Development of a Ti₃C₂ MXene-AgNPs-based SERS platform for ionophore-based ion-selective detection

Surface-enhanced Raman spectroscopy (SERS) has advanced as a crucial analytical technology, benefiting numerous fields with its high sensitivity and versatility. However, its application in detecting ions has been underexplored. In this study, we developed a novel SERS sensing platform for ion detection by creating a Ti₃C₂ Mxene-AgNPs substrate and integrating it with the ionophore-based ion-selective sensing framework. The Ti₃C₂ Mxene-AgNPs substrate was successfully prepared via electrodeposition on conductive glass, achieving an enhancement factor of 1.86 × 10⁶ and demonstrating good signal repeatability (RSD = 8.17 %). The AgNPs ensure amplified and stable SERS activity, while large surface area of the MXene nanosheets offers a significant advantage for AgNPs and sensing chemical loading. The Ti₃C₂ Mxene-AgNPs SERS substrate enables ionophore-based ion-selective sensing with exceptional selectivity and high sensitivity for target ion detection, eliminating the need for plasticizers. A selective turn-on SERS response of this platform to various concentrations of K⁺, Na⁺, and Ca²⁺ was exemplified in this study, further revealing its excellent generalizability. Moreover, the applicability of this method was preliminarily demonstrated by its successful application in determining Na⁺ in human blood serum and environmental water samples (river and estuary). The successful integration of the versatile and rapidly progressing SERS technique, enabled by the Ti₃C₂ Mxene-AgNPs substrate, for electrolyte cation detection offers a promising avenue for enhancing current ion detection capabilities in biological and environmental samples.