  Toxic cyanobacteria blooms have been increasing globally, resulting largely from pollution from modern industrial, agricultural, and domestic activities. Microcystin-LR (MC-LR) and microcystin-RR (MC-RR) are the most common toxins released by cyanobacterial blooms and pose tremendous threat to public health and water safety. Here we report on SERS aptasensors based on the core-satellite assemblies on planar substrate, which on one hand resolved the irreproducible aggregation from the nanoparticles (NPs) in the solution and on the other hand enabled highly sensitive and dual detection of MC-LR and MC-RR. To improve the SERS enhancement of Raman labels, two different NPs composed of successive layers of Au core-SERS label-silver shell-gold shell (Au@label@Ag@Au NPs) with two distinct SERS labels were rationally designed. Since the spectral bands associated with the two SERS labels are distinct, both targets can be sensed simultaneously in a single assay platform. Also, a bottom-up templating strategy based on block copolymer (BCP) brush-like nanolayer was employed to fabricate large-scale and reproducible SERS-active silicon substrates covered with Au nanoflowers (AuNFs). In the presence of MC-LR and MC-RR, the SERS tags were dissociated from the core-satellite assemblies due to the affinity of aptamers with microcystines, resulting in the decrease of SERS signal. The limits of detection are low, at 1.5 pM for MC-LR and 1.3 pM for MC-RR, with excellent recoveries (96% to 105%). The further application of our SERS aptasensors were demonstrated by monitoring the dynamic production of MC-LR in the culture medium from Microcystis aeruginosa cells over 1 week. A highly SERS active and reproducible aptasensor was fabricated for the detection of MC-LR and MC-RR in this wrok and the developed protocol can be applicable to the analysis of other hazardous substances.

SERS detection of microcystin-LR and microcystin-RR with aptamer-driven core-satellite assemblies

ACS Spring Meeting 2021

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