Using Yb-EDTA as Shift reagent for α-hydroxyl acid detection by CEST NMR

Motivation: A major challenge in detecting α-hydroxy acid using the chemical exchange saturation transfer (CEST) method is that the hydroxyl proton's resonance is close to the bulk water signal. Goal(s): This work aims to develop a shift reagent for detecting α-hydroxy acids using the CEST method with a commercially available agent. Approach: The CEST method was employed to detect α-hydroxy acid, and the Omega plot was utilized to determine the proton exchange rate. Results: The hydroxyl proton of α-hydroxy acid was successfully shifted to display a CEST signal using Yb-EDTA. Impact: The commercially available shift agent Yb-EDTA was used to detect α-hydroxy acid via the CEST method, with the signal shifted down to around 50 ppm. This demonstrates the potential for in vivo detection without interference from magnetization transfer (MT) effects.