Aiming at the shortcomings of high cost and time-consumption in traditional liquid chromatography, an effective surface enhanced Raman scattering (SERS)-based trace detection method has been proposed to quantitatively identify the active component of traditional Chinese medicine. In this paper, a high-performance and versatile SERS platform based on Ag nanoparticles (NPs) self-assembly Ag-anodized aluminium (Ag NPs-Ag-AAO) nanoarray was fabricated by controllable physico-chemical preparation technology. The results indicated that the electromagnetic field enhancement effect was sharply strengthened as Ag NPs assembled, and the experimental enhancement factor (EEF) value was calculated to be 1.0083 × 10⁶. This novel Ag NPs-Ag-AAO nanoarray with substantial “hot spots” exhibited high SERS signal reproducibility, with the relative standard deviation (RSD) value at less than 2.23%. More importantly, this SERS platform was applied to detect active component Baicalein in Scutellaria baicalensis, and the limit of detection (LOD) was located at 10 fg/mL. Therefore, this Ag NPs-Ag-AAO nanoarray with high sensitivity, strong Raman signal reproducibility and reliable practicability has broad application prospects in the rapid detection of trace substances in the active components of traditional Chinese medicine and is expected to be popularized.

TiO₂ films exhibiting structural colors were successfully prepared using one-step electrochemical oxidation. Results of theoretical analyses and digital simulations revealed that the structural color of a TiO₂ thin film could be regulated by adjusting oxidation voltage and oxidation time with different oxidation voltages leading to changes in structural color annulus number. At a low oxidation voltage, each thin film exhibited a single structural color, while thin films with different structural colors were obtained by varying the oxidation time. By contrast, at a higher oxidation voltage, each film exhibited iridescent and circular structural color patterns associated with symmetrical decreases in surface oxidation current density along radial lines emanating from the film center to its outer edges. TiO₂ films exhibiting iridescent structural colorations have broad application prospects in industrial fields related to photocatalysis and photovoltaic cells.

For this study, porous anodic alumina thin films with annular structural colors were fabricated in a phosphoric acid electrolyte by the one-step oxidation of an aluminum (Al) sheet. In this case, small carbon balls were used as the cathode and an Al sheet used as the anode, with the distance between cathode and anode remaining adjustable. Electron microscopy shows that the different parts of films are different in microstructure. Results additionally reveal that the depth and aperture of nano-holes diminished symmetrically outward from the center of the films. It is possible to control ring density by changing the oxidation time and voltage. These experimental results, conducted using point electrode, are consistent with a theoretical study of the oxidation process and formation mechanism of anodic alumina thin films with annular structural colors.

A high-efficiency surface-enhanced Raman scattering (SERS) detection method with ultra-high sensitivity has been widely applied in drug component detection to optimize the product quality verification standards. Herein, a controllable strategy of sputtering Ag nanoislands on carbon fiber (C-fiber) via magnetron sputtering technology was proposed to fabricate a versatile Ag-C-fiber SERS active substrate. A wide range of multi-level electromagnetic enhancement “hot spots” distributed on Ag-C-fiber nanostructures can efficiently amplify Raman signals and the experimental enhancement factor (EEF) value was 3.871 × 10⁶. Furthermore, substantial “hot spots” of large-scale distribution guaranteed the superior reproducibility of Raman signal with relative standard deviation (RSD) values less than 12.97%. Limit of detection (LOD) results indicated that when crystal violet (CV) is employed as probe molecule, the LOD was located at 1 × 10⁻¹³ M. By virtue of ultra-sensitivity and good flexibility of the Ag-C-fiber nanotemplate, Raman signals of two kinds of antiepileptic drugs called levetiracetam and sodium valproate were successfully obtained using an SERS-based spectral method. The Ag-C-fiber SERS detection platform demonstrated a good linear response (R² = 0.97486) in sensing sodium valproate concentrations in the range of 1 × 10³ ng/μL⁻¹–1 ng/μL. We believe that this reliable strategy has potential application for trace detection and rapid screening of antiepileptic drugs in the clinic.