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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.

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Biochemical and biological properties of glycoconjugates are strongly determined by the specifi c structure of its glycan parts. Glycosylation, the covalent attachment of sugars to proteins and lipids, is very complex and highly-coordinated process involving > 250 gene products. Defi ciency of glycosylation enzymes or transporters results in impaired glycosylation, and consequently pathological modulation of many physiological processes. Inborn defects of glycosylation enzymes, caused by the specifi c mutations, lead to the development of rare, but severe diseases -congenital disorders of glycosylation (CDGs). Up today, there are more than 45 known CDGs. Their clinical manifestations range from very mild to extremely severe (even lethal) and unfortunately, only three of them can be eff ectively treated nowadays. CDG symptoms highly vary, though some are common for several CDG types but also for other unrelated diseases, especially neurological ones, leaving the possibility that many CDGs cases are under-or misdiagnosed. Glycan analysis of serum transferrin (by isoelectric focusing or more sophisticated methods, such as HPLC (high-performance liquid chromatography) or MALDI (matrix-assisted laser desorption/ionization)) or serum N-glycans (by MS), enzyme activity assays and DNA sequence analysis are the most frequently used methods for CDG screening and identifi cation, since no specifi c tests are available yet. In this review we summarize the current knowledge on the clinical, biochemical and genetic characteristic of distinct CDGs, as well as existing diagnostic and therapeutic procedures, aiming to contribute to the awareness on the existence of these rare diseases and encourage the eff orts to elucidate its genetic background, improve diagnostics and develop new strategies for their treatment.