Quantum dot modified interface for electrochemical immunosensing of procalcitonin for the detection of urinary tract infection.

An electrochemical immunoelectrode is fabricated and investigated for quantification of the Procalcitonin (PCT), a protein over expressed in urinary tract infection (UTI). The sensor electrode is prepared by self assembling the conjugate of Zinc sulfide capped Cadmium selenide quantum dots (QD) and PCT specific monoclonal antibody (MAb) over the indium-tin-oxide (ITO) coated glass substrate. The presence of QD in the conjugate is found to provide more electroactive surface area and improved electron transfer kinetics and diffusion coefficient to the immunoelectrode. The electrochemical characteristics of this immunoelectrode towards synthetic PCT sample reveal specificity among the pool of various analytes. The sensing characteristics reveal that the sensor can potentially detect PCT over a concentration of 0.21 ng/mL which is above pathological range in healthy person. However, in absence of QD, the detection range lies in between 0.1 μg/mL to 10 μg/mL, which is far above the expressed concentration of PCT in UTI. Under optimal conditions, the QD based immunoelectrode exhibited good calibration range from 1 ng/ml to 10 μg/mL.