Optimization of Bio-Nano Interface Using Gold Nanostructures as a Model Nanoparticle System

Better knowledge of interface between nanotechnology and biology will lead to advanced biomedical tools for imaging and therapeutics. In this review, recent progress in the understanding of how size, shape, and surface properties of nanoparticles (NPs) affect intracellular uptake, transport, and processing of NPs will be discussed. Gold NPs are used as a model system in this regard since their size, shape, and surface properties can be easily manipulated. Recent experimental and theoretical studies have shown that NP-uptake is dependent upon size and shape of the NPs. Within the size range of 2-100 nm, Gold nanoparticles (GNPs) of diameter 50 nm demonstrate the highest uptake. Cellular uptake studies of rod-shaped gold nanoparticles (GNRs) show that there is a decrease in uptake as the aspect ratio of GNRs increases. The surface ligand and charge of NPs play an important role in their uptake process as well. Different proteins on the surface of the NPs can be coated for effective targeting of NPs into specific organelles. Once in the cell, most of the NPs are trafficked via an endo-lysosomal path followed by a receptor mediated endocytosis process at the cell membrane. Exocytosis of NPs is also dependent on the size and shape of the NPs, however, the trend was different to endocytosis process. These findings provide useful information to tailor nano-scale devices at single cell level for effective applications in diagnosis, therapeutics, and imaging.