Highly Specific Detection of Sc3+ in Rare Earth Elements Using a DNA-Functionalized, Silica Nanowire-Filled Micropipette

Scandium (Sc), as a critical rare earth element (REE), holds significant application value in advanced manufacturing, energy materials, catalysis, and other fields. However, due to the common coexistence of Sc with light and heavy REEs, which exhibit high similarities in ionic radius, valence state, and coordination chemistry, conventional spectrophotometric methods suffer from poor selectivity, making accurate quantification of Sc3+ in complex matrices difficult. In this study, we present a label-free ion sensing platform based on silicon nanowire-modified glass micropipettes (SiNWs@GMP). By incorporating the Sc-1 DNA recognition unit, the platform achieves highly sensitive and selective detection of Sc3+ as well as sequential discrimination between light and heavy REEs. The three-dimensional porous SiNWs network inside the GMP provides abundant immobilization sites for Sc-1 DNA. Under an applied electric field, the specific binding between Sc3+ and Sc-1 DNA modulates ion transport within the channel, generating measurable changes in ionic current. The constructed sensor exhibits a detection concentration range for Sc3+ from 1 pM to 105 pM and a detection limit for Sc3+ as low as 1 pM, which can effectively distinguish Sc3+ from light REEs. Meanwhile, the use of EDTA to selectively suppress interference from coexisting heavy REEs further verifies the high selectivity of Sc-1 DNA. This platform demonstrates good stability, repeatability, and reliability in aqueous environments, highlighting its potential for applications in environmental monitoring and REEs analysis.