Chitosan-functionalized PVDF and PES membranes integrated by epitope-imprinted polymers for targeted hepatitis A virus capture

Abstract

Hepatitis A virus (HAV) is primarily transmitted through contaminated water. This study developed bioselective polyvinylidene fluoride (PVDF) and polyethersulfone (PES) membranes through chitosan hydrophilic surface modification and immobilization of HAV-specific epitope-imprinted polymers (eIPs) to remove trace levels of HAV. The HAV epitope was imprinted using solid-phase synthesis, involving template immobilization on glass beads, polymerization of monomers, and elution of eIPs. The chosen epitope template from the HAV capsid knob enhanced binding affinity due to its high surface accessibility and hydrophilicity. The average hydrodynamic size, polydispersity index, and zeta-potential of the eIP particles were 232.6 nm, 0.29, and −44.36 mV, respectively, indicating their stability in liquid environments. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopies confirmed chitosan functionalization on PVDF/PES membranes. The fluorescence microscopy confirmed eIP immobilization on the membranes with the Rhodamine B monomer's strong fluorescence intensity. Atomic force microscopy (AFM) monitoring showed that eIP immobilization enlarged pore structures in PVDF membranes and improved chemical phase distribution on PES membrane surfaces. The bare PES and chitosan-functionalized PES/PVDF membranes after eIP immobilization had the lowest and highest root mean square roughness values, respectively. Morphological changes observed via scanning electron microscopy (SEM) revealed that chitosan functionalization smoothed the structures of PVDF and PES membranes by reducing porosity, while eIP immobilization increased surface irregularities with sharper edges and blob-like structures. Functionalized PVDF membranes improved hydrophilicity and filtration efficiency, whereas naturally hydrophilic PES membranes maintained consistent water absorption. Chitosan modification significantly enhanced permeation flux in PVDF and PES membranes by increasing hydrophilicity and improving filtration performance and capacity. Virus concentrations were measured pre- and post-filtration using a UV–visible spectrophotometer to assess the membrane performance. Absorbance at 215 nm showed a linear relationship with HAV virus concentrations from 0.006 to 13.5 IU mL−1, with a quantification limit of 0.36 IU mL−1 under optimal conditions. These new bioselective membranes removed 99.99 % of viruses from water samples, showing robust HAV elimination capabilities and practical potential for drinking water purification.