Superhydrophobic-Superhydrophilic Hybrid Surface with Highly Ordered Tip-Capped Nanopore Arrays for Surface-Enhanced Raman Scattering Spectroscopy.

The designed superhydrophobic-superhydrophilic hybrid surface (SSHS) with highly ordered tip-capped nanopore arrays can be used as an intelligent and fast platform to realize different analyte solutions with different concentrations to be detected at the same time by surface-enhanced Raman spectroscopy. This surface is fabricated in a large area by a facile and low-cost method of programmed multistep anodization of aluminum and pore widening process followed by selective chemical modification. The highly ordered tip-capped nanopore arrays can induce the highly sensitive and reproducible Raman signal, whose enhanced factor for rhodamine 6G (R6G) at 1358 cm-1 is 4.46 × 106. The superhydrophobic-superhydrophilic hybrid property can realize the homogeneous distribution of the concentrated analyte in a droplet at the fixed place, which can avoid the diffusion-limit problem and further enhance the Raman signal. Surface-enhanced Raman spectroscopy of dried droplets with different concentrations of R6G or thiram is tested on SSHS, which show good reproducibility. The detection limits of R6G and thiram on SSHS are 10-10 and 10-7 M in 50 μL droplets, respectively. Due to the industrial compatibility of the fabrication technique, this smart surface has the potential to evolve into a general platform to develop various advanced chemical and biological sensors.