The complexation of Pt2＋ ions with G5.5-COOCH3 PAMAM dendrimers was investigated by UV-VIS and FT-IR spectral methods, showing that Pt2＋ ions are coordinated with the interior amino groups of dendrimers. It needs more time for the complexation reaction to come to balance with the increase of molar ratios of Pt2＋ ions to dendrimers. The maximum loadings of 50～55 Pt2＋ ions within the G5.5- COOCH3 dendrimers were also obtained. Following reduction with NaBH4 resulted in spherical and well-dispersed Pt nanoparticles (average size＜2 nm) encapsulated in the dendrimers as shown in HRTEM images. When the ratio of Pt2＋ ions to dendrimers was 10, the yielded Pt nanoparticles with smaller sizes and a narrow distribution were intradendrimer templated. When the ratio of Pt2＋ ions to dendrimers was 50, new partially formed Pt nanoparticles with larger sizes and a broad distribution were intradendrimer templated.

Key words: poly(amidoamine) (PAMAM) dendrimer, template, Pt nanoparticle