Facile biosurfactant assisted biocompatible α-Fe2O3 nanorods and nanospheres synthesis, magneto physicochemical characteristics and their enhanced biomolecules sensing ability

Recently, non-spherical magnetic iron oxide nanoparticles have attracted much attention, because of their shape-dependant potential applications in biosensors and magnetic storage devices. In this work, a simple, novel, environmentally friendly, energy inexpensive, toxic free synthetic approach was utilized to synthesize alpha-Fe2O3 nanorods with an aspect ratio of 10 and homogeneously dispersed 30 nm alpha-Fe2O3 nanospheres (from TEM and FE-SEM images) using non-toxic Centellasaponin biosurfactant/capping agent tapping the big polar and non-polar head saponin induced anisotropic growth. The alpha-Fe2O3 nanorods and nanospheres synthesized by the template-free, low cost, simple, energy intensive route were confirmed by FTIR, XRD and the X-ray photoelectron spectroscopy by the appearance of electron binding energy at 710.74 eV and 724.2 eV corresponding to 2P(3/2) and 2P(1/2) core levels of alpha-Fe2O3 nanoparticles. Nano alpha-Fe2O3 spheres and rods synthesized at different temperatures and various concentrations exhibit superparamagnetic characteristics consisting of a single magnetic domain of nanoparticles with no discernible coercivity and remanance with not ending magnetic saturation hysteresis and will find potential applications in magnetic recording and targeted drug delivery. Nano alpha-Fe2O3 magnetic particles displayed excellent electrochemical sensing activities towards dopamine and uric acid with 320 mV and 260 mV wider separation on alpha-Fe2O3 nanorods and alpha-Fe2O3 nanospheres, respectively at 90-170 mV reduced potential with 100% increased current response. With good selectivity and sensitivity, the alpha-Fe2O3 nanostructures could be applied in the determination of dopamine in injectable medicine and uric acid in urine samples.