In Situ Growth of Chiral Gold Nanoparticles in Confined Silica Nanotube

We reported here that chiral gold nanoparticles can be in situ created inside a confined chiral silica nanotube. A bolaamphiphilic L-glutamic acid was found to self-assemble into nanotube and transcribed its chirality into the silica through co-assembly with ATPS and TEOS. After removing the bolaamphiphile, "chiral" alignment of propylamine groups or "chiral imprint" remained inside the silica nanotube. NaAuCl4 was absorbed into silica nanotube via electrostatic and coordination interaction with propylamine groups. After in situ reducing with ascorbic acid, the gold nanoparticles were formed inside the nanotube, which exhibited chiral optical activity. Interestingly, the chirality of gold nanoparticles still remained even after removing the silica nanotube template with HF, proved that the "chiral imprint" is strongly "memorized" by the gold nanoparticles.