Sensing of Zn(II) and nitroaromatics using salicyclaldehyde conjugated lysozyme-stabilized fluorescent gold nanoclusters

• Published in: Microchemical journal 2019-12, Vol.151, p.104227, Article 104227
• Main Authors: Bhardwaj, Vinita, Anand, Thangaraj, Choi, Heung-Jin, Sahoo, Suban K.
• Format: Article
• Language: English
• Subjects: Fluorescent gold nanoclusters; Fluorescent sensors; para-Nitrophenol; Picric acid; Zn(II)
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2019.104227

This manuscript presents new applications of the red-emitting lysozyme-stabilized gold nanoclusters (Lyso-AuNCs) in the field of fluorescent sensing. With the addition of salicylaldehyde (SA) to the solution of Lyso-AuNCs, the red-emission turned immediately to yellow, and the emission band at 650 nm was blue-shifted and enhanced significantly at 498 nm due to the formation of imine linkage between the –CHO group of SA and the –NH2 groups of the lysozyme coated on the surface of AuNCs. The nano-assembly SA conjugated Lyso-AuNCs (SA_Lyso-AuNCs) was applied as a nanoprobe for the fluorescent detection of metal ions and nitroaromatics. With the addition of Zn2+, the probe SA_Lyso-AuNCs showed selective turn-on fluorescence enhancement at 452 nm due to the complexation-induced aggregation of the nanoclusters, and the titration experiment inferred that the Zn2+ ions can be detected down to 1.37 × 10−7 M. In contrast, when the nitroaromatics were added to the probe SA_Lyso-AuNCs, selective fluorescence quenching of the probe was observed at 650 nm and 498 nm in the presence of picric acid (PA) and para-nitrophenol (p-NP). The limit of detection of nitroaromatics PA and p-NP can be detected down to 2.90 × 10−7 M and 3.59 × 10−7 M, respectively. Finally, the practical utility of the probe SA_Lyso-AuNCs was validated by quantifying PA and p-NP in the real water samples. •The red-emission of Lyso-AuNCs turned immediately to yellow upon interaction with salicylaldehyde (SA).•The nano-assembly SA conjugated Lyso-AuNCs (SA_Lyso-AuNCs) was applied as a nanoprobe.•SA_Lyso-AuNCs showed selective turn-on fluorescence enhancement at 452 nm in the presence of Zn2+.•SA_Lyso-AuNCs showed selective turn-on fluorescence at 650 nm and 498 nm in the presence of picric acid and para-nitrophenol.