A smartphone-assisted microarray immunosensor coupled with GO-based multi-stage signal amplification strategy for high-sensitivity detection of okadaic acid

Okadaic acid (OA) is one of the main virulence factors of diarrheal shellfish toxins (DSP), which can cause acute carcinogenic or teratogenic effects after ingestion of contaminated shellfish. Therefore, high-sensitivity and fast detection of OA is a key to preventing the occurrence of safety accidents. In this paper, we effectively established a smartphone-assisted microarray immunosensor combined with an indirect competitive ELISA (iELISA) for quantitative colorimetric detection of OA. To further improve the detection sensitivity and match the smartphone imaging, a novel graphene oxide (GO) composite probe was developed to realize the multi-stage signal ampli-fication. The system exhibited a wide linear range for the detection of OA (0.02-33.6 ng & BULL;mL(-1)) with low detection limit of 0.02 ng & BULL;mL(-1). The recovery of OA in spiked shellfish samples was in the range of 80%- 103.5%, which indicates the good applicability of this biosensor. The whole detection system has advantages of simplicity, low cost, high sensitivity and portability, which is expected to be a powerful alternative tool for on-site detecting and early warning of the pollution of marine products.

Automated summary

In this study, a smartphone-assisted microarray immunosensor combined with an indirect competitive ELISA was developed for quantitative colorimetric detection of Okadaic acid (OA). A novel graphene oxide composite probe was used to improve the detection sensitivity. The system showed a wide linear range for OA detection with low detection limit and good applicability in shellfish samples.