Biological Recognition of Graphene Nanoflakes

Graphene has recently attracted tremendous interest in several biomedical fields such as drug delivery, cancer therapies and biosensing. Opportunities in this emerging field therefore will require the systematic study of the... [ view full abstract ]

Graphene has recently attracted tremendous interest in several biomedical fields such as drug delivery, cancer therapies and biosensing. Opportunities in this emerging field therefore will require the systematic study of the biological interactions of graphene when exposed to biofluids and cells. We now recognize that the early stages of biological impacts, governed for example by receptor interactions, require surface presentations that are representative of real exposure conditions in blood.

In this work we developed a facile, biocompatible long-term colloidally stable water dispersion of few-layered graphene nanoflakes directly in the biological media of interest, by mean of ultrasound assisted liquid exfoliation.¹ We applied recently developed immunoprobing protocols^{2, 3} in order to assess the functionality and availability of specific epitopes of interest situated on the periphery of the graphene nanoflakes biological surface (Figure 1). These key motifs are likely to mediate most of the early biological interactions. Finally, by mean of cell transfection protocols, we studied the interactions between graphene nanoflakes and specific overexpressed cell receptors able to engage with the key motifs identified on the surface.⁴

The evidence accumulated from experiments and controls suggests that, in sharp contrast to many other nanomaterials, graphene flakes present a negligible proportion of apolipoprotein B100 type recognition motifs, but are rich in effective apolipoprotein A-I presentation. This is confirmed by the receptor driven uptake that resulted much higher when SRB1 receptors (able to recognise apolipoprotein A-I) were overexpressed on the surface of the cell (Figure 2).

The basis set here using graphene and serum proteins opens the way for detailed and mechanistic biological studies based on meaningful biomolecular surface presentations.

1. A. Ciesielski, P. Samorì, Chemical Society Reviews, 2014, 43, 381-398.

2. P. M. Kelly et al., Nature nanotechnology, 2015, 10, 472-479.

3. M. C. Lo Giudice et al., Nature Communications, 2016, 7, 13475.

4. S. Lara et al., ACS nano, 2017, 11.2, 1884-1893.