Graphene-amplified femtosensitive aptasensing of estradiol, an endocrine disruptor.

We report the construction of a novel electrochemical femtomolar aptasensing APT-ERGO/GCE interface based on the covalent immobilization of 38-mer amine-functionalized (NH2-APT) 17β-estradiol (E2) DNA aptamers on a graphene amplifying platform. Graphene oxide (GO) was synthesized and characterized by using FTIR, UV-vis spectroscopy, XRD spectroscopy, and SEM technique. The strategy for the construction of the E2-aptasensing interface involves in a three-step modification process.

Electrochemical oxidation of dopamine and ascorbic acid at a palladium electrode modified with in situ fabricated iodine-adlayer in alkaline solution.

The self-assembled iodine-adlayer was fabricated at the palladium (Pd) electrode surface throughout a spontaneous oxidative chemisorption of iodide ions contained in an alkaline supporting electrolyte. It enhances the electron transfer kinetics for the oxidation of dopamine (DA) and ascorbic acid (AA) and was important to separate the peak current of both species with a practical potential difference compared with that occurred at the unmodified electrode. The anodic peak currents of both species were linearly increased with their respective concentrations using linear square stripping voltammetry.