Sensitive Oxidation of Sorbitol-Mediated Fe2+ by H2O2: A Reliable TD-NMR Method for Clinical Blood Glucose Detection

The clinical challenge of high-accuracy blood glucose detection schemes is to overcome the detection error caused by the background interferences in different individuals. H2O2 as the specific product of glucose oxidation can be involved in the Fe2+/Fe3+ conversion and detected by the time-domain nuclear magnetic resonance (TD-NMR) method sensitively. But, in clinical applications, the oxidation of Fe2+ is susceptible to the complex sample substrates. In this work, we sorted out two kinds of possible interference mechanisms of Fe2+ oxidation in the NMR blood glucose detection method and proposed a feasible scheme that uses sorbitol to weaken the adverse effects of interference. We found that sorbitol-mediated Fe2+ can greatly enhance the sensitivity of the T2 value to H2O2. The chain reaction caused by sorbitol can significantly amplify the efficiency of Fe2+ oxidation at the same concentration of H2O2. Thereby, we can achieve the higher dilution multiple of serum samples to reduce the amount of interfering substances involved in the Fe2+/Fe3+ conversion. We justified the accuracy and availability of our method by successfully detecting and confirming the correlation between the T2 decrease and glucose concentration of the serum samples collected from 16 subjects. The sorbitol-Fe2+ glucose detection method with high sensitivity can be further combined with miniature NMR analyzers to satisfy the calibration requirements of glucose monitoring in diabetic patients instead of frequent medical visits.