Cyclodextrins enable indirect ultrasensitive Raman detection of polychlorinated biphenyls captured by plasmonic bubbles

Capture, detection and removal of persistent organic pollutants (POPs) from water, air and soil are among the hot topics of research in environmental science. Here we report the first example of indirect ultrasensitive detection of polychlorinated biphenyls in water, obtained by analysing the Raman signals of silver-cyclodextrin supracrystals resulting from drying-induced aggregation of plasmonic alginate bubbles. Principal component analysis allowed to extend the detection limit to the level of 1 ng/L, which is two orders of magnitude lower than that requested by current legislation.