Molecularly imprinted polymers in the analysis of chlorogenic acid: A review

Chlorogenic acid, a phenolic compound, is prevalent across various plant species and has been known for its pharmacological advantages. Health care experts have identified chlorogenic acid as a potential biomarker for treatment of a wide range of illnesses. Therefore, achieving efficient extraction and analysis of chlorogenic acid from plants and their products has become essential. Molecularly imprinted polymers (MIPs) are highly effective adsorbent for the extraction of chlorogenic acid from complex matrices. Currently, there is a lack of comprehensive review article that consolidate the methods utilized for the purification of chlorogenic acid through molecular imprinting. In this context, we have surveyed the common approaches employed in preparing MIPs specifically designed for the analysis of chlorogenic acid, including both conventional and newly developed. This review discusses the advantages, limitations of polymerization techniques and proposed strategies to produce more efficient MIPs for chlorogenic acid enrichment in complex samples. Additionaly, we present advanced imprinting methods for designing MIPs, which improve the adsorption capacity, sensitivity and selectivity towards chlorogenic acid.

Boronate Avidity Assisted by Dendrimer-like Polyhedral Oligomeric Silsesquioxanes for a Microfluidic Platform for Selective Enrichment of Ubiquitination and Glycosylation

A new strategy of improving boronate avidity with good accessibility of sites was suggested by utilizing a dendrimer-like structure of boron materials based on octavinyl-polyhedral oligomeric silsesquioxanes (Ov-POSS). 3-(Acrylamido)phenylboronic acid (AAPBA) was used as a functional monomer and ethylene glycol dimethacrylate (EDMA) and Ov-POSS as cross-linkers. The resulting Ov-POSS cross-linked boron monolith exhibited 27 times stronger affinity for glycoproteins than the Ov-POSS-free monolith. Importantly, the bonding strength of the poly(AAPBA-co-Ov-POSS-co-EDMA) monolith to the glycoproteins with multiple sugars, horseradish peroxidase (HRP) was 4 orders of magnitude higher than that of the single cis-diol-containing compound. The resulting monolith was used as a part of a microfluidic platform for online processing of the protein extracts from mouse liver, which integrated five functions, including protein grading, denaturation, enzymatic hydrolysis, and enrichment of glycopeptides and ubiquitin-modified peptides. The sample processing time can be reduced by nearly half compared to the offline method. Moreover, 86.7% of glycopeptides and 75% of glycoproteins were newly identified after treatment. All of the results indicated that the synergistic strategy of Ov-POSS cross-linking can significantly improve trace glycosylation's binding capacity and enrichment performance. The microfluidic platform developed may provide a promising technical tool for automated, high-efficiency, high-throughput analysis for post-translational modification proteomics.

Advances in Production of Hydroxycinnamoyl-Quinic Acids: From Natural Sources to Biotechnology

Hydroxycinnamoyl-quinic acids (HCQAs) are polyphenol esters formed of hydroxycinnamic acids and (-)-quinic acid. They are naturally synthesized by plants and some micro-organisms. The ester of caffeic acid and quinic acid, the chlorogenic acid, is an intermediate of lignin biosynthesis. HCQAs are biologically active dietary compounds exhibiting several important therapeutic properties, including antioxidant, antimicrobial, anti-inflammatory, neuroprotective, and other activities. They can also be used in the synthesis of nanoparticles or drugs. However, extraction of these compounds from biomass is a complex process and their synthesis requires costly precursors, limiting the industrial production and availability of a wider variety of HCQAs. The recently emerged production through the bioconversion is still in an early stage of development. In this paper, we discuss existing and potential future strategies for production of HCQAs.

Ovalbumin coated Fe3O4 nanoparticles as a nanocarrier for chlorogenic acid to promote the anticancer efficacy on MDA-MB-231 cells

Chlorogenic acid (5-CQA), a phenolic acid abundant in plants and herbs, has various beneficial effects on human health. However, 5-CQA undergoes biotransformation during gastrointestinal digestion, which affects its biological accessibility....

6-Aminopyridine-3-boronic acid functionalized magnetic nanoparticles for highly efficient enrichment of cis-diol-containing biomolecules

Boronate affinity materials, as efficient sorbents for extraction, separation and enrichment of cis-diol-containing biomolecules, have attracted more and more attention in recent years. However, conventional boronate affinity materials require a basic binding pH (usually 8.5), which gives rise to not only inconvenience in operation but also the risk of degradation of labile compounds, and suffer from low binding affinity, which make the extraction of cis-diol-containing compounds of low concentration difficult or impossible. In order to reduce the binding pH to neutral or acidic conditions and improve binding affinity, we present a type of material, 6-aminopyridine-3-boronic acid functionalized magnetic nanoparticles, with affinity towards cis-diol-containing biomolecules. 6-Aminopyridine-3-boronic acid, exhibiting low binding pH, high affinity and excellent water solubility toward cis-diol-containing compounds, was first employed as an affinity ligand. The result indicated that the boronate affinity MNPs exhibited low binding pH (5.0) and high binding affinity toward cis-diol-containing biomolecules. Such a property enabled the selective extraction of cis-diol-containing biomolecules with low concentration under neutral or acidic conditions. This feature greatly favored the selective enrichment of cis-diol-containing biomolecules with low concentration from real samples. The feasibility for practical applications was demonstrated with the selective enrichment of cis-diol-containing biomolecules with low concentration in a human urine sample.

Fabrication of acid-resistant imprinted layer on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle

The common elution process of molecularly imprinted polymers (MIPs) is carried out in an acidic medium, which greatly affects the stability and reusability of synthetic MIPs, especially for magnetic MIPs. In this study, we fabricated an acid-resistant imprinted layer formed by phase-transitioned lysozyme on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle, which often coexists with structural analogs. The newly designed acid-resistant imprinted layer can not only protect the internal magnetic core from denudation and dissolution, but also maintain the integrity of the imprinted layer during the elution process. The resultant magnetic MIPs exhibited good stability with no change on morphology after the repeatedly eluting process, and satisfactory reusability that can be used at least ten adsorption-desorption cycles with almost no decrease for adsorption capacity. In addition, the resultant materials possess satisfactory magnetism, uniform morphology with typical core-shell structure, stable crystallization, and good adsorption performance showing on high adsorption amount (10.82 mg g^-1), fast kinetic equilibrium time (as short as 30 min), and satisfactory selectivity (IF = 2.85, SC > 1.5). At last, the obtained magnetic MIPs as adsorbents coupled with HPLC were successfully used to selective extract CGA in Honeysuckle samples with the high recoveries in the range of 92.0-104.4%, and the contents of CGA in Honeysuckle samples from the different origin are calculated in the range of 0.98%-1.24%.

Microwave-assisted preparation of a molecularly imprinted monolith combining an imidazolium ionic liquid and POSS for enhanced extraction of baicalin-like compounds in Scutellaria baicalensis by means of in-capillary SPME followed by on-line LC and off-line LC-MS/MS

An imidazolium-type ionic liquid and polyhedral oligomeric silsesquioxane were combined to produce an imprinted monolith in capillary endowed with wide selectivity to enrich baicalin and its analogues for analysis by multidimensional LC systems.