Graphene: a versatile nanoplatform for biomedical applications

Nanographene oxide-based radioimmunoconstructs for in vivo targeting and SPECT imaging of HER2-positive tumors

Nanographene oxide (NGO) is a novel nano-wall material that tracks to tumors in vivo, and which, as a consequence of its large surface area, has the capacity to carry a large payload. This study explores the use of anti-HER2 antibody (trastuzumab)-conjugated NGO, radiolabeled with (111)In-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) via ππ-stacking, for functional imaging. In two HER2-overexpressing murine models of human breast cancer, high tumor-to-muscle ratio was achieved, resulting in clear visualization of tumor using single-photon emission computed tomography (SPECT). In the BALB/neuT model and in BALB/c nu/nu mice bearing 231/H2N xenografts, tumor accumulation amounted to 12.7 ± 0.67 and 15.0 ± 3.7% of the injected dose/g (%ID/g) of tumor tissue at 72 h, with tumor-to-muscle ratios of 35:1 and 7:1, respectively. Radiolabeled NGO-trastuzumab conjugates demonstrated superior pharmacokinetics compared to radiolabeled trastuzumab without NGO, with more rapid clearance from the circulation. The use of NGO as a scaffold to build radiolabeled nano-immunoconstructs holds promise for molecular imaging of tumors.

Hydrogen bonding-driven rheological modulation of chemically reduced graphene oxide/poly(vinyl alcohol) suspensions and its application in electrospinning

Rheology of graphene oxide (GO) and chemically reduced graphene oxide (RGO) nanosheets suspended in poly(vinyl alcohol) (PVA) solution were investigated by altering nanosheet loading and reduction time of RGO in a wide range. A small amount (0.5 wt%) of GO and RGO in the dilute regime of filler resulted in a threefold increase and a fourfold decrease in steady viscosity at 0.01 s(-1), respectively; increasing GO and RGO loadings in the semi-dilute regime of filler caused steady viscosity to increase to different degrees. Meanwhile, the steady viscosity of the suspension decreased gradually by more than one order of magnitude with increasing reduction time of RGO. By characterizing the microstructure in suspensions, the style and relative density of H-bonding between PVA chains and nanosheets were confirmed to account for the suspension rheology. Modulation of viscosity in a wide range via simply control of the loading and reduction time of RGO was hydrogen bonding-driven, which was successfully applied to electrospinning to prepare nanocomposite nanofibers. The addition of 1 wt% GO and RGO with respect to the polymer mass significantly improved PVA fibrous uniformity and fineness, and the spinnable concentration range of PVA was greatly broadened from (8.5-11.3 wt%) to (5-18 wt%). Meanwhile, the thermal stability of the nanofibers was also enhanced by GO or RGO addition.