A portable microfluidic device-based Fe<sub>3</sub>O<sub>4</sub>–urease nanoprobe-enhanced colorimetric sensor for the detection of heavy metals in fish tissue
Krishna Kumari Swain, R. Balasubramaniam, Sunil Bhand
Abstract
Krishna Kumari Swaina, R. Balasubramaniamb & Sunil Bhanda*a Biosensor Lab, Department of Chemistry, BITS Pilani KK Birla Goa Campus, South Goa, India; b Precision Machining Section, Precision Engineering Division, Bhabha Atomic Research Centre, Mumbai, IndiaSupplemental data for this article is available online at http://dx.doi.org/10.1080/10826068.2020.1780611CONTACT Sunil Bhand [email protected] Biosensor Lab, Department of Chemistry, BITS Pilani KK Birla Goa Campus, NH17B Zuarinagar, South Goa 403726, India.AbstractA portable microfluidic device with highly sensitive enzyme nanoprobe (Fe3O4 MNPs–urease, average size 34.6 nm) was demonstrated for the analysis of heavy metals ions (Hg2+, Cd2+ and Pb2+) in fish gill and muscle tissue. The immobilized urease nanoprobe (Km = 0.05 mM) exhibited twofold sensitivity over the free enzyme assay (apparent Km = 0.1 mM). The nanoprobe was characterized using SEM, EDAX, PSA and FT-IR. The inhibition measurements were carried out for individual as well as the mixture of metal ions (CRM standards of 9 elements (CRMmix-9)). The lower limit of quantification (LOQ) (0.5, 0.1, and 0.1 ng L−1 for Hg2+, Cd2+, and Pb2+) and lower limit of detection (LOD) was achieved at 0.1 ng L−1 with sensitivity 8–14% per decade for Hg2+, Cd2+, and Pb2+ ions. A visual result can be observed by the naked eye through the microfluidic device as well as with 96 transparent microwell plates. The order of relative inhibition was found to be CRMmix-9 > (Hg2+ + Cd2+ + Pb2+) > (Cd2+ + Pb2+) > (Pb2+ + Hg2+) > (Hg2+ + Cd2+) > Pb2+ > Cd2+ > Hg2+, respectively. The recovery % in fish tissues were found to be 88–98% for Hg2+, Cd2+ and Pb2+ ions.