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

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 Zn into DM-MIPs. First, Zn-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 boronic acid monomer 4-(2-acrylamidoethylcarbamoyl)-3-fluorophenylboronic acid (AMC-FPBA) via the second SI-ATRP. Taking advantage of low apparent pK 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), 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.

Dual-Responsive Nanotubes Assembled by Amphiphilic Dendrimers: Controlled Release and Crosslinking

“…Halloysite nanotubes (HNTs) were purchased from the Guangzhou Runwo Materials Technology Co., Ltd. (Guangzhou, China), followed by fine grinding and purification according to previous reports [20][21][22][23]. Amphiphilic dendrimers G n C 12 (n = 1, 2, 3) were synthesized as shown in Scheme S1 and the detailed characterization results are exhibited in Figures S1-S3.…”

Boronate-modified polyethyleneimine dendrimer as a solid-phase extraction adsorbent for the analysis of luteolin via HPLC

“…In recent years, some common methods for separation and purification of LTL have been reported, such as thin-layer chromatography, resin adsorption, column chromatography, acid precipitation, and so on. 8 These methods need to spend a lot of time and money, and the recovery efficiency and purity are not very high, often not selected by the majority of people. 9 At present, covalent affinity is of interest among various research groups.…”

Thiol–Yne Click Synthesis of Polyamide–Amine Dendritic Magnetic Halloysite Nanotubes for the Efficient Removal of Pb(II)

“…Their potential to be used as an interface for further applications can be enhanced by their surface modification. Herein, we use halloysite nanotubes (HNTs) as PAMAM-functionalized supports. − HNT is an aluminosilicate dioctahedral 1:1 clay mineral structure with the molecular formula Al 2 Si 2 O 5 (OH) 4 · n H 2 O in the form of hydration and dehydration . As a clay mineral, it has one-dimensional tubular structure, large internal and external surface area, Al–OH groups on the inner surface of the nanotubes, and Si–O–Si groups on the outer surface, as well as provides wealth of active adsorption sites and the sites for the attachment of functional groups in aqueous solution of various contaminants .…”