Nano-bio interactions between carbon nanomaterials and blood plasma proteins: why oxygen functionality matters

Carbon nanomaterials are some of the most versatile nanomaterials. Along with increasing explorations into their utilization in a plethora of biological and biomedical applications, there have been emerging interests and needs in understanding the molecular hemocompatibility of these engineered nanomaterials when coming into contact with blood. Here, we evaluate the nano-bio interactions of one-dimensional (1D) and two-dimensional (2D) carbon nanomaterials with blood plasma proteins. Different facets of the nanomaterial–protein interactions, specifically, the adsorption, equilibrium binding and conformational stability of proteins upon association with carbon nanomaterials are established, based on the quantification of various parameters, such as association constant, binding cooperativity and protein secondary structural change. In light of our data, we demonstrate that the carbon nanomaterial–plasma protein interactions may be significantly influenced by the density of the oxygenated functionalities of the nanomaterials and to a certain extent, their dimensionality and surface area. This work offers a broad insight into the nano-bio interactions between carbon nanomaterials and blood plasma proteins and provides a strong basis for the design and use of 1D and 2D carbon nanomaterials for a wide variety of bioapplications. Oxygenated functional groups on one- and two-dimensional carbon nanomaterials play important roles in determining their interactions with blood plasma proteins. Chwee Teck Lim from the National University of Singapore and colleagues investigated how albumin, globulin and fibrinogen proteins found in blood plasma formed complexes with three types of tiny carbon compounds — short nanotubes containing carboxyl groups, thin graphene nanoplatelets and Swiss cheese—like sheets of porous graphene oxide. Using ultraviolet-visible and fluorescence spectroscopy techniques to probe biomolecular loading, the team found that porous graphene oxide had a greater affinity for proteins than nanotubes or nanoplatelets, in correlation with the density of oxygenated groups on each structure. Polarized-light measurement indicated that at a concentration of 40 micrograms per milliliter, porous graphene oxide induced conformational changes to fibrinogen that include a possible helix unraveling and protein denaturing. The nano-bio interactions of 1D and 2D carbon nanomaterials (COOH-functionalized carbon nanotube (CNT-COOH), graphene nanoplatelet (GNP) and porous graphene oxide (PGO)) with blood plasma proteins (albumin, globulin and fibrinogen) are evaluated in this work. It is demonstrated that these associations may be significantly influenced by the density of the oxygenated functionalities of the nanomaterials and to a certain extent, their dimensionality and surface area. This work offers a broad insight into the carbon nanomaterial–plasma protein interactions and provides a strong basis for the design and use of low-dimensional carbon nanomaterials for a wide variety of biological and biomedical applications.