Abstract
Sheet‐shaped carriers, having both obverse and reverse surfaces and thus a large contact area for targeting a site, have several advantages over spherical‐shaped carriers, which have an extremely small contact area for targeting sites. Here, we proposed a novel method to prepare a free‐standing ultrathin and biocompatible nanosheet having heterosurfaces, by a combination of four processes: (1) specific adsorption of recombinant human serum albumin (rHSA) molecules onto a patterned octadecyltrimethoxysilane self‐assembled monolayer region (ODS‐SAM), (2) preparation of nanosheets of rHSA molecules bearing thiol groups (SH‐rHSA) via two‐dimensionally disulfide crosslinking, (3) surface modification of the resulting nanosheet, and (4) preparation of the free‐standing nanosheet by detachment from the ODS‐SAM. The SH‐rHSA molecules at pH 5.0 and a concentration of 1 μg/mL were specifically adsorbed on the patterned ODS‐SAM regions by hydrophobic interaction, and were two‐dimensionally crosslinked in the presence of copper ion as an oxidant. The rHSA‐nanosheets were then simply detached from the ODS‐SAM by treatment with surfactant. We succeeded in the preparation of rectangular (10 μm × 30 μm) and ultrathin (4.5 ± 1.0 nm) rHSA‐nanosheets on a patterned ODS‐SAM, and could also obtain free‐standing rHSA‐nanosheets having heterosurfaces by surface modification with fluorescent latex beads. Thus, the rHSA‐nanosheets having heterosurfaces could be regarded as a new biomaterial for drug carriers, hemostatic reagents, wound dressing for burn injury, and so forth. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009