Mechanism Analysis of Selective Adsorption and Specific Recognition by Molecularly Imprinted Polymers of Ginsenoside Re

Abstract

In this article, the molecularly imprinted polymers (MIPs) of ginsenoside Re (Re) were synthesized by suspension polymerization with Re as the template molecule, methacrylic acid (MAA) as the functional monomers, and ethyl glycol dimethacrylate (EGDMA) as the crosslinker. The MIPs were characterized by Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and surface porosity detector, and the selective adsorption and specific recognition of MIPs were analyzed using the theory of kinetics and thermodynamics. The experimental results showed that compared with non-imprinted polymers (NIPs), MIPs had a larger specific surface area and special pore structure and that different from the Langmuir model of NIPs, the static adsorption isotherm of MIPs for Re was in good agreement with the Freundlich model based on the two adsorption properties of MIPs. The curves of the adsorption dynamics and the lines of kinetic correlation indicate that there was a fast and selective adsorption equilibrium for Re because of the affinity of MIPs to the template rather than its analogue of ginsenoside Rg1 (Rg1). The study of thermodynamics indicate that the adsorption was controlled by enthalpy and that MIPs had higher enthalpy and entropy than NIPs, which contributed to the specific recognition of MIPs.

Noncovalently D-arabinitol Molecularly Imprinted Polymers (MIPs) to Identify Different Sugar Alcohols

“…in which Qm (μmol/ g) and Qe (μmol/ g ) represents the adsorbent maximum and equilibrium capacity, respectively; b (mL/ μmol) represents the adsorption equilibrium constant; and Ce (μmol/ mL) represents the D-arabinitol equilibrium concentration 18 The selectivity of the MIPs D-arabinitol MIPs and NIPs selectivity were determined using a batch system. MIPs and NIPs D-arabinitol were each added to 10 mL of an enantiomer solution (L-arabinitol, xylitol, adonitol) and glucose in water, respectively, 0.053 μmol/ mL.…”

“…In this study, selectivity was determined using a batch rebinding method 18,19 , namely, by adding D-arabinitol, L-arabinitol, xylitol, adonitol, and glucose to MIPs and NIPs in the same number of moles and incubating the compounds for 7 hours. The results regarding the selectivity of each compound are presented in the following Tab.…”

Comparison of Four Adsorption Isotherm Models for Characterizing Molecular Recognition of Individual Phenolic Compounds in Porous Tailor-Made Molecularly Imprinted Polymer Films

“…43−47 The LI model has been used to characterize MIP adsorption based on these assumptions. 12,13 The Langmuir equation (eq 1) illustrates the assumed relationship between the amount of bound (B) analyte and the free analyte in the system (C e ) at equilibrium:…”

“…Adsorption isotherm models have already been used to characterize interactions between analytes and MIP surfaces to enhance understanding of the adsorption chemistry and to provide numerical descriptors of MIP binding properties for comparison of performance. ,− Models that are applied to MIPs include Langmuir (LI), Freundlich (FI), and Langmuir–Freundlich (L-FI) isotherms . Although the Brunauer, Emmett, and Teller (BET) isotherm model has not been previously used to characterize MIPs, its ability to model multilayer formation warrants investigation of its suitability .…”

“…In 1916, Irving Langmuir introduced a new adsorption isotherm model to describe the adsorption behavior of gaseous molecules onto a solid surface at a constant temperature; the eponymous Langmuir isotherm is the most widely used model for adsorption studies. , LI assumes that all surface binding sites are the same, adsorption cannot occur beyond monolayer coverage, and each binding site can be occupied by only one molecule. − The LI model has been used to characterize MIP adsorption based on these assumptions. , The Langmuir equation (eq ) illustrates the assumed relationship between the amount of bound ( B ) analyte and the free analyte in the system ( C e ) at equilibrium: where N is the binding site density and K is the adsorption constant (a measure of the adsorbate affinity). This equation can be rearranged into a linear form (eq ) to calculate N and K by linear regression analysis: …”