Research on the Mechanism of Enhancing the Adsorption Capacity of Molecularly Imprinted Polymers Based on the Molecular Crowding Effect

Molecular crowding, as a crucial mechanism for regulating intermolecular interactions, has demonstrated significant application potential in materials science in recent years. This study proposes and systematically explores the enhancement effect and underlying mechanism of molecular crowding on the adsorption performance of paracetamol molecularly imprinted polymers (AMIP). By introducing glucose as a molecular crowding agent into the adsorption system of AMIP for paracetamol (APAP), the correlation between the physical parameters of the solution microenvironment and the adsorption capacity of AMIP was elucidated through nuclear magnetic resonance (NMR) transverse relaxation time and diffusion-ordered spectroscopy (DOSY) analyses. Experimental results reveal that the crowding effect emerges when the glucose concentration exceeds 10 g/L. At a glucose concentration of 500 g/L, the adsorption capacity of AMIP increases to 1.96 times that under nonmolecular crowding conditions. The primary mechanism originates from the compression of the solution's free volume by glucose through the excluded volume effect, significantly increasing the local effective concentration of APAP. Secondarily, glucose competitively binds a large number of water molecules, altering the polar microenvironment of water and weakening the hydrogen bonding between APAP and water, thereby facilitating the specific binding of APAP to AMIP. To validate the mechanism, adsorption studies on MIPs for four compounds with distinct polarities confirmed that molecular crowding enhances the adsorption capacities of both hydrophilic and hydrophobic compounds. This work provides a novel solution microenvironment strategy for optimizing MIP performance and expands the application potential of molecular crowding in the rational design of functional materials.