Lysozyme Carbo-Gel Integrated Repackable Miniaturized Microextraction Device: A Platform for Rapid Enrichment and Sensitive Detection of Multimetal Ions

Sensing and identifying toxic materials within a complex matrix require development of sensitive and selective analytical devices that can enrich the targeted chemical for analysis. We developed a simple and easy approach to enrich and detect various toxic metal ions from different sample matrices by using a microextraction platform device in combination with inductively coupled plasma mass spectrometry. We fabricated a well-defined carbo-gel nanosphere extractant by combining carboxymethylcellulose as a core template with lysozyme, a structural-directing compact globular protein, using hydrothermal carbonization. This was packed into a 3D-printed miniaturized microextraction device that could be repacked and reused multiple times. The surface chemistry and structural significance of the fabricated extractant were studied using electron microscopy and spectroscopy as well as infrared spectroscopy technologies. The detection limits of the established method for Pb²⁺, Bi³⁺, Ag⁺, Cd²⁺, As³⁺, and Co²⁺ ions were in the range of 0.5-125 ng mL^-1, and the relative standard deviations ranged from 2.1 to 4.6%. High recovery between 90.0 and 103% was observed in complex matrices including real and spiked urine samples and was maintained after six regeneration cycles, where the extractant recovery remained above 85%. The multiplex approach of both extractant and device development can significantly improve selective sensing of toxic or emerging contaminants of concern in complex solutions, which demonstrates its major analytical advancement.