Assembly-Induced
Emission of Copper Nanoclusters:
Revealing the Sensing Mechanism for Detection of Volatile Basic Nitrogen
in Seafood Freshness On-Site Monitoring
posted on 2024-01-23, 18:36authored byChenyue Zhou, Da-Wen Sun, Ji Ma, Anjun Qin, Ben Zhong Tang, Xiao-Ru Lin, Shi-Lin Cao
Total volatile basic
nitrogen (TVB-N) is a vital indicator
for
assessing seafood freshness and edibility. Rapid on-site detection
of volatile basic nitrogen (VBN) is of significant importance for
food safety monitoring. In this study, highly luminescent self-assembled
copper nanoclusters (Cu NCs@p-MBA), synthesized using p-mercaptobenzoic acid (p-MBA) as the ligand,
were utilized for the sensitive detection of VBNs. Under acidic conditions,
Cu NCs@p-MBA formed compact and well-organized nanosheets
through noncovalent interactions, accompanied by intense orange fluorescence
emission (651 nm). The benzene carboxylic acid part of Cu NCs@p-MBA provided the driving force for supramolecular assembly
and exhibited a strong affinity for amines, particularly low-molecular-weight
amines such as ammonia (NH3) and trimethylamine (TMA).
The quantitative determination of NH3 and TMA showed the
detection limits as low as 0.33 and 0.81 ppm, respectively. Cu NCs@p-MBA also demonstrated good responsiveness to putrescine
and histamine. Through density functional theory (DFT) calculations
and molecular dynamics (MD) simulations, the precise atomic structure,
assembly structure, luminescent properties, and reaction processes
of Cu NCs@p-MBA were studied, revealing the sensing
mechanism of Cu NCs@p-MBA for highly sensitive detection
of VBNs. Based on the self-assembled Cu NCs@p-MBA
nanosheets, portable fluorescent labels were developed for semiquantitative,
visual, and real-time monitoring of seafood freshness. Therefore,
this study exemplified the high sensitivity of self-assembly induced
emission (SAIE)-type Cu NCs@p-MBA for VBNs sensing,
offering an efficient solution for on-site monitoring of seafood freshness.