A choline chloride-acrylic acid deep eutectic solvent polymer based on Fe3O4 particles and MoS2 sheets (poly(ChCl-AA DES)@Fe3O4@MoS2) with specific recognition and good antibacterial properties for β-lactoglobulin in milk

With the development of deep eutectic solvents (DESs), more DES-based functional materials have been explored and applied in various areas. In this work, a novel choline chloride-acrylic acid (ChCl-AA) DES polymer, on a 2D magnetic base, was prepared for the recognition of β-lactoglobulin (β-LG) biomacromolecules in milk and for the inhibition of common bacteria such as Escherichia coli (E. coli), Pseudomonas fluorescens (P. fluorescens), Staphylococcus aureus (S. aureus), and Bacillus subtilis (B. subtilis). The ChCl-AA DESs were polymerized on the surface of 2D MoS2 sheets doped with nano Fe3O4 particles, and the resulting polymer was abbreviated poly(ChCl-AA DES)@Fe3O4@MoS2. The free energy (ΔG=−92) of ChCl-AA DES was calculated using the Gaussian software, the composition and structure of poly(ChCl-AA DES)@Fe3O4@MoS2 were characterized by field emission scanning electron microscopy, transmission electron microscopy, etc., the qualitative and quantitative analyses of β-LG were done by fluorescence spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis and high performance liquid chromatography, and the bioactivity of bacteria was analyzed by flat colony counting. Based on the present analysis, poly(ChCl-AA DES)@Fe3O4@MoS2 specifically recognized β-LG in a good fitting Langmuir isotherm (R2 = 0.9909) and second-order kinetic model (R2 = 0.9989) by affinity, and evidently inhibited three bacteria, namely, E. coil (65%), S. aureus (50%), and B. subtilis (54%), effectively reducing the relative colony number. As the poly(ChCl-AA DES)@Fe3O4@MoS2 material did not only exhibit specific recognition of biomacromolecules, but also had an antimicrobial effect against common bacteria, it could be an ideal separation media or carrier for biomacromolecules in real samples.