Shock waves exposed α-Fe2O3 nanoparticles for electrochemical sensing of riboflavin, uric acid and folic acid

Abstract

Multi-analyte detection has become an increasingly important need for on-line and in-situ monitoring in food process, biomedical and environmental monitoring industries due to its advantages like minimum sample and time requirement for analysis, improved functionality, and portability of the devices. Here, we report a novel electrochemical sensor based on shock wave treated Iron (ΙΙΙ) oxide (α-Fe2O3) nanoparticles for simultaneous detection of Riboflavin (RF), Uric acid (UA), and Folic acid (FA). The α-Fe2O3 NPs were synthesized by the sol–gel method and modified by exposing shock waves (50,100,150 pulses) with a time interval of 3 s. Both the pristine and modified nanoparticles were characterized by powder XRD, HRTEM, XPS, Raman, and Photoluminescence spectroscopy. Glassy carbon electrodes (GCE) have been modified with the α-Fe2O3NPs and their electrocatalytic activity towards the oxidation of RF, UA, and FA has been investigated in phosphate buffer saline (PBS) at pH 7.4. Among various electrodes, the α-Fe2O3 NPs exposed to 150 shock waves exhibited sharp oxidation peaks at −0.45 V, 0.4 V, and 0.8 V corresponding to oxidation of RF, UA, and FA respectively. The fabricated sensor responded selectively over wider dynamic ranges of 0.11 to 624 μM for RF, 0.11 to 722 μM for UA, and 0.11 to 691 μM for FA with the corresponding detection limits of 26, 18, and 25 nM respectively. For simultaneous determination, the SWV oxidation peak currents increased proportionally with the increase in the concentration over the range of 0.111 to 397 µM, with the relatively better LODs of 11, 14, and 16 nM for RF, UA, and FA. The influence of 100-fold excess of ascorbic acid, sucrose, thiamine (Vit.B1), urea, glucose, NaCl, KCl, histamine, ammonia, acetylcholine, ascorbic acid, and L-tyrosine were tested on the SWV response in the presence of riboflavin, uric acid, and folic acid. Applicability of the fabricated electrode has been tested using vitamin tablets and human urine as real samples.