Epitope-Imprinted Polymer Nanoparticles Enable Selective Recognition of Filamentous Vimentin for Tumor Imaging In Vivo.

Vimentin is a cytoskeletal protein upregulated during epithelial-mesenchymal transition that can also be aberrantly displayed on the surface of multiple tumor cell types, making it a promising target for tumor imaging. Here, we develop epitope-imprinted polymer nanoparticles (nanoMIPs) for vimentin recognition through a two-step strategy comprising screening a library of non-imprinted nanoparticles to identify a lead formulation, followed by peptide-directed molecular imprinting. The resulting nanoMIPs exhibited enhanced apparent affinity for vimentin, with picomolar-range KD values, although these values represent model-dependent ensemble apparent affinities that may include contributions from multiple nanoparticle-ligand contacts and local rebinding rather than intrinsic monovalent affinities. The nanoMIPs preferentially bound cancer cells presenting cell-surface vimentin in vitro. The enhanced target binding and reduced off-target binding were consistent with an imprinting-associated improvement in molecular discrimination, although nonspecific physicochemical interactions were not completely eliminated. These findings extend epitope-guided nanoMIP design to structurally dynamic, cell surface-associated cytoskeletal targets, and support the development of synthetic receptors for tumor imaging. In vivo, the optimized nanoMIPs produced a tumor-associated fluorescence signal approximately 1.44 times that of the matched non-imprinted nanoparticles.