Gold and silver nanoparticles based superquenching of fluorescence: A review

The short review highlights the recent advances on the gold and silver nanoparticles induced efficient quenching of fluorescence from various fluorophores looking at their promising use as optical rulers and chemo-/bio-sensors. The fluorescence quenching often leads to the increase in the Stern-Volmer constant (Ksv similar to 10(7)-10(10) mol(-1) dm(3)) several orders of magnitude higher than the values observed for the normal photochemical quenching processes (similar to 10(2) mol(-1) dm(3)). This amplified quenching has been termed as super-quenching or hyper-quenching. Energy transfer (ET) is established from the donor to the metal nanoparticles rationalizing these fast quenching processes. Considering the distance dependence of the ET process, Forster resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) are ascribed to take place. These sensitive distance dependent phenomena serve as the spectroscopic ruler to measure the intra-or intermolecular distances between the interacting partners. In this account focus has been laid on the size dependent energy transfer and super-and hyper-quenching of the fluorescence of the donor moieties by the nanometals and their probable applications in sensing. Rationalization has been made for the nanoparticle induced huge enhancement in the quenching efficiency. The impact of this review lies in the possible application of these amplified quenching processes in designing high sensitive chemical and biological sensors. (C) 2014 Elsevier B.V. All rights reserved.