In a paper published in Chemistry - A European Journal, Prof. YANG Liangbao's team of Institute of Intelligent Machines, Hefei Institutes of Physical Science, proposed a rapid and effective strategy to self-assemble gold nanoparticles at liquid/liquid interface and to acquire integrated interfacial film.

Liquid interfacial self-assembly of metal nanoparticles holds great promise for its various applications such as tunable optical devices, plasmonics, sensors, and catalysis. However, construction of large area ordered anisotropic nanoparticles monolayer and acquisition of self-assembled interface film are still significant challenges.

Looking at this, the team recently developed a rapid and valid method to fabricate large-scale close packed nanomaterials at the cyclohexane/water interface in which Au nanorods (AuNRs) self-assembled into densely packed two dimensional (2D) arrays by regulating the surface ligand and suitable inducer.

More importantly, they exhibit a general and facile novel technique to transfer interfacial monolayer through a designed reaction cell in situ linked a microfluidic chip, and then the self-assembled nanofilm could automatically settle on the substrate and directly detected on the reaction cell in situ by portable Raman spectrometer.

Moreover, close-packed monolayer of self-assembled AuNRs provided massive efficient hotspots to create great surface-enhanced Raman scattering (SERS) enhancement, providing high sensitivity and reproducibility as the SERS-active substrate.

Furthermore, this strategy was exploited to detect drug molecules in human urine for cyclohexane extracted targets acting as oil phase to form oil/water interface.

Universal platform, handy tool and fast pretreatment confirmed a good capability for drug detection in complicated biological system, even showed great promise in the issue of rapid, credible and on-spot detection for drug crimes.

This work was supported by the National Science Foundation of China, Special Financial Grant from the China Postdoctoral Science Foundation, the Anhui Natural Science Foundation, the Sci-tech Police Project of Anhui Province, the CASHIPS Director’s Fund and the China Postdoctoral Science Foundation.

Scheme. Self-assembly of AuNRs at liquid interface. Schematic illustrations and optical images of the A) ligand exchange of AuNRs, B) acquired interfacial film, C) natural deposition strategy to obtain the self-assembled film. (Image by MAO Mei)