Using the Ring-Shaped Protein TRAP to Capture and Confine Gold Nanodots on a Surface

The cavity of the toroidal protein TRAP (trp RNA‐binding attenuation protein) is modified to capture gold nanodots in solution. By engineering a titanium‐binding peptide onto one surface of the ring it is also possible to bind it specifically and tightly to a TiO2 surface. TRAP bound in this way is then used to capture gold nanodots and attach them to prepared surfaces. Gold‐protein complexes are observed using atomic force microscopy and transmission electron microscopy. The modified TRAP is used to build gold nanodots into the SiO2 layer of a metal oxide semiconductor. This is the first use of a ring protein, rather than the more commonly used spherical protein cages, to constrain nanodots to a surface. This method is an important addition to the current range of bionanotechnology tools and may be the basis for future, multicomponent electronic devices. The toroidal protein TRAP (trp RNA‐binding attenuation protein, see image) is modified to capture gold nanodots in solution. A titanium‐binding peptide attached to one surface of the ring makes it possible to bind it specifically and tightly to a TiO2 surface. TRAP bound in this way is then used to capture gold nanodots and attach them to prepared surfaces. A prototype metal oxide semiconductor capacitor can be made using such gold‐nanodot‐bound TRAP surfaces.