Interaction of differently sized, shaped, and functionalized silver and gold nanoparticles with glycosylated versus nonglycosylated transferrin

Exposure of nanomaterials (NMs) to biological medium results in their direct interaction with biomolecules and the formation of a dynamic biomolecular layer known as the biomolecular corona. Despite numerous published data on nano-biointeractions, the role of protein glycosylation in the formation, characteristics, and fate of such nano-biocomplexes has been almost completely neglected, although most serum proteins are glycosylated. This study aimed to systematically investigate the differences in interaction of metallic NPs with glycosylated vs nonglycosylated transferrin. To reach this aim, we compared interaction mechanisms between differently sized, shaped, and surface-functionalized silver NMs and gold NMs to commercially available human transferrin (TRF), a glycosylated protein, and to its nonglycosylated recombinant form (ngTRF). Bovine serum albumin (BSA) was also included in the study for comparative purposes. Characterization of NMs was performed using transmission electron microscopy and dynamic and electrophoretic light scattering techniques. Fluorescence quenching and circular dichroism methods were used to evaluate protein binding constants on the nanosurface and conformational changes after the protein–NM interactions, respectively. Competitive binding of TRF, ngTRF, and BSA to the surface of different NMs was evaluated by separating them after extraction from protein corona by gel electrophoresis following quantification with a commercial protein assay. The results showed that the binding strength between NMs and transferrin and the changes in the secondary protein structure largely depend not only on NM physicochemical properties but also on the protein glycosylation status. Data gained by this study highlight the relevance of protein glycosylation for all future design, development, and efficacy and safety assessment of NMs.
This study is based upon collaborative work from COST Action CA 17140 “Cancer Nanomedicine from the Bench to the Bedside” supported by COST (European Cooperation in Science and Technology). It was financially supported by the “Research Cooperability” Program of the Croatian Science Foundation funded by the European Union from the European Social Fund under the Operational Programme Efficient Human Resources 2014–2020 (grant HRZZ-PZS-2019-02-4323), Ministerio de Ciencia e Innovacion (Spain, grant BIO2017–84246-C2–1-R), Fondo Social de la DGA (grupos DGA), and Croatian Science Foundation (grant number HRZZ-IP-2016-06-2436). The authors would like to acknowledge the use of the Advanced Microscopy Laboratory (INMA-Universidad de Zaragoza) for access to their instrumentation and expertise.