Construction of Uniformly Dispersed Ag Nanoclusters in Nitrogen-Doped Carbon Tubes for Electrochemical Sensing of Tryptophan

An in situ confinement polymerization technology was developed to construct nitrogen-doped carbon tubes (NCT) with a uniform distribution of silver nanoclusters (AgNCs). Specifically, polydopamine (PDA) was utilized as a good stabilizer and carbon precursor by using curcumin as a template to induce the self-polymerization of dopamine in the presence of Ag+. Then, the AgNC@NCT materials were formed by template removal and subsequent carbonization. The prepared AgNC@NCT materials exhibited excellent stability, catalytic activity, and electrochemical properties due to their high carbonization and silver content. The AgNC@NCT-modified electrode had strong catalytic oxidation activity, specific surface area, and charge transfer efficiency for the detection of d-tryptophan (d-Trp). The constructed electrochemical sensor demonstrated a good linear range (0.1–100 μM) with a low detection limit (0.009 μM) for d-Trp detection. The sensor also had excellent selectivity, high stability, and repeatability. More importantly, it could be used for the evaluation of d-Trp levels in human serum with high accuracy. This method provided a strategy for the detection of d-Trp in biological samples, which had a good application prospect in daily clinical tests.