Molecularly imprinted nanoparticles were prepared using a simple distillation precipitation polymerization method. In this work, propranolol-imprinted nanoparticles were synthesized using different cross-linkers combined with methacrylic acid (MAA) as a functional monomer in refluxing acetonitrile. Using the new synthetic method, uniform prorpanolol-imprinted nanoparticles were obtained in less than 3 h, which is in contrast to the long reaction time (24 h) required in previous precipitation polymerization. The new synthetic method also provides a convenient means to prepare core−shell structured nanoparticles, where the core contains imprinted binding sites and the shell has more hydrophilic characteristics. Molecular recognition properties of the imprinted nanoparticles were studied through equilibrium binding experiments. For nanoparticles containing N,N′-methylenebis(acrylamide) cross-linker, the residual CC bonds remaining in the nanoparticles were utilized to immobilize a fluorescent compound, 1-pyrenemethylamine, through nondestructive Michael addition reaction. The fluorescent modification did not deteriorate the molecular recognition property of the nanoparticles, suggesting that the Michael addition reaction took place only in nonselective sites. Using a similar Michael addition reaction, we anticipate that the residual CC bonds in the acrylamide moiety can be utilized to introduce other reporter molecules into molecularly imprinted nanoparticles or to immobilize such nanoparticles on amine- or thiol-functionalized surfaces to develop different chemical sensors. The hydrophilic shell of the imprinted core−shell nanoparticles shall provide effective screening to prevent nonspecific adsorption of, e.g., proteins while allowing small target molecules to enter the imprinted sites in the more hydrophobic core, thereby potentially useful for extraction of small organic molecules from complex biological samples.

Since the molecular weights of epitopes are typically in the range of 500-3000 Da and have the properties of small molecules, monomers, and crosslinkers commonly used for small-molecule imprinting could also be used for epitope imprinting. [1d,4a] Moreover, epitopes, as alternatives to protein templates, are usually used to fabricate imprinted materials

GO-PEI-Au-L-Cys composites were synthesized via loading gold nanoparticles on a GO surface using polyethylenimine as reducing and stabilizing reagents, followed by L-cysteine immobilization through an Au-S bond. The composites were applied as a kind of novel ZIC-HILIC material to achieve highly selective enrichment of glycopeptides from biological samples.

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The boronic acid-functionalized core-shell polymer nanoparticles, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@4-vinylphenylboronic acid (poly(MBA-co-MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid-functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time-saving. With the poly(MBA-co-MAA)@VPBA nanoparticles, 18 glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI-TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta-aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5 nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA-co-MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis.

A new type of IMAC material, with ATP as the chelating ligand, was synthesized and applied to capture phosphopeptides. For the first time, the approach for phosphopeptide enrichment could provide selectivity under 5000-fold dilution by nonphosphopeptides, and sensitivity of on-target enrichment at 3 amol.Reversible protein phosphorylation, a ubiquitous post-translational modification, plays pivotal roles in various biological procedures such as signal transduction, cell cycle, gene expression and enzymatic regulation.1,2 However, phosphoproteome analysis faces substantial challenges, due to its low dynamic stoichiometry and suppression from nonphosphopeptides in mass spectrometry (MS) analysis. The selective enrichment of phosphopeptides before MS analysis is thus an essential step for in-depth phosphoproteome study. [3][4][5][6] To date, immobilized metal affinity chromatography (IMAC) has been the most frequently used technique to isolate phosphopeptides.3 Binding of non-phosphopeptides that contain acidic amino acid residues represents the major limitation of this method. Recently, phosphonate polymers were used to coordinatively bind Ti 4+ or Zr 4+ , 7-10 and for the first time the resulting IMAC showed high selectivity toward phosphopeptides even under 500-fold dilution by nonphosphopeptides. To discover trace phosphorylated proteins or peptides with great biological significance, it is urgent to develop a more selective and sensitive enrichment approach to go through in-depth phosphoproteome analysis.The improvement in the selectivity of IMAC by phosphonate polymers demonstrated that the chelating ligand played a critical role in the performance of IMAC. However, the presently applied phosphonate ligands usually contain only one phosphate group, which need to cooperate with neighboring ligands to achieve the immobilization of metal ions. 11 The performance of such materials is seriously restrained by the density of ligands on the matrices. Besides, the hydrophobic alkyl residues in these ligands might lead to the nonspecific adsorption of non-phosphopeptides via hydrophobic interaction, and the loss of highly hydrophilic phosphopeptides. In addition, such phosphonate ligands are easy to be hydrolyzed in air, making the preparation conditions for such materials harsh and hard to follow. Therefore, a novel chelating ligand for IMAC may be in great demand, to probe trace phosphorylated biomolecules. Adenosine tri-phosphate (ATP) is an important signaling biomolecule, which regulates various biological functions in cells.12-15 The ATP molecule, composed of three phosphate groups, could offer superiorly strong and active metal phosphonate sites to bind phosphopeptides. Besides, its hydrophilic purine base and pentose sugar groups might contribute great hydrophilicity to decrease the non-specific adsorption of non-phosphopeptides. The unique structure and good biocompatibility of ATP make it a ligand with great potential to prepare IMAC materials.In this work, we exploited ATP as a kind of novel IMAC ligand to ...

The specific recognition of biomolecules by artificial antibodies has inspired fascination among chemists and biologists. Herein, we propose a new method to prepare epitope-oriented surface-imprinted nanoparticles with high template utilization efficiency. Using a His-tag as the anchor to facilitate the epitope immobilization/removal and the self-polymerization of dopamine to control the imprinted shell thickness, the prepared epitope-imprinted nanoparticles show specific recognition of the target protein. Moreover, with improved hydrophilicity of the His-tag-anchored epitope, this method opens up a universal route for imprinting epitopes with various polarities.