*2.3. Characterization of Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs*

The analysis of the size and the morphology of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs were performed using field-emission scanning electron microscopy (SEM; Supra 55 Sapphire, Carl Zeiss, Jena, Germany). Thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTG) (STA 449 F5, NETZSCH-Gerätebau GmbH, Selb, Germany) were conducted to evaluate the thermal stabilities of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs under an N2 atmosphere at a heating rate of 10 K/min. The functional groups of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs were recorded by Fourier transform infrared spectrometer (MagnA-IR55, Thermo Fisher Scientific, Massachusetts, USA) in the range of 4000–400 cm<sup>−</sup>1. The chrysin solution was determined by UV-visible spectra (UV-2600 Shimadzu, Tokyo, Japan). The Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs were weighed by analytical balance with an accuracy of 0.1 mg (Practum124-1cn, Sartorius AG, Göttingen, Germany).

## 2.3.1. Scanning Electron Microscopy (SEM)

The surface morphology of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs was determined by SEM analysis (SEM, Supra 55 Sapphire, Carl Zeiss Germany, Jena, Germany). The samples were evenly coated on the conductive adhesive of the sample sheet and then sprayed with gold for 0.5 h. The surface morphology of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs after the samples were sprayed with gold was observed by SEM under low vacuum conditions.

#### 2.3.2. Diameters of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs

The diameters of the Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs were measured from their SEM images using image analysis software (Image J). The diameter of more than 60 samples in each sample were measured. AD represents mean diameter ± standard deviation, and N represents sample quantity.
