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Physical forms of microparticles and nanoparticles, such as the size, charge, and shape, are known to affect endocytosis. Improving the physical designs of the drug carriers can increase the drug uptake efficiency and the subsequent drug efficacy. Simple shapes, such as sphere and cylinder, have been studied for their ability for endocytosis. To have a better understanding of the shape effect on cellular uptake, different particle shapes were prepared, using the keyboard character shapes, and their impacts on cellular uptake were examined. The results showed that shapes with higher aspect ratios and sharper angular features have a higher chance of adhering to the cells and become internalized by the cancer cells. The local interaction between the cell membrane and the part of the microparticle in contact with the cell membrane also plays a crucial role in determining the outcome.

Retinal trauma is a serious concern for patients undergoing inner limiting membrane (ILM) peeling to correct for various vitreoretinal interface conditions. This mechanical trauma can be prevented by modifying the surface of surgical instruments to increase adhesion to the ILM. To this effect, we have studied the effects of roughness and surface charge on the adhesive properties of ILMs by utilizing layer-by-layer (LbL) films with embedded gold nanoparticles (LbL-AuNP films). LbL films were assembled on atomic force microscopy (AFM) tipless cantilevers. Topographical analysis of these films, with and without nanoparticles, showed that LbL films with nanoparticles had a higher rms roughness compared to films alone or unmodified cantilevers. Nanoparticle-modified LbL films significantly increased the adhesion forces at the cantilever–ILM interface, compared to LbL films without particles. Surprisingly, adsorption of gold nanoparticles onto the AFM cantilevers caused increases in adhesion forces greater than those measured with LbL-AuNP films. These results have important implications for the design of surface modifications for vitreoretinal surgical instruments.