Starch-Assisted Molecularly Imprinted ZIF-90 for Enhanced Extraction of Baicalin Followed by Chromatographic...

This work addresses the challenge of imparting molecular selectivity to metal-organic frameworks (MOFs) by developing a molecularly imprinted polymer based on ZIF-90 (MI-ZIF). Starch was used as a green and multifunctional auxiliary polymer during a room-temperature preparation of MI-ZIF with baicalin as the template. This strategy leverages the hydroxyl groups of starch to orchestrate the formation of specific recognition cavities within the ZIF-90 framework. The well prepared MI-ZIF exhibited high adsorption capacity and good specificity, with an imprinting factor (IF) of 4.1. The MI-ZIF was used to enrich baicalin from complex matrices such as plant extracts and serum samples. It achieved a high adsorption rate of 93.2% for baicalin from a Scutellaria baicalensis Georgi (SBG) root extract, increasing the baicalin purity from 19.7% to 71.3%. As a solid-phase extraction sorbent for the analysis of serum samples, this method showed high sensitivity with a detection limit of 0.9 ng mL^-1 and recoveries in the range of 78.2%-97.2%. The results indicate that the MI-ZIF can significantly improve the enrichment efficiency and detection sensitivity of baicalin, providing an efficient and reliable technical means to solve the problems of enrichment, separation, and trace detection of flavonoid compounds in complex samples.