Production of Bio-Mimetic Nanoparticles for the Detection of Ascorbic Acid

Abstract

An economical, sensitive and new approach based on colorimetric and UV- visible of ascorbic acid (AA) is developed. The mechanism of this method is the oxidation of 3,3',5,5'- Tetramethylbenzidine TMB with the material of the synthesis to create the oxidized TMB of a blue shade (ox-TMB). The ox-TMB is then reduced by the ascorbic acid leading to a decrease in the color intensity which can be both visually and quantitatively determined with the help of a UV Vis scanner. The main experimental parameters of the concentration of materials, TMB concentration, pH and concentration of the analyte were adjusted to improve sensing result. The most favorable conditions were found to be material concentration of 5µM, 0.5µM TMB and an acidic medium with a pH of 3-4. The response had a high reliance on pH indicating a change in color in an acidic conditions and no response at neutral and alkaline conditions (pH 7-11). The UV-vis absorbance at 652 nm under such optimized parameters reduced proportional to the change in AA concentration. High sensitivity was observed in the linear response in the concentration range of 2-5 nM where it had the lowest limit of 1.18 nM detection limit (LOD) and the highest limit of 3.59 nM was the quantification limit (LOQ). The technique proved to be very selective to the AA with minimum signal interference with the normal substances such as dopamine, glucose, cholesterol, urea, uric acid, amino acids, and the metal ions. The feasibility of the sensor was shown by using samples of diluted lemon and orange juice that were able to recover diluted samples of 97.98%-101.11%. To conclude, this has created sensing platform is easy, fast, accurate, and cheap, and therefore can be utilized in ascorbic acid detection in food samples and the future portable sensing platform is achievable.