Anisotropic Growth of Amorphous Structures via Interfacial Self-Assembly of Hydrophobic Gold Nanoparticles for Reliable and Accurate Detection of Pesticide Residues

Recently, amorphous nanomaterials with unique structural features that crystalline materials may lack such as long-range atomic disorder have attracted great attention due to their outstanding surface-enhanced Raman scattering (SERS) properties. Herein, uniform hydrophobic gold nanoparticles (4.4 ± 0.95 nm) have been fabricated for realizing dodecylamine-assisted interfacial self-assembly at the air-water interface of Langmuir-Blodgett (LB) instruments for producing disordered amorphous disc superstructures, with their diameter ranging from ∼200 to ∼700 nm and height within 10-15 nm. When the surface tension of the air-water interface is increased from 0 to 10 and 20 mN/m, they can be linked together to form disc chains and networks, respectively. Interestingly, in the absence of free dodecylamine, these dodecylamine-stabilized hydrophobic gold nanoparticles will form highly ordered hexagonal close-packed monolayer films. Significantly, these amorphous disk superstructures possess better SERS performance than the ordered monolayer films. Further studies suggest that amorphous disc superstructures prepared for SERS sensors have advantages of low limit of detection (0.032 nM), excellent long-term stability, and a wide linear range (0.01-1000.0 nM) for detecting acetamiprid. Furthermore, they display splendid SERS performance for rapid determination of acetamiprid residues on the surface of apples, showing their ability for reliable and accurate detection of pesticide residues in real samples. Our research provides an effective approach for preparing amorphous structures via interfacial self-assembly, which reveals promising application prospects for detecting pesticide residues in real food samples.