Hydrogen-bonding recognition-induced aggregation of gold nanoparticles for the determination of the migration of melamine monomers using dynamic light scattering

• The p-DNA modified GNPs were synthesized to recognize melamine.
• The strategy was developed in the measurement of MMMQ by DLS technique.
• The influence of four solvents, temperature, and time on MMMQ was investigated.
• The method provides good linearity (R ≥ 0.9970) and high sensitivity (2 μg  L−1).

The migration of melamine monomers from food contact materials has aroused particular attention since the 2008 melamine-tainted milk scandal in China. However, the determination of melamine monomer’s migratory quantity (MMMQ) has remained an open question because of the complex sample pretreatment and the low sensitivity. Based on the hydrogen bonding interaction between DNA thymine and melamine, this paper described a simple and rapid method focusing on the measurement of MMMQ from melamine tableware by gold nanoparticles (GNPs) and dynamic light scattering (DLS). With the presence of probe DNA (p-DNA), the GNPs were stable in NaCl solution (0.06 M), whereas they became aggregated when the p-DNA hybridized with melamine. The change in the hydrodynamic diameter of GNPs could be detected by DLS technology. Under the optimal conditions, the average diameter increased linearly with the concentration of melamine over the range from 5.0 to 320.0 μg L−1, and showed a detection limit of 2.0 μg  L−1 (3σ/slope). The MMMQ was investigated within a range from 6.00 × 10−4 to 2.58 × 10−1 mg dm−2 (n ≥ 3) in four different food simulants at different temperatures and time points. The results suggest that the DLS method has great potential in the analysis of the migration of melamine monomers.

Melamine (M) can hybridize with thymine (T) through the hydrogen-bonding recognition. The combination of melamine with the p-DNA (containing 6 T) modified GNPs induces the aggregation of GNPs. The change in the size of GNPs can be distinguished by DLS technology with high sensitivity.Figure optionsDownload as PowerPoint slide