Highly sensitive resonance light scattering bioassay for heparin based on polyethyleneimine-capped Ag nanoclusters

Ag nanoclusters (NCs) possessed distinct physical and chemical attributes that made them excellent scaffolds for the development of novel bio-analytical methodology. In the present work, a green approach for the preparation of Ag nanoclusters (NCs) was proposed on the basis of templated polyethyleneimine (PEI) assisted in-situ reductive crystallization of Ag (I), and then a sensitive resonance light scattering bioassay for the determination of heparin was established on the basis of the enhanced resonance light scattering of the PEI-capped Ag NCs during the presence of heparin. Further investigation indicated that the molecular weight of PEI, the PEI/Ag (I) ratio and the pH value of reaction conditions had great influence on the formation of Ag NCs, which was directly correlated to resonance light scattering. The bioassay allows sensitive and selective detection of heparin with a detection limit of 27.5   nM, and successfully applied for the determination of heparin in human serum samples.