Automated lab-on-chip for the specific detection of invasive species through environmental DNA

Abstract

The ability to detect nucleic acid sequences is revolutionizing the fast identification of specific organisms, particularly with Lab-on-a-chip systems. However, these often rely on complex processes, skilled personnel, and external control devices which limits automation. To address this, we present an automated, portable, and easy-to-fabricate lab-on-chip that combines enzyme-assisted DNA signal amplification and optical detection for in-situ monitoring of zebra mussel invasive species in the environment. Zebra mussels DNA triggers enzyme-assisted signal amplification through hybridization, leading to a quantitative colorimetric response. The sensing performance exhibited enhanced sensitivity when increasing AuNPs diameter from 23.3 ± 1.6 to 67.4 ± 2.0 nm. Quantitative colorimetric approaches displayed an LoD of 0.5 pM, 19-fold increase in sensitivity when compared to naked eye. The system enabled to discriminate single nucleotide polymorphism (SNP) for concentrations from 130 pM and to successfully analyse Zebra mussel samples from the Guadalquivir River. Experiments were conducted by the user and an automated device. The accuracy was tested with a 60 pM sample which was pre-treated externally and analysed by the automated system resulting in relative error of 16.8% and 13.4%, respectively. The automated system reduced the analysis time by 1 h and 20 min, great advantage for in-situ analysis.