Label-free approach for electrochemical ferritin sensing using biosurfactant stabilized tungsten disulfide quantum dots.

A novel approach for the synthesis of biosurfactant stabilized/functionalized tungsten disulfide (WS-B) quantum dots (QDs) and its application for ferritin immunosensor is reported. These 2-D layered material derived quantum dots are synthesized via one-step liquid exfoliation method and biosurfactant was used as a functionalization and stability providing moiety. The biosurfactant provided a clean and green method for both the synthesis and in-situ functionalization of the QDs. Exhaustive characterization using analytical techniques was done to study various aspects of the synthesized quantum dots. The functionalized quantum dots (WS-B QDs) were further explored for their possible application as an electroactive platform. For this, the working area of commercially available screen-printed electrodes (SPE) was functionalized with these WS-B QDs to construct a sensor platform. This sensor platform was then used for fabrication of ferritin immunosensor, using ferritin specific antibodies. Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques were used for electrochemical immunosensing of ferritin. Though, the achieved linear range for ferritin detection (10-1500 ng mL) is same with both the techniques but regression coefficient and limit of detection are better in differential pulse voltammetry. The limit of detection was found to be 3.800 ng mL in DPV and 6.048 ng mL in CV. The immunosensor is highly selective, reproducible and is stable for about 60 days.