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.