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Hydrophilic interaction liquid chromatography (HILIC) has inherent advantages in the separation of hydrophilic or strongly polar substances (e.g., saccharides, glycopeptides, metabolites, etc.) due to strong hydrophilic interactions, which represents an attractive complementary approach to the mainstreamed reversed phase LC. Significant improvement in sensitivity, analyte coverage, throughput, analysis speed, and resolution of HILIC largely promote the development of bio-separation and bio-analytical chemistry. Based on the theoretical guidance, a lot of functional hydrophilic materials have emerged, what follows is that people are more concerned about their innovations and breakthroughs. Meanwhile, the combination of HILIC with various separation and characterization techniques (such as HILIC MS, multidimensional LC) present high separation efficiency towards complex samples in the fields of proteomics, metabolomics, food, and medicine industry. In this review the latest progress in HILIC in the past five years are summarized in order to provide a reliable and perfect guidance for future research in bio-separation. • HILIC has been playing an irreplaceable role in many separation fields and shown unlimited development potential. • Recent developments in the advanced applications of HILIC are discussed emphatically. • A lot of modified functional hydrophilic materials have emerged and their future possibilities are discussed. • This review will provide a reliable and perfect guidance for future research in bio-separation. [ABSTRACT FROM AUTHOR]

Natural products are rather complex samples containing a large number of compounds ranging from polar to nonpolar, small molecules to macromolecules, as well as numerous homologs/analogs with quite similar structures, which create great opportunities and treasures for discovery of bioactive drugs. For the purpose of better understanding the complex natural products and controlling their qualities, powerful analytical techniques for adequately separating chemical constituents and tracking potentially bioactive components are quite essential. Here, a design concept of bidirectional β-cyclodextrin (β-CD)–modified chromatographic stationary phase toward separation of bufadienolides extracted from toad is proposed. Bufadienolides could be divided into two classes: toad venom ligand (AAUBs) and toad toxin (AACBs) with remarkable differences in structures and polarity. The hydrophobic cavity of β-CD can encapsulate the steroid part of AACBs while the hydroxyls exposed on the β-CD surface have strong hydrophilic interactions with the arginine part of AACBs. Isothermal titration calorimetry and hydrogen nuclear magnetic resonance titration experiment further validate the rationality of this design. Furthermore, the β-CD-based stationary phase can be used as a hydrophilic material to construct a HILIC × RPLC 2D separation mode for the separation of AACBs, also works as a reverse phase material to construct a RPLC × RPLC 2D separation mode for the separation of AAUBs with good orthogonality. This study will open an avenue and provide a novel insight for high-efficiency two-dimensional separation of natural products. [ABSTRACT FROM AUTHOR]

Separation, purification, and identification of glycoproteins are essential for understanding their vital roles in biological and pathological processes. However, glycoproteins are difficult to be captured due to their low abundance, strong interference from non-glycosylated proteins. Here, we report a promising dipeptide-based saccharide recognition platform to selectively enrich two typical glycoproteins, named immunoglobin G (IgG) and horseradish peroxidase (HRP). Different from the conventional glycoprotein enrichment method based on boronic acid affinity or hydrophilic interaction with glycans, the present method was established based on affinity between Pro-Glu (PE) dipeptide and mannose, which is a key unit in the pentasaccharide core of the IgG and HRP glycans. The prepared PE homopolymer surface was proved to selectively bind IgG and HRP superior to that of bovine serum albumin (BSA). Benefiting from this feature, selective enrichment of IgG and HRP was achieved from a protein mixture containing 200-fold BSA interference by using polyPE@SiO 2 under a dispersive solid-phase extraction (dSPE) mode. High adsorption capacity, controllable and selective adsorption behaviors, as well as satisfactory recovery demonstrated the high potential of the dipeptide-based polymeric material in IgG and HRP enrichment. This study might provide a new insight to solve the challenging problem of glycoprotein separation. [Display omitted] • A dipeptide-based saccharide recognition platform was developed in selectively enriching two glycoproteins. • A key pentasaccharide core was established based on the affinity between dipeptide and mannose. • This method had high adsorption capacity, controllable and selective adsorption behaviors, and satisfactory recovery [ABSTRACT FROM AUTHOR]