Fabrication, Properties, and Biomedical Applications of Nanosheets

Nanosheets, ultrathin sheet-shaped materials, have several advantages in the biomedical field; a large contact area in the biointerface, noncovalent adhesion, small amount ofmaterial required, and dual surfaces for heterofunctionalization. In terms of a drug-delivery vehicle, the sheet-shaped carriers perform unique dynamic functions over spherically shaped carriers. For surgical dressing, the sheet-shaped materials can densely overlap the tissue defect site without the need for chemical adhesive reagents. In this review, we propose a methodology for the preparation of freestanding, ultrathin nanosheets with a huge aspect ratio and heterosurfaces, fabricated through molecular assembly. In their practical biomedical applications, the micrometer-sized nanosheet was constructed by exploiting a micropatterned substrate with a precisely controlled size, applicable for injectable sheet-shaped drug carriers, whereas the giant nanosheets, with an aspect ratio of >106, can act as novel biomaterials for surgical dressing in the next generation of minimally invasive treatments.