Electrochemical bioplatforms for the simultaneous determination of interleukin (IL)-8 mRNA and IL-8 protein oral cancer biomarkers in raw saliva

The development of electrochemical magnetobiosensors for the simultaneous determination of two biomarkers associated with salivary oral cancer, protein IL-8 and its messenger RNA (IL-8 mRNA) associated, in undiluted human saliva samples is reported in this work. The implemented methodology involves the use of functionalized magnetic beads, specific antibodies against IL-8 protein, a specific hairpin DNA sequence for IL-8 mRNA and amperometric detection at disposable dual screen printed carbon electrodes. This methodology exhibits high sensitivity and selectivity for the target analytes providing detection limits of 0.21 nM for IL-8 mRNA and 72.4 pg mL(-1) (far below the clinical established cut-off of 600 pg mL(-1)) for IL-8 protein in undiluted saliva samples. The dual amperometric magneto-biosensor was applied to the direct determination of both biomarkers in spiked raw saliva samples and to determine the endogenous content of IL-8 protein in saliva samples from 7 healthy individuals. The obtained results were statistically in agreement with those provided by a commercial ELISA kit. (C) 2015 Elsevier B.V. All rights reserved.