Synthesis of green-emitting Pt_8 nanoclusters for biomedical imaging by pre-equilibrated Pt/PAMAM (G4-OH) and mild reduction

We synthesized green-emitting platinum (Pt) nanoclusters (excitation: 460 nm, emission: 520 nm) by reducing Pt ions from pre-equilibrated Pt/fourth-generation poly(amidoamine) dendrimers (PAMAM (G4-OH)) complexes with a mild reductant. The structural characteristics of the resulting Pt nanoclusters, Pt8L8 (L = C2H2O2S), were determined by Electrospray ionization (ESI) mass spectroscopy. These nanoclusters possess a 28% quantum yield, which is higher than those of green-emitting Au and Ag nanoclusters. We also found that Pt nanoclusters have considerably low cytotoxicity and biocompatibility, and demonstrated that they could be used for biomedical imaging. This study provides the possibility to extend the photoluminescent wavelength of Pt nanoclusters to the near infrared region, which is ideal for biological imaging applications.