Ultra-sensitive electrochemical sensor based on molecularly imprinted polydopamine grafted with MWCNT-COOH for tryptophan detection.

An electrochemical sensing platform was developed for the detection of tryptophan (Trp) using a molecularly imprinted polydopamine grafted with functionalized multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE), referred to as MWCNT-COOH/PDA-MIP. Dopamine, as a monomer, underwent self-polymerization in the presence of MWCNT-COOH and the target molecule, Trp, forming a polydopamine network. The synthesized composite was dispersed in an aqueous solvent and cast onto the GCE surface. Trp was then removed from the polymer matrix, creating molecularly imprinted cavities tailored to the size and properties of the target molecule. These cavities enabled the MWCNT-COOH/PDA-MIP to adsorb and recognize Trp with high precision and selectivity. This novel electrochemical sensor achieves an ultra-low detection limit and enhanced specificity for tryptophan detection through the integration of molecularly imprinted polydopamine with functionalized MWCNTs. The morphology and composition of the prepared sensor were analyzed by FT-IR, XRD, EDX, and SEM techniques. Sensor performance was evaluated using differential pulse voltammetry (DPV), revealing a linear response over two concentration ranges: 10 to 10 M and 10 to 10 M. The limit of detection (LOD) and limit of quantification (LOQ) were 4.33 × 10 M and 14.43 × 10 M, respectively. The sensor was successfully applied to measure Trp in real samples, including blood serum and milk, achieving satisfactory results with an average recovery of 97.15%.