Rapid and ultralow level SERS detection of ethylparaben using silver nanoprisms functionalized sea urchin-like Zinc oxide nanorod arrays for food safety analysis

Abstract

Surface enhanced Raman spectroscopy (SERS) offers a tremendous opportunity to sense food additives in a fast, flexible and ultrasensitive mode. In the present study, we have designed silver nanoprism (AgNPr) functionalized Zinc Oxide (ZnO) hetero architectures for SERS sensing of food preservatives such as ethylparaben (EP). ZnO nanorods (NRs) were found to be formed which organized into sea urchin-like morphology via a facile hydrothermal process. While varying the growth time from 3 to 72 h, the nanorod length was found to be enhanced from 500 to 1900 nm range. The effect of morphology of as-fabricated substrates was well correlated with absorption and vibrational modes. Moreover, silver nanoprisms with peculiar triangular morphology with a size range of 20–80 nm were synthesized for functionalizing ZnO arrays; whose incorporation was further confirmed by EDS and XPS analysis. SERS studies demonstrated that AgNPr/ZnO NRs assembly exhibited synergistic Raman signal enhancement, which was modulated by the length of the nanorods. The highest SERS activity was exhibited by substrates with ∼1500 nm nanorod length. The reproducibility and reusability of optimized AgNPr/ZnO NRs substrates were demonstrated as well. The developed sensor exhibited highly specific real-time sensing of EP with sensitivity down to pico-molar levels; could be considered a good candidate for rapid, in situ identification of food preservatives for food safety applications. • Hierarchical zinc oxide-silver nanoprism arrays were designed as SERS sensors. • Morphological properties of sensor was well correlated with SERS performance. • Nanorod lengths of ∼1500 nm demonstrated highest signal enhancement. • Food additive like ethylparaben (EP) was detected down to pico-molar levels. • The optical sensing of EP was evidenced with high sensitivity and reusability.