Wulff-type boronic acids suspended hierarchical porous polymeric monolith for the specific capture of cis-diol-containing flavone under neutral condition

Abstract

An apparent disadvantage of boronate affinity is that it has to be performed in alkaline media and can lead to the oxidation of cis-diols in compounds. A new strategy named as post functionalization with B-N coordination complex was present to prepare boronic acid suspended macroporous polymeric monolith for the selective capture of cis-diol-containing luteolin (LTL) under neutral condition. In this work, a water-in-oil (W/O) Pickering (high internal phase emulsions) HIPE template stabilized by boronic acid suspended mesoporous silica nanoparticles (BA-MSNs) was applied to prepare macroporous poly(glycidyl methacrylate) monolith (PGM-Pickering-0.10), and then B-N coordination complex resulted from the reaction of 3-aminophenylboronic acid (APBA) and 1,6-hexamethylenediamine was integrated to the PGM-Pickering-0.10. As-prepared hierarchical porous PGM-Pickering-0.10-BN with “Wulff-type boronic acids” possessed special mesopore-in-macropore structure. In static adsorption, pH-dependent adsorption experiments demonstrated that PGM-Pickering-0.10-BN was able to capture LTL with expected high adsorption amount (158.5µmolg−1 at 298K) and fast binding kinetics (equilibrium in 2.0h) under neutral condition, while macroporous polymers without post functionalization or functionalized only with APBA display poor adsorption performance at pH=7.0. In addition, BA-MSNs as the stabilizers enhanced the mechanical property and specific adsorption ability of PGM-Pickering-0.10-BN simultaneously, and the integrated B-N coordination complex did play vital roles in the specific adsorption of LTL. By optimizing dynamic adsorption factors with response surface methodology (RSM), the maximum adsorption amount of 177.8µmolg−1 was also achieved under neutral condition.