Electrochemical aptasensor based on black phosphorus-porous graphene nanocomposites for high-performance detection of Hg2+

A novel approach was developed to fabricate a label-free electrochemical aptasensor for specific detection of mercury ions (Hg2+). This involved modifying polylysine (PLL)-coated black phosphorus-porous graphene (BP-PG) nanocomposites (PLL/BP-PG) onto the surface of glassy carbon electrodes (GCE), which were further modified with gold nanoparticles (AuNPs) to combine with a thiolated aptamer (Apt) capable of specifically recognizing Hg2+. BP-PG was synthesized using the solvothermal method and covalently bonded to form BP-PG nanosheets, resulting in significant enhanced electrochemical properties of the PLL/BP-PG composite. Furthermore, the PLL/BP-PG composite was improved environmental stability of BP and provided a considerable quantity of -NH2 for bonding to AuNPs firmly by assembling. The physical properties and electrochemical behavior of the substrate materials were investigated using various characterization techniques, and analytical parameters were optimized. It is shown that, the Apt/AuNPs/PLL/BP-PG/GCE had a linear response (R2 = 0.999) with good selectivity and high sensitivity over the Hg2+ range of 1–10,000 nmol/L. The proposed sensor has a detection limit of 0.045 nmol/L and can be employed for detecting of Hg2+. It also obtained satisfying results in river water, soil and vegetable samples.