Sustainable synthesis of hierarchically grown chloramphenicol-imprinted poly(caffeic acid) nanostructured films

Hierarchically nanostructured chloramphenicol (CLP) imprinted thin polymer films have been developed using a renewable monomer, the antioxidant caffeic acid (CA), using sacrificial nanostructures to induce porosity into the films. The poly(caffeic acid) (PCA) films were synthesized on Au/quartz resonators via greener polymerization conditions (clean energy electropolymerization in aqueous buffer or a non-ionic deep eutectic solvent). The sacrificial nanostructures explored included zein-based protein nanobeads, anodized alumina membrane, and Tween 20-derived polysorbate micelles, where dissolution of the sacrificial nanostructure templates from the PCA films afforded uniform long-range hyperporous networks, nanowires and nanoparticles, respectively, as revealed by SEM studies. Selective extraction of the CLP template from PCA films, was monitored by XPS, and afforded CLP selective cavities. The CLP-imprinted PCAzein films demonstrated eight- to 25-fold higher sensitivity than the other nanostructures in a QCM-sensor format, the limit of detection (LOD) under optimized FIA conditions was 50 mM. Significant sensitivities for CLP in milk were observed (1.5 μg/ml to 3 mg/ml), covering the clinically relevant concentration range. The PCAzein thin films selectively differentiate CLP from structurally related antibiotics and are robust. Their production from renewable feedstocks of biological origin highlights the potential of this class of nanostructured materials for applications utilizing thin films.