Hollow-like three-dimensional structure of methyl orange-delaminated TiC MXene nanocomposite for high-performance electrochemical sensing of tryptophan.

Tryptophan(Trp) is being explored as a potential biomarker for various diseases associated with decreased tryptophan levels; however, metabolomic methods are expensive and time-consuming and require extensive sample analysis, making them urgently needed for trace detection. To exploit the properties of TiC MXenes a rational porous methyl orange (MO)-delaminated TiC MXene was prepared via a facile mixing process for the electrocatalytic oxidation of Trp. The hollow-like 3D structure with a more open structure and the synergistic effect of MO and conductive TiC MXene enhanced its electrochemical catalytic capability toward Trp biosensing. More importantly, MO can stabilize TiC MXene nanosheets through noncovalent π-π interactions and hydrogen bonding. Compared with covalent attachment, these non-covalent interactions preserve the electronic conductivity of the TiC MXene nanosheets. Finally, the addition of MO-derived nitrogen (N) and sulfur (S) atoms to TiC MXene enhanced the electronegativity and improved its affinity for specific molecules, resulting in high-performance electrocatalytic activity. The proposed biosensor exhibited a wide linear response in concentration ranges of 0.01-0.3 µM and 0.5-120 µM, with a low detection limit of 15 nM for tryptophan detection, and high anti-interference ability in complex media of human urine and egg white matrices. The exceptional abilities of the MO/TiC nanocatalyst make it a promising electrode material for the detection of important biomolecules.