Polydopamine-modified 3D ordered micropillar arrays for uniform and dense immobilization of silver nanoflowers toward ultrasensitive SERS detection of multiple pollutants

Surface-enhanced Raman scattering (SERS) has emerged as a powerful analytical technique for ultrasensitive and rapid detection. However, the performance of SERS substrates largely depends on their ability to generate intense localized electromagnetic fields at nanoscale hot spots, while simultaneously achieving high sensitivity and signal reproducibility remains a major challenge. In this work, a highly ordered SU-8 micropillar array was fabricated by Ultraviolet Lithography(UL), followed by biomimetic modification with polydopamine (PDA) to achieve the uniform immobilization of silver nanoflowers (AgNFs). The resulting three-dimensional (3D) AgNFs/PDA/SU-8 micropillar SERS substrate integrates the structural advantages of the 3D architecture, the abundant electromagnetic hot spots and physical enrichment effect generated by densely packed AgNFs, and the interfacial regulation provided by PDA, thereby synergistically enhancing the SERS performance. The substrate exhibited an enhancement factor(EF) of 2.16 × 10 9 for Rhodamine 6G (R6G), with an experimental limit of detection as low as 1 × 10 −14 M (S/N = 3) and a relative standard deviation below 8.30%. Furthermore, the limits of detection for enrofloxacin (ENR), clothianidin (CLO), and 100 and 800 nm polystyrene (PS) particles in seawater reached 1 × 10 −13  M, 1 × 10 −14  M, 2.5 μg mL −1 , and 0.6 mg mL −1 , respectively. Simultaneous detection of multiple contaminants was also successfully achieved in complex food matrices, including mineral water, milk, and liquor. This work provides an effective strategy for constructing high-performance 3D SERS substrates and demonstrates their promising potential for food safety monitoring and aquatic environmental analysis.