From Bench to Cell: A Roadmap for Assessing the Bioorthogonal 'Click' Reactivity of Magnetic Nanoparticles for Cell Surface Engineering

In this work, we report the use of bioorthogonal chemistry, specifically the strain-promoted click azide–alkyne cycloaddition (SPAAC) for the covalent attachment of magnetic nanoparticles (MNPs) on living cell membranes. Four types of MNPs were prepared, functionalized with two different stabilizing/passivation agents (a polyethylene glycol derivative and a glucopyranoside derivative, respectively) and two types of strained alkynes with different reactivities: a cyclooctyne (CO) derivative and a dibenzocyclooctyne (DBCO) derivative. The MNPs were extensively characterized in terms of physicochemical characteristics, colloidal stability, and click reactivity in suspension. Then, the reactivity of the MNPs toward azide-modified surfaces was evaluated as a closer approach to their final application in a living cell scenario. Finally, the DBCO-modified MNPs, showing superior reactivity in suspension and on surfaces, were selected for cell membrane immobilization via the SPAAC reaction on the membranes of cells engineered to express azide artificial reporters. Overall, our work provides useful insights into the appropriate surface engineering of nanoparticles to ensure a high performance in terms of bioorthogonal reactivity for biological applications.
This work has been supported by the European Commission, MagicCellGene Project (M-ERA.NET COFUND call 2016, funded by Ministerio de Economía y Competitividad, MINECO, Spain in the framework of the PCIN-2017-060 project), Ministerio de Innovación, Ciencia y Universidades (MCIU, PGC2018-096016-B-I00 to R.M.F), Ministerio de Economía, Industria y Competitividad (BIO 2017-84246-C2-1R to V.G. and J.M.F.), and MINECO and FSE/Agencia Estatal de Investigación (Ramón y Cajal subprogram, grant RYC-2015-17640 to R.M.F.). J.I.L. and E.M.A acknowledge financial support for their predoctoral fellowships from Gobierno de Aragón (DGA 2017–2021 call, co-funded by the Programa Operativo Fondo Social Europeo de Aragón 2014–2020) and Ministerio de Universidades (FPU17/02024), respectively. Authors also acknowledge support from Gobierno de Aragón and Fondos Feder for funding the Bionanosurf (E15_20R) research group. J.M.A. and M.E. acknowledge support from the Basque Government (GIC-2015_IT-1033-16).