Ni Nanoparticles Embedded Ti(3)C(2)T(x)-MXene Nanoarchitectures for Electrochemical Sensing of Methylmalonic Acid

MXenes-Ti(3)C(2)T(x), based on their versatile surface characteristics, has rapidly advanced as an interactive substrate to develop electrochemical sensors for clinical applications. Herein, Ni embedded Ti(3)C(2)T(x) (MX−Ni) composites were prepared using a self-assembly approach where Ti(3)C(2)T(x) sheets served as an interactive conductive substrate as well as a protective layer to nickel nanoparticles (Ni NPs), preventing their surface oxidation and aggregation. The composite displayed a cluster-like morphology with an intimate interfacial arrangement between Ni, Ti(3)C(2)T(x) and Ti(3)C(2)T(x)-derived TiO(2). The configuration of MX−Ni into an electrochemical sensor realized a robust cathodic reduction current against methylmalonic acid (MMA), a biomarker to vitamin B12 deficiency. The synergism of Ni NPs strong redox characteristics with conductive Ti(3)C(2)T(x) enabled sensitive signal output in wide detection ranges of 0.001 to 0.003 µM and 0.0035 to 0.017 µM and a detection sensitivity down to 0.12 pM of MMA. Importantly, the sensor demonstrated high signal reproducibility and excellent operational capabilities for MMA in a complex biological matrix such as human urine samples.