localized using a cyanoacrylate dielectric barrier, preventing capillary effects while maintaining a highly accessible 3D macroporous architecture. The carbon veil electrode surface was modified with a supramolecular nanocomposite of silver nanoparticles and pillar[5]arene, followed by the reagent-less immobilization of lactase. Pillar[5]arene facilitates the formation of stable silver nanoparticles and acts as an electron transfer mediator, enhancing the analytical signal through host-guest pre-concentration of the analyte. The biosensor utilizes a dual cascade mechanism: enzymatic hydrolysis of lactose generates glucose, which is then oxidized at the silver nanoparticles catalytic centers. The system exhibited a limit of detection of 3.2 nM and a linear range from 1×10^-8 to 2×10^-4 M. To mitigate matrix effects in complex dairy samples, a preparation protocol involving protein precipitation and centrifugation was developed. Practical performance was evaluated using milk and yogurt samples, employing a sequential measurement strategy and matrix-matched calibration to eliminate interference from endogenous glucose. The developed platform provides a robust, scalable, and cost-effective tool for food quality control and personalized nutrition monitoring.