Two Are Better than One: Halloysite Nanotubes-Supported Surface Imprinted Nanoparticles Using Synergy of Metal Chelating and Low pKa Boronic Acid Monomers for Highly Specific Luteolin Binding under Neutral Condition

Shucheng Liu; Jinxin Liu; Jianming Pan; Jialu Luo; Xiangheng Niu; Tao Zhang; Fengxian Qiu

doi:10.1021/acsami.7b11426

Two Are Better than One: Halloysite Nanotubes-Supported Surface Imprinted Nanoparticles Using Synergy of Metal Chelating and Low pK_a Boronic Acid Monomers for Highly Specific Luteolin Binding under Neutral Condition

ACS Appl Mater Interfaces. 2017 Sep 27;9(38):33191-33202. doi: 10.1021/acsami.7b11426. Epub 2017 Sep 14.

Authors

Shucheng Liu¹, Jinxin Liu¹, Jianming Pan^{1

2}, Jialu Luo¹, Xiangheng Niu¹, Tao Zhang¹, Fengxian Qiu¹

Affiliations

¹ School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, China.
² Department of Chemistry, Stanford University , Stanford, California 94305, United States.

PMID: 28885001
DOI: 10.1021/acsami.7b11426

Abstract

Surface-imprinted nanoparticles with double recognition (DM-MIPs) are fabricated onto halloysite nanotubes (HNTs) for highly specific separation of natural flavone luteolin (LTL) under neutral condition. Specifically, a two-step strategy via consecutive surface-initiated atom transfer radical polymerization (SI-ATRP) is employed to introduce inherent recognition of molecular imprinting and reversible covalent affinity of boronic acid ligands and immobilized Zn²⁺ into DM-MIPs. First, Zn²⁺-immobilized poly(vinyl imidazole) (PVLD) shell based on the HNTs via the first SI-ATRP is prepared to capture LTL by metal chelating. Then HNTs-supported surface imprinted nanoparticles are prepared using low pK_a boronic acid monomer 4-(2-acrylamidoethylcarbamoyl)-3-fluorophenylboronic acid (AMC-FPBA) via the second SI-ATRP. Taking advantage of low apparent pK_a of AMC-FPBA and large high-affinity binding site density, DM-MIPs possess a promising binding with cis-diol-containing LTL under neutral condition. In static adsorption, DM-MIPs show large LTL loading amount (83.42 mg g^-1), fast capture kinetics, remarkable selectivity, and excellent recyclability at pH = 7.0. More importantly, by reducing the pH to 4.0, the loaded TLL can be simply released. As a proof of this concept, a commercially available LTL with 85% purity can be easily enriched and further purified, and the product exhibits the similar antibacterial performance with standard substance.

Keywords: halloysite nanotubes (HNTs); low pKa boronic acid; luteolin (LTL); metal chelating; specific separation; surface imprinted nanoparticles.