Exploration of nisin-directed gold nanoclusters employed for detecting thiourea and the sensing mechanism

In this study, we successfully synthesized the red-fluorescence gold nanoclusters (AuNCs@nisin) while employing nisin as the template, and AuNCs@nisin showed the uniform particle size of around 3.5 ± 0.5 nm, and the corresponding excitation and emission wavelengths were 493 nm and 644 nm, respectively. Meanwhile, AuNCs@nisin was mainly composed by the elements of C, N, O, Au as well as S, and it was equipped with the functional groups of hydroxyl and amino. Significantly, the fluorescence of AuNCs@nisin showed the obvious response to thiourea based on the interaction between the metal core of AuNCs@nisin and thiourea, thus leading to the formation of Au-S bond and affecting the fluorescence intensity of AuNCs@nisin. Consequently, we achieved to establishing the detection of thiourea by AuNCs@nisin, and the corresponding linear range between the fluorescence intensity of AuNCs@nisin and the concentration of thiourea was 2 mmol/L-4 mol/L with a detection limit of 0.74 μmol/L. Consequently, the prepared AuNCs@nisin exhibited the potential of serving as a fluorescent probe for determining thiourea.