Preparation and Application of Molecularly Imprinted Polymers for Flavonoids: Review and Perspective

Abstract

The separation and detection of flavonoids from various natural products have attracted increasing attention in the field of natural product research and development. Depending on the high specificity of molecularly imprinted polymers (MIPs), MIPs are proposed as efficient adsorbents for the selective extraction and separation of flavonoids from complex samples. At present, a comprehensive review article to summarize the separation and purification of flavonoids using molecular imprinting, and the employment of MIP-based sensors for the detection of flavonoids is still lacking. Here, we reviewed the general preparation methods of MIPs towards flavonoids, including bulk polymerization, precipitation polymerization, surface imprinting and emulsion polymerization. Additionally, a variety of applications of MIPs towards flavonoids are summarized, such as the different forms of MIP-based solid phase extraction (SPE) for the separation of flavonoids, and the MIP-based sensors for the detection of flavonoids. Finally, we discussed the advantages and disadvantages of the current synthetic methods for preparing MIPs of flavonoids and prospected the approaches for detecting flavonoids in the future. The purpose of this review is to provide helpful suggestions for the novel preparation methods of MIPs for the extraction of flavonoids and emerging applications of MIPs for the detection of flavonoids from natural products and biological samples.

Keywords: applications; flavonoids; molecularly imprinted polymers; natural products; preparation methods.

Figure 1

Main subclasses of flavonoids according to their structural formulas.

Figure 2

Principle of MIPs preparation.

Figure 3

Illustration of main preparation steps of MIPs towards flavonoids using four preparation methods. (a) Bulk polymerization; (b) Precipitation polymerization; (c) Surface imprinting [43]; (d) Pickering emulsion polymerization [73].

Figure 4

Principles of MIP-based SPE for flavonoid extraction. (a) The MIPs towards flavonoids were packed into traditional SPE column for flavonoid extraction; (b) The MIPs towards flavonoids were pulled into sample solutions for flavonoid extraction by dispersive SPE; (c) The magnetic MIPs were pulled into sample solutions, separating targets and interferents by external magnetic field for flavonoid extraction.

Figure 5

MIP-based sensor. (a) The principle of AIE-MIP sensor; (b) The illustration of main preparation steps of an AIE-MIP membrane and fixing the AIE-MIP membrane with a magnetic frame for fluorescence detection. This figure is from Yan et al. [95].