Terminally Phosphorylated Triblock Polyethers Acting Both as Templates and Pore-Forming Agents for Surface Molecular Imprinting of Monoliths Targeting Phosphopeptides

Abstract

The novel process reported here described the manufacture of monolithic molecularly imprinted polymers (MIPs) using a terminally functionalized block copolymer as the imprinting template and pore-forming agent. The MIPs were prepared through a step-growth polymerization process using a melamine–formaldehyde precondensate in a biphasic solvent system. Despite having a relatively low imprinting factor, the use of MIP monolith in liquid chromatography demonstrated the ability to selectively target desired analytes. An MIP capillary column was able to separate monophosphorylated peptides from a tryptic digest of bovine serum albumin. Multivariate data analysis and modeling of the phosphorylated and nonphosphorylated peptide retention times revealed that the number of phosphorylations was the strongest retention contributor for peptide retention on the monolithic MIP capillary column.

Elucidation of the Binding Orientation in α2,3- and α2,6-Linked Neu5Ac-Gal Epitopes toward a Hydrophilic Molecularly Imprinted Monolith

“…90 The domain sizes varied inversely with the polymerization temperatures: 5.0 ± 0.39, 4.1 ± 0.54, and 2.4 ± 0.33 μm for 4, 40, and 80 °C, respectively (Figure 1b−d). However, only the sample polymerized at 80 °C formed a space-filling monolith as in our previous work, 66 whereas the other nonfreezing conditions (4 and 40 °C) led to monolithic materials that did no fill the glass vial molds entirely but underwent syneresis with ≈20 vol % expelled liquid. Despite the expected imprinting enhancement at low temperatures, it must also be noted that the rates and yields of the polymerizations and also the structures were affected by temperature in these three nonfrozen polymerization attempts.…”

“…Cross-linked melamine, utilized as a hydrophilic scaffold for MIPs, − was prepared by step-growth polymerization of melamine and paraformaldehyde in a tertiary porogen mixture adapted from our previous communication, with some modification as described in the experimental section. Polycondensation between melamine and formaldehyde occurs in the presence of H + or OH – as catalyst and is promoted by temperature. , However, increasing temperature weakens the interactions between the template and the growing polymer due to the temperature-dependent strengths of hydrogen bonds and permanent dipole-permanent dipole interactions (Keesom forces), which are essential for molecular imprinting of polar templates.…”

“…Cross-linked melamine, utilized as a hydrophilic scaffold for MIPs, 66−68 was prepared by step-growth polymerization of melamine and paraformaldehyde in a tertiary porogen mixture adapted from our previous communication, 66 with some modification as described in the experimental section. Polycondensation between melamine and formaldehyde occurs in the presence of H + or OH − as catalyst and is promoted by temperature.…”

“…Design and Synthesis of MIPs. Our recent report on a partly aqueous biphasic step-growth polymerization 66 has shown that melamine-based monoliths have preferred binding toward hydrophilic compounds with negative charge, thanks to electrostatic interaction, hydrogen bonding, and low propensity for π−π interactions. 109 We here adopted the melaminebased approach for the preparation of monolithic molecularly imprinted polymers for the Neu5Ac moiety and its glycosidic linkage conformations Neu5Ac(α2−3)Gal and Neu5Ac(α2− 6)Gal, using lactose-linked compounds 3′-and 6′-sialyllactose (3SL and 6SL) as model molecules.…”

“…46 The monoliths, prepared from melamine and paraformaldehyde (Figure 2), contain a triazine ring cross-linked by methylene and ether bridges. 66 The only "stable" (nonexchangeable) protons of the polymerized monoliths are those of the methylene bridges between amine nitrogens of the melamine molecules, or between a melamine amine and an oxygen atom originating from paraformaldehyde. The solid-state proton NMR spectra of the cross-linked melamine monoliths therefore showed a single broad peak centered around 3.40 ppm (Figure S10).…”