Electrochemical Approach for the Synthesis of Ultrasmall Cu Clusters and Their Application in the Detection of Endotoxin.

Ultrasmall metal nanoclusters are attractive for their size-dependent optical and electrochemical properties. Here, blue-emitting copper clusters stabilized with cetyltrimethylammonium bromide (CTAB) are synthesized using an electrochemical approach. The electrospray ionization (ESI) analysis reveals that the cluster has 13 copper atoms in the core. The clusters are then used for the electrochemical detection of endotoxin─a bacterial toxin in Gram-negative bacteria. Differential pulse voltammetry (DPV) is used to detect endotoxins with high selectivity and sensitivity. It shows a lower detection limit of 100 ag mL with a linear range of 100 ag mL to 10 ng mL. The sensor is efficient for detecting endotoxins from human blood serum samples.