Label free electrochemical sensors for Pb(II) detection based on hemicellulose extracted from Opuntia Ficus Indica...

We aim to develop an electrochemical sensor for a divalent metal ion (lead II), a highly toxic water contaminant. We explore a sensor formed with a hemicellulose polysaccharide extracted from the Opuntia Ficus Indica cactus associated with agarose as a sensitive layer deposited on a gold electrode. This sensor combines the functional groups of hemicellulose that could form a complex with metal ions and agarose with gelling properties to form a stable membrane. The sensor demonstrated a loading ability of Pb²⁺, with higher affinity compared to other metal ions such as Hg²⁺, Ni^2+, and Cu²⁺, thanks to the chemical structure of hemicellulose. The detection was measured by square wave voltammetry based on a well-defined redox peak of the metal ions. The sensor shows high sensitivity towards Pb²⁺ with a detection limit of 1.3 fM. The application in river and sea water using the standard addition method for lead detection was studied.