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Emergence of Selectivity in Inherently Nonselective Gold Nanoparticles Through Preferential Breaking of Interparticle Interactions

submitted on 11.10.2018, 16:39 and posted on 15.10.2018, 16:54 by Anish Rao, Govind Sasi Kumar, Soumendu Roy, Ajesh T. R., Gayathri Devatha, Pramod Pillai

We demonstrate a fundamentally unique identification strategy to impart selectivity to a traditionally and inherently nonselective carboxylate-functionalized gold-nanoparticles ([-] AuNPs), without the aid of any analyte specific ligands. The common practice is to use the ability of divalent ions to trigger the aggregation process in a kinetically trapped dispersed solution of [-] AuNPs. Aggregation of NPs being a thermodynamically favourable process will result in a uniform and nonselective turn-off response from most of the strongly binding divalent ions. Our approach is to use the abilities of various divalent ions to break a thermodynamically stable inter-nanoparticle precipitates containing [+] and [-] AuNPs (nanoionic precipitates), as the means of identification. Importantly both [+] and [-] AuNPs, independently, were ‘blind’ in terms of selectivity towards divalent ions. Remarkably, a hybrid-system composed of such nonselective nanoparticles was able to discriminate between the hard-to-distinguish pair of Pb2+ and Cd2+ ions. The rationale is that only the strongest of strongly binding ions will be able to break the interactions between the NP precipitates (thermodynamically stable state) and re-disperse them back in solution (kinetically trapped state). This is in stark contrast with the conventional idea of forming an interaction between NPs and divalent ions, with the help of analyte-specific ligands.


DST-SERB Grant No. EMR/2015/001561 and DST Nanomission Thematic Unit Program, India.


Email Address of Submitting Author


Indian Institute of Science Education and Research Pune



ORCID For Submitting Author


Declaration of Conflict of Interest

There are no conflicts to declare.