Retargeting Polyomavirus-Like Particles to Cancer Cells by Chemical Modification of Capsid Surface

Virus-like particles based on polyomaviruses (PVLPs) are promising delivery devices for various cargoes, including nucleic acids, imaging probes, and therapeutic agents. In biological environments, the major coat protein VP1 interacts with ubiquitously distributed sialic acid residues, and therefore PVLPs show a broad tropism. For selective targeting, appropriate engineering of the PVLP surface is needed. Here, we describe a chemical approach to retarget PVLPs to cancer cells displaying abnormally high levels of transferrin receptor. We created an array of transferrin molecules on the surface of PVLPs by combining a high-yielding bioconjugation approach with specific point modification of transferrin. This artificial surface protein architecture enables (i) suppression of natural VP1-specific interactions by blocking the surface conformational epitope on the VP1 protein, (ii) unusually high cellular uptake efficiency, and (iii) selective retargeting of PVLPs to osteosarcoma (U2OS) and lymphoblastoid leukemia (CCRF-CEM) cells

Supported Lipid Bilayers on Fluorescent Nanodiamonds: A Structurally Defined and Versatile Coating for Bioapplications

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Inhibitor–GCPII Interaction: Selective and Robust System for Targeting Cancer Cells with Structurally Diverse Nanoparticles

Glutamate carboxypeptidase II (GCPII) is a membrane protease overexpressed by prostate cancer cells and detected in the neovasculature of most solid tumors. Targeting GCPII with inhibitor-bearing nanoparticles can enable recognition, imaging, and delivery of treatments to cancer cells. Compared to methods based on antibodies and other large biomolecules, inhibitor-mediated targeting benefits from the low molecular weight of the inhibitor molecules, which are typically stable, easy-to-handle, and able to bind the enzyme with very high affinity. Although GCPII is established as a molecular target, comparing previously reported results is difficult due to the different methodological approaches used. In this work, we investigate the robustness and limitations of GCPII targeting with a diverse range of inhibitor-bearing nanoparticles (various structures, sizes, bionanointerfaces, conjugation chemistry, and surface densities of attached inhibitors). Polymer-coated nanodiamonds, virus-like particles based on bacteriophage Qβ and mouse polyomavirus, and polymeric poly­(HPMA) nanoparticles with inhibitors attached by different means were synthesized and characterized. We evaluated their ability to bind GCPII and interact with cancer cells using surface plasmon resonance, inhibition assay, flow cytometry, and confocal microscopy. Regardless of the diversity of the investigated nanosystems, they all strongly interact with GCPII (most with low picomolar <i>K</i>_i values) and effectively target GCPII-expressing cells. The robustness of this approach was limited only by the quality of the nanoparticle bionanointerface, which must be properly designed by adding a sufficient density of hydrophilic protective polymers. We conclude that the targeting of cancer cells overexpressing GCPII is a viable approach transferable to a broad diversity of nanosystems