Facile in situ synthesis of core-shell MOF@Ag nanoparticles composites on screen-printed electrodes for ultrasensitive SERS detection of polycyclic aromatic hydrocarbons
This paper reports the fabrication of a highly sensitive and reusable substrate for surface-enhanced Raman scattering (SERS) analysis. Core-shell metal-organic framework (MOF; HKUST-1)@Ag nanoparticles (NPs) is prepared on a screen-printing electrode (SPE) via in-situ electrodeposition. The morphology and Ag coverage of core-shell structures can be easily controlled by electrodeposition potential and time without substrate motion. The HKUST-1 (Cu)@Ag composites combine abundant SERS “hot spots” among the high-density Ag NPs and the excellent adsorption performance of MOF, resulting in effective pre-concentration of analytes in close proximity to these “hot spots” and enhancement of SERS sensitivity. The optimized polyhedral HKUST-1@Ag structures exhibits high SERS activity for detecting 4-aminothiophenol at a concentration as low as 5×10-10 M. More importantly, the polyhedral HKUST-1@Ag composites provides high sensitivity for detection of polycyclic aromatic hydrocarbons (PAHs) while preserving the cyclability and selectivity required for reliable quantitative analysis. The method is effective over a wide range of PAHs concentrations (0.5 nM to 0.5 M), with detection limits as low as hundreds of pM. This study offers a new method to tailor the structure of MOF-based SERS substrates for on-site screening or point-of-care application.