Ratiometric SERS detection of polycyclic aromatic hydrocarbons assisted by β-cyclodextrin-modified gold nanoparticles

A surface-enhanced Raman scattering (SERS) method is described for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in the environment efficiently and economically. Detection sensitivity is improved by modifying gold nanoparticles (AuNPs) with 4-mercaptophenylboronic acid (4-MPBA) conjugated to β-cyclodextrin (β-CD) as a new method for ratiometric determination of PAHs in solution. Pyrene (with a Raman band at 580 cm^-1) and anthracene (750 cm^-1) were used as the model analytes, while 4-MPBA (1570 cm^-1) was used as the internal reference to normalize the SERS signals. The intensity ratios of pyrene/4-MPBA increase linearly in the 2 to 10 nM pyrene concentration range, and the intensity ratios of anthracene/4-MPBA increase linearly in the 10 to 100 nM anthracene concentration range. The detection limits are 0.4 nM for pyrene and 4.4 nM for anthracene. This method was applied to the determination of the two analytes in soil sample extracts and the recoveries of pyrene (at levels of 236 ng∙g^-1 and 170 ng∙g^-1) and anthracene (334 ng∙g^-1 and 510 ng∙g^-1) agreed well with the results from GC-MS analyses. The good recovery rates (101.8% and 102.5% for pyrene and 106.4% and 101.7% for anthracene) confirmed the reliability of the method. Graphical abstract Schematic illustration of SERS signal enhancement of pyrene, as an example of polycyclic aromatic hydrocarbons, by β-cyclodextrin modified gold nanoparticles.