Advances in the Detection of Toxic Algae Using Electrochemical Biosensors.

Linda K Medlin,José M M Pingarrón,Gerardo Mengs,Maria Gamella,Susana Campuzano,Verónica Serafín

doi:10.3390/bios10120207

Abstract

Harmful algal blooms (HABs) are more frequent as climate changes and tropical toxic species move northward, especially along the Iberian Peninsula, a rich aquaculture area. Monitoring programs, detecting the presence of toxic algae before they bloom, are of paramount importance to protect ecosystems, aquaculture, human health and local economies. Rapid, reliable species identification methods using molecular barcodes coupled to biosensor detection tools have received increasing attention as an alternative to the legally required but impractical microscopic counting-based techniques. Our electrochemical detection system has improved, moving from conventional sandwich hybridization protocols using different redox mediators and signal probes with different labels to a novel strategy involving the recognition of RNA heteroduplexes by antibodies further labelled with bacterial antibody binding proteins conjugated with multiple enzyme molecules. Each change has increased sensitivity. A 150-fold signal increase has been produced with our newest protocol using magnetic microbeads (MBs) and amperometric detection at screen-printed carbon electrodes (SPCEs) to detect the target RNA of toxic species. We can detect as few as 10 cells L−1 for some species by using a fast (~2 h), simple (PCR-free) and cheap methodology (~2 EUR/determination) that will allow this methodology to be integrated into easy-to-use portable systems.

Highlights

In the last century, human poisonings by harmful algae have occurred most often because regular monitoring programs did not exist worldwide
We present here probes for the benthic dinoflagellate species belonging to Gambierdiscus, Ostreopsis, Coolia and Prorocentrum lima, which are species moving into European waters as climate changes
The first species has been reported from Cape Verde (Emertox, unpubl.) and the last from the Iberian Peninsula [23]

Summary

Introduction

Human poisonings by harmful algae have occurred most often because regular monitoring programs did not exist worldwide. Harmful algal blooms (HABs) are becoming more frequent as climate changes, with tropical toxic species moving northward. They are not yet listed among the toxins required for monitoring. We present here probes for the benthic dinoflagellate species belonging to Gambierdiscus, Ostreopsis, Coolia and Prorocentrum lima, which are species moving into European waters as climate changes. These probes are not included in the MIDTAL microarray for toxic algae. The variation in the cathodic current, attributed to the enzymatic reduction of H2 O2 mediated by HQ is proportional to the concentration of the target DNA/RNA and proportional to the number of target cells in the water, our early warning system

Material and Methods

Results and Discussion

Conclusions